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Godina (Volume) 15, Broj (Number) 4, Oktobar - Decembar (October - December) 2018.

ISSN 1512-5173 (Print)ISSN (On-line2637-1510

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187

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MAŠINSTVO ČASOPIS ZA MAŠINSKO INŽENJERSTVO

JOURNAL OF MECHANICAL ENGINEERING Godina (Volume) 15, Broj (Number) 4, Zenica, Oktobar – Decembar (October – December) 2018.

Uredništvo (Editorial): Fakultetska 1, 72000 Zenica Bosnia and Herzegovina Tel: +387 32 449 143; 449 145 Fax: +387 32 246 612 e-mail: [email protected] [email protected] [email protected]

Osnivač i izvršni izdavač (Founders and Executive Publisher): University of Zenica Faculty of Mechanical Engineering Fakultetska 1, 72000 Zenica Bosnia and Herzegovina Recenzioni odbor (Review committe): Dr. Aleksandar Karač, Dr. Nedim Hodžić, Dr. Nagib Neimarlija, Dr. Samir Lemeš, Dr. Nermina Zaimović-Uzunović

Glavni i odgovorni urednik (Editor and Chief): Prof. Dr. Sc. Safet Brdarević

Časopis izlazi tromjesečno (The journal is published quarterly)

Urednički odbor (Editorial Board): Dr. Safet Brdarević (B&H), Dr. Jože Duhovnik (Slovenia), Dr. Vidosav Majstorović (Serbia), Dr. Milan Jurković (Croatia), Dr. Sabahudin Ekinović (B&H), Dr. Gheorge I. Gheorge (Romania), Dr. Alojz Ivanković (Ireland), Dr. Joan Vivancos (Spain), Dr. Ivo Čala (Croatia), Dr. Slavko Arsovski (Serbia), Dr. Albert Weckenman (Germany), Dr. Ibrahim Pašić (France), Dr. Zdravko Krivokapić (Montenegro), Dr. Rainer Lotzien (Germany)

Lektori: Azra Adžemović, profesor Dr. Nebojša Vasić Tehnički urednik (Technical Editor): Prof. Dr. Sabahudin Jašarević Štampa (Print): Štamparija Fojnica d.o.o., Fojnica Uređenje zaključeno (Preparation ended): 31.12.2018.

Časopis je evidentiran u evidenciji javnih glasila pri Ministarstvu nauke, obrazovanja, kulture i sport Federacije Bosne i Hercegovine pod brojem 651. Časopis u pretežnom iznosu finansira osnivač i izdavač. Časopis MAŠINSTVO u pravilu izlazi u četiri broja godišnje. Rukopisi se ne vraćaju

The Journal is listed under No 651 in the list of public journals in the Ministry of science, education, culture and sport of the Federation of Bosnia and Herzegovina. The Journals is mostly financed by founder and publisher. Frequency of Journal MAŠINSTVO is 4 issues a year. Manuscripts are not returned

Časopis objavljuje naučne i stručne radove i informacije od interesa za stručnu i privrednu javnost iz oblasti mašinstva i srodnih grana vezanih za područje primjene i izučavanja mašinstva. Posebno se obrađuju slijedeće tematike: - tehnologija prerade metala, plastike i gume, - projektovanje i konstruisanje mašina i postrojenja, - projektovanje proizvodnih sistema, - energija, - održavanje sredstava za rad, - kvalitet, efikasnost sistema i upravljanje proizvodnim i poslovnim sistemima, - informacije o novim knjigama, - informacije o naučnim skupovima - informacije sa Univerziteta,

The journal publishes scientific and professional papers and information of interest to professional and economic releases in mechanical engineering and related fields. In particular, the following topics are treated: - Technology for processing metal, plastic and rubber, - Design and construction of machines and plants, - The design of production systems, - Energy, - Maintenance funds for the work, - Quality and efficiency of the system and the management of production and business systems, - Information about new books, - Information about scientific meetings - Information from the University,

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RIJEČ UREDNIKA Poštovane kolegice i kolege Pred sobom imate jubilarni, 60 – ti broj Vašeg časopisa koji se pojavio prije 22 godine, 1996. godine, i poslije prekida od sedam godina nastavio izlaženje kao jedini časopis iz oblasti mašinstva u Bosni i Hercegovini. U ovih 15 godina izlaženja objavljeno je 326 radova od 876 autora i koautora iz 14 zemalja Evrope. Tu su 28 kratkih prikaza istraživačkih kapaciteta BiH (prva strana korica) i 56 prikaza proizvodnih kapaciteta iz metalskog kompleksa BiH (zadnja strana korica). U sadržaju su date i 126 informacija o naučno – stručnim konferencijama, seminarima, našim knjigama i manifestacijama značajnim za područje mašinstva. To je rezultat rada brojnih učesnika autora, koautora, recenzenata, redakcije i naravno sponzora. Svima se zahvaljujemo i očekujemo uspješan nastavak našeg zajedničkog rada na našu korist, korist struke i nauke, Bosne i Hercegovine i svijeta. Od Decembra ove ove godine Časopis „MAŠINSTVO“ se nalazi u bazi Index Copernicus sa ICV 77,85.

Vaš glavni i odgovorni urednikProf. emeritus dr. Safet Brdarević

EDITORIAL Dear Colleagues In front of you you have a jubilee, 60th issue of your magazine that appeared 22 years ago in 1996, and after seven years of interruption, continued to be the only magazine in the field of machinery in Bosnia and Herzegovina. In these 15 years of publication, 326 papers were published by 876 authors and co-authors from 14 countries in Europe. There are 28 short explorations of BiH's exploration capacity (first part of the crate) and 56 production capacity representations from the BiH metal complex (the back of the crate). The contents include 126 information on scientific and professional conferences, seminars, our books and events relevant to the field of machinery. This is the result of the work of numerous authors, co-authors, reviewers, editors and of course sponsors. We are grateful for all and are looking forward to a successful continuation of our joint work for our benefit, the benefit of the profession and the science of Bosnia and Herzegovina and the world. Since December this year, the magazine "MAŠINSTVO" is based in Index Copernicus with ICV 77.85. Your editor in chief Prof. emeritus dr. Safet Brdarević

SADRŽAJ

1. Kombinovana eksperimentalno-numerička analiza elastičnih lopti izloženih na pritisak između ploča Kargić, M.: Karač A. 189 2. Utvrđivanje intervala rekalibracije laboratorijske opreme Kubat, A.; Pašalić, S.; Bečirović, A.; Lemeš, S.; Obučina, M. 199

3. Primjer kranioplastike uz asistenciju tehnologije 3D printanja: Prikaz slučaja Spahić, D.; Bečulić, H. 207

4. Uticaj oblika konvergentne mlaznice na kvalitet strujanja u testnoj sekciji zračnog tunela Bešlagić, E. 213 5. Mogućnost korištenja tekstilnog otpada kao energenta u cementnoj industriji Šišić, M. 227 6. Izrada modela aditivnim postupkom 3D printanja i dimenzionalna provjera na CMM Zaimović-Uzunović, N.; Kačmarčik, J.; Vardaa, K.; Lemeš, S.; Spahić, D. 237

7. Recycling of Ferrous by-Products in Iron and Steel Plants Schwelberger, J.; Brunner, Fleischanderl, A.; Mandara, Z. 245 Informacije 252 Uputstvo za autore 254

CONTENTS

1. Combined Experimental-Numerical Analysis of Elastic Balls Subjected to Compression Between Plates Kargić, M.: Karač A. 189 2. Determining Recalibration Interval for Laboratory Equipment Kubat, A.; Pašalić, S.; Bečirović, A.; Lemeš, S.; Obučina, M. 199

3. An Example of Cranioplasty with the Assistance of 3D Printing Technology: A Case Report Spahić, D.; Bečulić, H. 207

4. Influence of Contraction Shape on the Flow Quality in Wind Tunnel Test Section Bešlagić, E. 213 5. Possibility of Using Textile Waste as an Energy in Cement Industry Šišić, M. 227

6. 3D Printing Additive Procedure Model Creation and Dimensional Check Using CMM Zaimović-Uzunović, N.; Kačmarčik, J.; Vardaa, K.; Lemeš, S.; Spahić, D. 237 7. Recycling of Ferrous by-Products in Iron and Steel Plants Schwelberger, J.; Brunner, Fleischanderl, A.; Mandara, Z. 245 Informations 252 Instruction for authors 254

Mašinstvo 4(15), 189 – 198, (2018) M. Kargić, A. Karač: COMBINED EXPERIMENTAL …

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KOMBINOVANA EKSPERIMENTALNO-NUMERIČKA ANALIZA ELASTIČNIH LOPTI IZLOŽENIH NA PRITISAK IZMEĐU PLOČA

COMBINED EXPERIMENTAL-NUMERICAL ANALYSIS OF ELASTIC

BALLS SUBJECTED TO COMPRESSION BETWEEN PLATES

Muamer Kargić Trendy d.o.o. Novi Travnik Aleksandar Karač Polytechnic Faculty University of Zenica Ključne riječi: elastična lopta, test na pritisak, numeričko rješavanje, MathCAD Keywords: elastic ball, compression test, numerical solution, MathCAD Paper received: 03.10.2018. Paper accepted: 24.11.2018.

Originalni naučni radREZIME U radu je predstavljen kombinovani postupak određivanja mehaničkih osobina elastičnih lopti ispunjenih fluidom pomoću testa na pritisak i odgovarajućeg analitičko-numeričkog rješenja. Korištene su obične dječje lopte, koje su modelirane Mooney-Rivlin modelom materijala. Dobiveni rezultati ovom kombinovanom numeričko-eksperimentalnom analizom upoređeni su s rezultatima testa na zatezanje. Dobivena su odlična slaganja u pogledu mjerenih i simuliranih veličina modula elastičnosti i debljine stijenke lopte.

Original Scientific paper

SUMMARY This work presents the combined method for determination of mechanical characteristics of elastic balls filled with fluid by using compression test and appropriate analytical-numerical method. Ordinary playing balls, being modelled with the Mooney-Rivlin material model, are used in the study. Results obtained by this combined numerical-experimental analysis are compared with tensile test results. Very good agreements are achieved in terms of measured and simulated modulus of elasticity and ball thickness.

1. UVOD Pojam „elastična lopta“ u kontekstu ovog istraživanja predstavlja sferični tankostjeni objekat izrađen od (hiper)elastičnog materijala, koji je ispunjen fluidom. Da bi se odredile karateristike materijala od kojih je izrađena takva lopta, uobičajeno je da se lopta razreže, odnosno uništi, iz nje naprave odgovarajuće epruvete, a zatim te epruvete ispitaju koristeći neku od metoda ispitivanja (na primjer, test na zatezanje). Ovakva standardizirana ispitivanja s razaranjem često puta nisu moguća, jer broj takvih objekata može biti ograničen, objekti mogu biti skupi, ali i vrijeme ispitivanja može da igra ključnu ulogu. Također, objekat koji treba ispitati može biti potreban za dalje korištenje. [1]

1. INTRODUCTION

The term „elastic ball“ in this study is referred to a thin-walled spherical object made of (hyper)elastic material filled with fluid. In order to determine the material characteristics of such balls, it is common to cut the ball, ie. to destroy it, make specimens and test them using a test method (eg. tensile test). These standard destructive tests are not always possible due to limited number of objects, the objects may be expensive, or the time for testing may play a significant role. In addition, the object may be necessary for further use. [1]


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Jedan od načina na koji se indirektno, bez razaranja, može doći do mehaničkih osobina materijala lopte (ali i dimenzionih) je kombinacija eksperimentalne i numeričke analize testa na pritisak. Na osnovu testa na pritisak moguće je dobiti zavisnost sile pritiska i pomjeranja pritisne ploče. S druge strane, pod pretpostavkom da se stijenka lopte može smatrati membranom, test na pritisak lopte između dvije ploče može se opisati pomoću dvije diferencijalne jednačine višeg reda, a ove jednačine se mogu riješiti numeričkim metodama [2-7]. Na taj način se upoređivanjem rezultata eksperimenta i numeričkog rješenja može doći do mehaničkih (i dimenzionih) osobina materijala, koji zadovoljavaju jednakost numeričkog i eksperimetnalnog rješenja u smislu zavisnosti sila-pomjeranje.

One of the indirect non-destructive methods that can be used to obtain mechanical (and dimensional) characteristics of the ball material is combined experimental and numerical analysis of the compression test. Experimental compression test provides relationship between compression force and displacement of the compression plate. On the other hand, assuming the ball wall to be a membrane, the compression test can be described by a set of two higher-order differential equations that can be solved by numerical methods [2-7]. Thus, by comparing results between experiment and numerical solution, one can obtain a set of mechanical (and dimensional) characteristics of materials that satisfies the equality of both analyses in terms of force-displacement curve

2. ANALITIČKO-NUMERIČKO RJEŠENJE

Analitički model, koji su razvili Feng i Yang [2, 3], bio je uvertira za detaljnija ispitivanja sfernih objekata opterećenih na pritisak [4-7], a problem je u ovom radu riješen pomoću MathCAD aplikacije [8]. Problem se svodi na analizu slučaja kontakta sferične membrane pod pritiskom i krute pritisne ploče, kao što je prikazano na slici 1. .

2. ANALITICAL-NUMERICAL SOLUTION

Analytical model, developed by Feng and Yang [2-3], was an overture to more detailed analyses of spherical objects under compression [4-7]. In this study, the problem is solved using a MathCAD application [8]. The problem description is given in Figure 1, where a pressurised spherical membrane is compressed with a rigid plate.

Slika 1. Geometrija problema pritiska sferične membrane između dvije ploče [2]

Figure 1. Compression of the spherical membrane between plates – problem geometry [2]

Mogu se razlikovati dvije regije: kontaktna i beskontaktna, koje se mogu opisati sistemom od 5 kuplovanih diferencijalnih jednačina prvog reda s početnim uslovima [2,3]. Tako, za beskontaktnu regiju važi sljedeći sistem:

Two regions can be distinguished, contact and non-contact, that can be described by a set of five coupled first-order initial-value differential equations [2,3]. So, for the noncontact region there is a following set of equations:

/After deformation

/Before deformation/inflation

Top view

Side view


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= cos −sin ( , )( , ) − sin ( , )( , ) = ili ′ = − cossin

= + − − −

(1)

(2)

(3)

gdje su λ1 i λ2, glavna izduženja u meridijalnom i obodnom pravcu, respektivno, ψ promjenljiva varijabla (ugao, v. Sliku 1.), δ= λ2sinψ , T1 i T2 glavni rezultantni naponi, p=P/C1, P pritisak unutar membrane (relativni u odnosu na spoljašnji pritisak), C1 karaktersitika materijala (v. dole), f1, f2, f3 su funkcije koje zavise od modela materijala membrane, odnosno glavnih rezultatnih napona:

where λ1 i λ2 are the principal stretches in meridian and circumferential directions, respectively, ψ is variable (angle, see Figure 1), δ= λ2sinψ , T1 i T1 principal stress resultants, p=P/C1, P is internal pressure (relative to the outer pressure), C1 is material parameter (see below), f1, f2, f3 are functions dependent on material model, ie. the principal stress resultants:

, = , , = , ( , ) = − ) (4)

Za kontaktnu regiju sistem jednačina (1)-(3) se reducira na dvije jednačine:

In the case of the contact region the system of Eqs.(1)-(3) reduces to the following two equations: ′ = − sin ( , )( , ) − − cossin ( , )( , ) ′ = − cossin

(5)

(6)

Za kompletiranje sistema je neophodno odabrati model materijala i vrstu fluida, odnosno odgovarajući termodinamički zakon. U ovom radu korišten je dvo-parametarski Moonye-Rivlin model materijala, za koji su glavni rezultanti naponi:

To solve the system it is necessary to chose the material model and type of fluid, ie. thermodynamic law. Here, the two-parameter Mooney-Rivlin model is used for the ball material with the following principal stress resultants:

= 2ℎ − 1 (1 + ) = 2ℎ − 1 (1 + ) (7)

(8)

gdje je h debljina membrane, C1=E/[6(1+α)], E modul elastičnosti, α=C2/C1, C2 drugi parametar materijala. Fluid (zrak) je stišljiv s izotermalnom promjenom, pV=const., pri čemu je p apsolutni pritisak.

where h is the membrane thickness, C1=E/[6(1+α)], E modulus of elasticity, α=C2/C1, C2 is the second material parameter. Fluid (air) is compressible with isothermal change, pV=const, where p is the absolute pressure.


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Postavljanjem odgovarajućih početnih uslova i uslova kontinuiteta, sistem jednačina (1)-(3) i (5)-(6) se rješava koristeći Runge-Kutta metodu četvrtog reda napisanu za ovu svrhu. Kao što je ranije rečeno, aplikacija je napisana u MathCAD softveru. Funkcije koje opisuju sistem diferencijalnih jednačina, a koje se koriste pri rješavanju Runge-Kutta metodom, date su na Slici 2 u MathCAD okruženju.

By setting appropriate initial and kinematic conditions, the system of equations is solved using fourth-order Runge-Kutta method programmed for this purpose. As already said, the application is written in MathCAD software. Functions, describing the system of differential equations, that are solved by Runge-Kutta method, are given in Figure 2. in MathCAD interface.

Slika 2. Dio iz MathCAD aplikacije – definisanje diferencijalnih jednačina

Figure 2. Section of the MathCAD application – definition of differential equations

Treba napomenuti da je u ovom istraživanju prethodno razvijena aplikacija za nestišljiv fluid [6] proširena modelom stišljivog fluida s izotermnom i adijabatskom promjenom. Također, implementiran je i algoritam koji uzima u obzir trenje između lopte i pritisnih ploča, kao u [7]. Proces je automatiziran, tako da je krajnji rezultat cjelokupna kriva sila-pomjeranje. Više detalja o samoj aplikaciji može se naći u [1].

It should be mentioned that the previously developed application for incompressible fluid [6] is extended in this work to account for compressible fluid with isothermal and adiabatic change. An algorithm to account for friction between plates and ball is also implemented, as in [7]. The solution process is automated such that the final result is the full force-displacement curve of the test. More details about application can be found in [1].

3. EKSPERIMENTALNA ISPITIVANJA Eksperimentalno istraživanje sastoji se od (i) mjerenja prečnika lopti, (ii) testa na pritisak i (iii) testova na zatezanje.

3. EXPERIMENTAL STUDY Experimental study consists of (i) measurements of the ball diameter, (ii) compression test and (iii) tensile tests.

Prečnik lopti izmjeren je koristeći koordinatnu mjernu mašinu „ZEISS“ Contura G2 aktiv na

Mašinskom fakultetu u Zenici (Slika 3.). Prije mjerenja prečnika lopti izmjeri se unutrašnji


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pritisak pomoću uređaja za mjerenje pritiska tipa Fox. Na taj način dobija se vanjski prečnik na određenom pritisku, što predstavlja polazno stanje za test na pritisak, ali i ulazne podatke za numeričko rješavanje (prečnik i počeno izduženje). The ball diameter is measured on coordinate machine ZEISS Contura G2 aktiv at Faculty of

Mechanical Engineering (Figure 3.). Prior to this measurement the pressure inside the ball is measured using a pressure device FOX. Thus, a diameter at a certain pressure is obtained, that is a starting point for the compression test, but also the input data for numerical solution (diameter and initial stretch).

a) b)

Slika 3. Koordinatna mjerna mašina Zeiss Contura G2 aktiv i ispitivana lopta Figure 3. Coordinate measuring machine Zeiss Contura G2 aktiv and tested ball

Testovi na pritisak izvršeni su na mašini „ZWICK ROELL“ u firmi Austroterm d.o.o. u Bihaću. Nakon provjere pritiska i prečnika lopte, lopta se postavi između dvije pritisne ploče i vrši se pritisna deformacija brzinom 1 m/min. Pored praćenja sile i pomjeranja, na loptu je priključen i uređaj za mjerenje pritiska tipa Fox. Sekvenca testa prikazana je na Slici 4.

Compression tests are conducted on „ZWICK ROELL“ tensile machine at Austroterm company in Bihać. Prior to the test, diameter and pressure in the ball are checked and the ball is compressed at speed 1 m/min. Besides monitoring the force and compression displacement, the ball is equipped with the pressure device FOX to record the ball internal pressure during the test. A test sequence is given in Figure 4.

Slika 4. Test na pritisak s mjerenjem pritiska u lopti [1] Figure 4. Compression test with pressure measurement [1]

Kao rezultat mjerenja dobiva se kriva napon-deformacija, koju je neophodno konvertovati u krivu sila-pomjeranje, kao što je objašnjeno u [1].

As a result, one can obtain stress-strain relationship that needs to be converted into force-displacement curve, as explained in [1].

Također, pomoću video zapisa i očitanja vrijednosti pritiska s uređaja za mjerenje pritiska u zavisnosti od vremena i/ili pomjeranja, dobiva se kriva pritisak-pomjeranje.


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Prva kriva koristi se za fino podešavanje ulaznih podataka u numeričkoj simulaciji, dok se drugi dijagram koristi kao kontrola procesa određivanja karakteristika materijala lopti. Na slici 5 dat je tipični dijagram sila-pomjeranje za jednu od ispitivanih lopti. Tačkasti podaci predstavljaju očitanja iz nekoliko ponovljenih testova s odgovarajućom paraboličkom aproksimacijom.

In addition, using the video recordings and pressure readings from THE pressure device (in time and/or compression displacement), one can obtain the pressure-displacement diagram. The former curve is used for fine tuning of input parameters in numerical simulation, whereas the latter one is used to control the process for determination of ball characteristics. Figure 5. shows a typical force-displacement diagram for a tested ball. Dots are individual pressure readings for several independent tests, shown together with parabolic regression curve.

Slika 5. Zavisnost sila-pomjeranje za test na pritisak Figure 5. Force-displacement relationship for compression test

Ispitivanje na zatezanje predstavlja verifikaciju kombinovane eksperimentalno-numeričke pro-cedure i biće detaljnije obrađeno u dijelu 5.

Tensile test is used for verification of the combined experimental-numerical procedure and will be explained in more detail in Section 5.

4. UTVRĐIVANJE KARAKTERISTIKA

MATERIJALA Ulazni podaci za numeričku analizu pomoću MathCAD aplikacije su: prečnik lopte, modul elastičnosti, debljina stijenke lopte, početno izduženje, broj proračunskih tačaka i kontaktni ugao. Početno izduženje predstavlja odnos između prečnika u napuhanom i nenapuhanom stanju, dok se kontaktni ugao definiše kao ugao čiji luk čini dio membrane u kontaktu s pritisnom pločom posmatran u nedeformiranom stanju. Vrijednosti početnih podataka za jednu od lopti dati su u Tabeli 1.

4. DETERMINATION OF MATERIAL

CHARACTERSITICS Input data for the MathCAD application are: ball diameter, modulus of elasticity, wall thickness, initial stretch, number of computational points and contact angle. The initial stretch is the ratio between the diameter of the inflated ball and that of the non-inflated one, whereas the contact angle is the angle of the membrane arc that is in contact with the compression plate in inflated state prior to the compression. Parameter values for a tested ball are given in Table 1.


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Tabela 1. Ulazni podaci za numeričku simulaciju Table 1. Input parameters for numerical simulation

Veličina/Parameter Vrijednost/Value Veličina/Parameter Vrijednost/Value Prečnik lopte, mm Ball diameter, mm 93.72

Broj proračunskih tačaka Number of computational points

300

Modul elastičnosti, MPa* Modulus of elasticity, MPa*

4 (3.2) Kontaktni ugao, °* Contact angle, °* 44 (53.5)

Debljina stijenke, mm* Ball thickness, mm* 1.5 (1.45) Početno izduženje, -

Initial extension, - 1.05

*veličine koje se mijenjaju/Parameters to be modified Pored pomenutih podataka, postavlja se i model materijala. U ovom slučaju korišten je Mooney-Rivlin model, ali postoji mogućnost korištenja tro-parametarskog Mooney-Rivlin modela, opšteg Mooney modela [9,10] te Hooke-ovog modela. Drugi parametar korištenog modela je zanemaren (α=0), tako da je u osnovi korišten neo-Hookov model. Također, postavlja se termodinamički zakon za fluid u lopti – koristi se izotermalni, pV=const, ali postoji mogućnost odabira i adijabatske promjene pVκ=const, za stišljive fluide, te nestišljiv fluid, V=const. U radu [1] je izvršena analiza uticaja pojedinih promjenljivih parametara na rezultate analize. Ustanovljeno je da na silu utiču svi parametri, ali je od pomentih parametara uticaj ugla α najveći, dok ostali parametri imaju ulogu 'dotjerivanja'. Na stepen kompresije najviše utiče ugao α, donekle početno izduženje, a ostali parametri imaju mali ili nikakav uticaj. Na odnos krajnjeg i početnog pritiska najznačajniji uticaj ima ugao α, dok je uticaj ostalih parametara veoma mali ili nikakav. Također je pokazano da koeficijent trenja od vrijednosti 0 (klizanje bez trenja) do kritične vrijednosti (nema klizanja) ima neznatan uticaj na rezultate analize [1], pa se u ovom radu neće analizirati. Mijenjajući podatke za modul elastičnosti, debljinu stijenke i kontaktni ugao, dolazi se do različitih krivih sila-pomjeranje, s krajnjim ciljem da se dobije dobro slaganje s eksperimentalnim rezultatima. Na Slici 6.a) prikazane su eksperimentalna i odgovarajuća numerička kriva nakon podešavanja parametara. Vrijednosti koje zadovoljavaju prethodni proračun su dati u Tabeli 1. u zagradama. Kao kontrola procesa upoređen je i unutrašnji pritisak. Zavisnost promjene pritiska od pomjeranja data je na Slici 6b.

Besides aforementioned parameters, a material model is also set. Mooney-Rivlin model is used here, but there is option to use three-parameter Mooney-Rivlin, general Mooney [9,10] and Hookean model. The second model parameter is neglected (α=0), so, basically, the model used is neo-Hookean. The thermodynamic law for the fluid inside the ball is set to be isothermal, pV=const, but one can also use adiabatic, pVκ=const, for compressible fluids, and incompressible model, V=const. The detailed analysis of the influence of aforementioned parameters on results is given in [1]. It is shown that all parameters affect the force, but the most prominent is the contact angle. Other parameters are usually used for fine-tuning. Compression ratio is most affected by the contact angle and somewhat by initial stretch, whereas the influence of other parameters can be neglected. The ratio between final and initial pressure is most affected by the contact angle with other parameters having small influence if any. It is also shown that the friction between plates and the ball, in the range of friction coefficient between 0, ie. slip condition, and the critical value, ie. no-slip condition, has neglegable influence on the results [1] and will not be analysed here. By varying the values of modulus of elasticity, wall thickness and contact angle, one can obtain different load-displacement curves, with the aim to obtain a good agreement with the experimental results. Figure 6a shows the experimental and corresponding numerical curve after fine-tuning of the parameters. Parameter values that satisfy the final calculations are given in Table 1 (see values in brackets). As a procedure control, the internal ball pressure is also compared with the comparison, as given in Figure 6b.


196

Treba napomenuti da se u MathCAD aplikaciji dobivaju i vrijednosti izduženja/deformacija i napona u dva glavna pravca, te profil lopte u toku testa (Slika 7).

It has to be mentioned that the MatchCAD application also provides the stretch/deformation and stress histories in the two principal directions and ball profile (Figure 7).

a) b) Slika 6. Uporedni rezultati eksperimenta i numeričke analize: a) sila-pomjeranje, b) pritisak-

pomjeranje Figure 6. Comparison between experimental and numerical results: a) force-displacement, b)

pressure-displacement

a) b)

Slika 7. Dodatni rezultati numeričke analize: a) glavna izduženja, b) profil lopte Figure 7. Additional numerical results: a) principal stretches, b) ball profile

5. VERIFIKACIJA REZULTATA Verifikacija rezultata eksperimetnalno-numeričke analize urađena je pomoću testova na zatezanje. Iz materijala lopti su izrađene epruvete prema standardu ASTM D 638-03 [9] i ispitivane na mašini „Zwick Roell“ u firmi Car Trim d.o.o. u Žepču. Prije ispitivanja izmjerene su debljine stijenki za sve epruvete. Na slici 8. date su inženjerske krive napon-deformacija za ispitivanu loptu. Imajući u vidu rezultate numeričke analize, gdje se pokazalo da izduženja ne prelaze vrijednosti 1.4, u procjeni modula elastičnosti uzimaju se samo deformacije do 40% (Slika 7b).

5. VERIFICATION OF RESULTS Verification of the results of this combined experimental-numerical analysis is carried out via tensile tests. Specimens are cut from the ball material according to the ASTM D 638-03 [9] and tested on the „ZWICK ROELL“ machine at the company Car trim d.o.o. company in Žepče. Prior to testing the thickness for all specimens is measured. Figure 8. gives engineering curves for the ball tested. Having in mind numerical results, with stretches below 1.4, only the first part of the curves is considered with deformations below 40% (Fig. 7b).


197

a) b) Slika 8. Inženjerske krive napon-defromacija za materijal ispitivane lopte

Figure 8. Engineering stress-strain curves for the ball material U svrhu dobivanja relevantnijih podataka, debljina stijenke lopte mjerena je i na ostalim dijelovima isječenih lopti. Za posmatranu loptu dobivene su vrijednosti debljine stijenke od 1.52 mm i modula elastičnosati od 3.1 MPa.

To obtain more convenient results the wall thickness is measured at other parts of the ball material. For the ball analysed in this paper measured wall thickness is 1.52 mm, and modulus of elasticity evalueted from the Figure 5b is 3.1 MPa.

6. ZAKLJUČCI Uzimajući u obzir kvalitativne rezultate u pogledu krivih sila-pomjeranje i pritisak-pomjeranje (Slika 6), te kvantitativnih vrijednosti za modul elastičnosti (3.2 MPa and 3.1 MPa) i debljinu stijenke (1.45 mm i 1.52 mm), može se zaključiti da je metod pouzdan za procjenu mehaničkih osobina sfernih elastičnih objekata. Također, pokazano je da Mooney-Rivlin/neo-Hookean model materijala uspješno opisuje ponašanje materijala od kojih su lopte napravljene. Treba, ipak, napomenuti da je uvijek neophodno izvršiti dodatnu kontrolu eksperimenta, s obzirom da različite kombinacije ulaznih parametara u numeričkoj simulaciji mogu dovesti do istog rješenja u pogledu krive sila-pomjeranje. U ovom radu to je urađeno praćenjem pritiska unutar lopte za razliku od uobičajenog pristupa u literaturi, tj. video praćenja kontaktne površine između lopte i pritisne ploče. Ukoliko dodatni test nije moguće zadovoljiti, postoji mogućnost da model materijala nije prikladan. Ovo je pokazano u radu [1] gdje Mooney-Rivlin model nije doveo do dobrog slaganja krive pritisak-pomjeranje, iako su se eksperimentalna i numerička kriva sila-pomjeranje odlično slagale. Umjesto Mooney-Rilvlin modela implementirao se i primijenio opšti Mooney model materijala [10,11] sa zadovoljavajućim rezultatima. Ovo istraživanje je trenutno u toku.

6. CONCLUSIONS Taking into consideration qualitative results in terms of the load-displacement and pressure-displacement curves (Figure 6.) and quantitative results for the modulus of elasticity (3.2 MPa vs. 3.1 MPa) and wall thickness (1.45 mm vs. 1.52 mm), one can conclude that the presented method is reliable tool for determination of mechanical charactersitics of the spherical elastic objects. It is also demonstrated that the Mooney-Rivlin/neo-Hookean material model succesfuly described the ball material behaviour. However, it has to be noted that the additional control tests are necessary, since different combinations of input data can lead to the same results in terms of load-displacements curves. In this work the control is carried out via monitoring internal pressure unlike the common procedure in literature, where the contact area is recoreded using video equipment. If the additional control test is not possible, there is a possibility that the material model applied is not correct. This is demonstrated in [1], where the application of Mooney-Rivlin material model does not lead to the satisfactory pressure-displacement curve, although experimetnal and numerical force-dispalcement curves are in agreement. Instead, the general Mooney material model [10,11] is implemented and applied with satisfactory results. This research is currently in progress.


198

7. ACKNOWLEDGEMENTS Autori žele da se zahvale menadžmentima firmi Austrotherm, Bihać, i Car Trim, Žepče, gdje su izvedena ispitivanja na pritisak i zatezanje, respektivno, te prof. dr. Samiru Lemešu za dimenziona mjerenja na koordinatnoj mjernoj mašini.

7. ACKNOWLEDGEMENTS The authors would like to thank the managements of the companies Austrotherm d.o.o, Bihać, and Car Trim d.o.o., Žepče, where the compression tests and tensile tests are carriend out, respectively. We would also like to thank prof. dr. Samir Lemeš for the help with dimensional measurements on coordinate machine.

8. REFERENCES [1] Kargić M.: Određivanje mehaničkih

karakteristika materijala elastičnih lopti trestom na pritisak, MSc thesis, Univerzitet

[2] Feng,W.W.,Yang,W.H.: On the contact problem of an inflated spherical nonlinear membrane, Transactions of the American Society of Mechanical Engineers: Journal of Applied Mechanics 40,209-214, 1973.

[3] Yang W.H., Feng W.W.: On Axisymmetrical Deformations of Nonlinear Membranes, Journal of Applied Mechanics, Vol. 37, Trans. ASME, Vol. 92, Series E, p. 1002-1011., 1970.

[4] Liu,K.K.,Williams,D.R., Briscoe,B.J.: Compressive deformation of a single microcapsule, PhysicalReview E 54,6673-6680, 1996.

[5] Lardner,T. J., Pujara, P.: Compression of spherical cells, Mechanics Today 5, 161-176, 1980.

[6] Parsa, HK: The Development of a Novel Surrogate Lung Material for the Quantitative Prediction of Impact Trauma in Human Lungs, PhD thesis, University College Dublin, 2012

[7] N. Kumar, A. DasGupta: On the conact problem of an inflated spherical hyperelastic membrane, International Journal of Non-Linear Mechanics, 57, 130-139, 2013.

[8] ASTM D 638-03, Standard Test Method for Tensile Properties of Plastics

[9] PTC MathCAD, https://www.ptc.com/en/products/mathcad, visited on 2018-10-10.

[10] M. Mooney, Theory of large elastic deformation, J. Appl. Phys. 11, 582, 1940.

[11] R. Mangan, M. Destrade: Gent models for the inflation of spherical baloons, International journal of non-linear mechanics, 68: 52-58, 2015.

Coresponding author: Aleksandar Karač Polytechnic Faculty, University of Zenica Email: [email protected] Phone: +387 32 44 44 20

Mašinstvo 4(15), 199 – 206, (2018) A. Kubat et al.: DETERMINING RECALIBRATION…

199

DETERMINING RECALIBRATION INTERVAL FOR LABORATORY EQUIPMENT

UTVRĐIVANJE INTERVALA REKALIBRACIJE

LABORATORIJSKE OPREME

Amir Kubat1, Senad Pašalić1, Alma Bečirović1, Samir Lemeš2, Murćo Obućina3 1LIND - Laboratory for product safety testing Zenica 2University of Zenica 3University of Sarajevo Keywords: calibration, recalibration interval, metrology Ključne riječi: kalibracija, interval rekalibracije, metrologija Paper received: 17.10.2018. Paper accepted: 20.12.2018.

Professional paper SUMMARY This paper describes the application of international standards, recommendations and guides, as well as other input data, to determine the interval of recalibration of laboratory equipment in the laboratory for testing the product safety testing LIND in Zenica, Bosnia and Herzegovina. An example of a pressure sensor on a 4-axis device for measuring the geometry of furniture, a detailed analysis of the recalibration interval was performed, which had to be shortened from 5 to 3 years.

Stručni rad REZIME Ovaj rad opisuje primjenu međunarodnih standarda, prepruka i vodiča, kao i drugih ulaznih podataka, za određivanje intervala rekalibracije laboratorijske opreme u laboratoriji za ispitivanje sigurnosti proizvoda LIND u Zenici, Bosna i Hercegovina. Na primjeru jednog senzora pritiska na 4-osnom uređaju za mjerenje koordinata geometrije namještaja, izvršena je detaljna analiza intervala rekalibracije, koji je morao biti skraćen sa 5 na 3 godine.

1. INTRODUCTION A number of authors investigated this topic for different measuring equipment, from torque meters to atomic clocks. Vasilevskyi in [1] presented a method for determining the recalibration interval of measurement tools, based on the measurement uncertainty analysis of experimental data with the metrological certification. He used the results of testing procedures to determine the recalibration interval for equipment measuring motor torque. Natalinova et al. in [2] presented the calibration interval calculation of the potentiometer according to the verifications for the 4 year period in the aviation plant. The calibration interval increased according to the calculation of its reliability and stability of metrological characteristics. Nunzi et al. in [3] compared three different methods for the establishment of optimal

calibration intervals of atomic clocks: one based on a stochastic model, the others pertained to the class of the reactive methods, determining the optimal interval based on the last calibration outcomes. Wang et al. in [4] proposed an approach for evaluating the optimal calibration interval of automatic test equipment on the basis of the metrology chain. The calibration interval of a single instrument is determined by a grey prediction model, using out of tolerance-calibration matrix to calculate the metrology contribution rate, according to the multi-signal flow model. The process of determining calibration intervals is a complex mathematical and statistical process requiring accurate and sufficient data taken during the calibration process. There appears to be no universally applicable single best practice for establishing and adjusting the calibration intervals. This has created a need for better


200

understanding of the calibration interval determination. As no single method is ideally suited for the whole range of measuring instruments, some of the simpler methods of assigning and reviewing the calibration interval and their suitability for different types of instruments are covered in OIML Guide [5] and in NCSL Recommended Practice [6]. The NCSL Recommended Practice RP-1 [6] provides a guide for the establishment and adjustment of calibration intervals for equipment subject to periodic calibration. It provides information needed to design, implement and manage calibration interval determination, adjustment and evaluation programs. Bare in [7] simplifed the methods from [6] for laboratories with limited calibration histories. His algorithm uses a calibration laboratory management database with historical fields for "out of tolerance" or "in tolerance" conditions along with the degree of any out of tolerance condition. A drawback to this is that in most cases data entry is required to indicate the degree of out of tolerance. This can be done by either entering the calibration results as a whole into the database or through the entry of specific out of tolerance conditions into the database [7]. Zhenlin et al. in [8] performed the dynamic optimization of measuring instrument calibration interval, predicting the history calibration data by modelling. They used the improved moving average method to predict the development trend of parameters, BP neural network to compensate the predicted residual sequence, and gave the improved MA-BP prediction model to optimize the calibration interval dynamically. 2. ABOUT THE LABORATORY FOR

PRODUCT SAFETY TESTING "LIND" ZENICA

The Laboratory LIND was created as a result of the project MENTOR financed from the European Union Development Funds for Bosnia and Herzegovina. The project implementation was co-funded by the City of Zenica, Ministry of Economy of the Zenica-Doboj Canton, Regional Development Agency REZ, and the Federal Ministry of Development, Entrepreneurship and Crafts. Initially, the laboratory performed only furniture testing [9], and through the time, it has grown into the Laboratory for Product Safety Testing, including the testing of children's playgrounds.

The project MENTOR 2, expanded the testing area to the building construction elements (doors, windows and facade elements). Figure 1 shows the interior of the laboratory.

Figure 1. Laboratory for furniture testing [9]

2.1. Equipment maintenance The laboratory management and staff in LIND keeps control of the equipment conditions within their responsibilities. In order to maintain the proper conditions of the laboratory equipment, a maintenance plan and a calibration plan for each year is prepared according to adopted forms, in accordance with the manufacturer's instructions, OIML D10 Guidelines for the determination of calibration intervals of measuring instruments, examples of recommended calibration intervals given by BATA (Accreditation Institute of Bosnia and Herzegovina), and Appendix A of the standard BAS EN ISO 10012-1:2004 [10]. These plans are developed in accordance with the procedures of Equipment Maintenance and Equipment Calibration. Testing machines and equipment are handled by trained and authorized laboratory staff. Each test device and equipment, is accompanied with a brief instruction manual. 2.1. Equipment documentation For all machines, equipment, and, if necessary, parts of this equipment, the basic data is recorded in the official form. Records of overhauls and repairs of machines and equipment are recorded in the form "Plan and Equipment Maintenance Record" and are kept with the appropriate device record. Records of the resulting failures of calibration equipment are recorded on the form "Record of incurred defects in machinery and equipment". For every piece of equipment, a traceability chart is provided in the appropriate form, which shows the calibration traceability of this device to the


201

national or international standards. Traceability charts are kept with the appropriate lists. For all devices that are calibrated, a record of the calibration history is recorded in the form "Plan and Record of Equipment Calibration". Completed and updated form of the calibration history of the machine/equipment/standard is part of the official documentation and serves as the documented definition of the recalibration period. Calibration certificates for test machines and equipment are stored in the registry "Calibration Certificates of Machines and Equipment". Laboratory personnel is responsible for the correctness and condition of testing machines and equipment in the laboratory. If equipment or part of the equipment is damaged during the use, the personnel shall comply with the Maintenance procedure for machinery and equipment. Any piece of equipment or device that has suffered an overload or is found to be defective, is handled in accordance with the Maintenance procedure for machinery and equipment, and marked with the label "OUT OF ORDER". 2.2. Equipment calibration For each testing machine and equipment, there are appropriate Plan and records on performed calibrations, in which the following elements are recorded, monitored, checked and analysed: - Equipment name, inventory number,

manufacturer; - Measurement range; - Calibration range; - Measurement uncertainty; - Date of valid calibration; - Recommended calibration period from the

device manufacturer for 100% utilization; - Equipment utilization (%); - Valid period of regular calibration (years); - Date of extraordinary calibration; - Description of realized jobs; - Date of planned calibration; - Person who performed the calibration / ID

code of the report / certificate; - Responsible person.

Each test device has a label with the latest calibration dates and the certificate number. Equipment checks between two regular calibrations are performed in the framework of additional quality assurance as defined by the procedure of Quality Assurance of Testing and Calibration Results. The test machines in the laboratory which are operated by software have computer programs LAB CONTROL and BERT PRO installed, which are used to perform the tests. No other software is allowed to be installed on these computers. Access to computers and equipment is granted only to LIND staff. 3. EQUIPMENT MAINTENANCE Quality Manager and Laboratory Manager of LIND are in charge to make a maintenance plan and equipment maintenance record at the end of the current year for the next year in the form, "Plan and Record of Equipment Maintenance", approved by the CEO of the Agency to which Laboratory belongs. Only periodic maintenance of the equipment or its parts is planned, as stated in the technical documentation provided by the laboratory equipment manufacturer. Table 1 shows an example of the form "Plan and Record of Equipment Maintenance", in which the updating, planning, recording and checking the accuracy of test equipment with calibrated control devices is performed once every six months. This form records the performed tasks within the planned and unplanned maintenance of the equipment. If there is a deviation from the plan and record of equipment maintenance (e.g. due to objective reasons of an approved internal/external supplier, due to write-off of equipment or parts of equipment, procurement of new equipment or part of equipment, ...), the Laboratory Manager makes a revised plan and record of equipment maintenance in the same way as the plan and record of equipment maintenance at the end of the current year for the next year.

Table 1. Headers of the form "Plan and Record of Equipment Maintenance"

No.

Name of equipment or its part

Description of tasks to be

done

Maintenance interval

recommended by the

manufacturer

Final term for

performing the task

Internal checking

device

Date of performing

the task Performer Responsible

person


202

During the managerial review, the status of the test equipment is analysed based on the reports prepared according to the "Plan and Record of Equipment Maintenance", which has the effect of improving the quality management system in the Laboratory. 3.1. Maintenance preparation Internal maintenance activities of the equipment are entrusted to LIND personnel in accordance with the procedure for reviewing the contract and the instructions for the functioning of the protocol. These activities are carried out in accordance with the adopted maintenance schedule. In the case of requests for maintenance of the equipment or its servicing, where external suppliers and executors are needed, the LIND Manager submits the procurement request of the given service to the General Affairs Division. 3.2. Irregular maintenance In all cases of sudden failure in the equipment, equipment operators also make records in the form "Record of Equipment Faults", and then inform the manager or technical manager of the LIND about the resulting fault, and they verify it in the appropriate form cell. If the laboratory equipment failure occurs during the warranty period, the CEO of the Agency shall be notified, who then contacts the authorized service by means of the General Affairs Division. After the repair, the service is obliged to issue a certificate of the equipment. For the repair of equipment with the warranty period expired, approved suppliers or LIND services may be engaged, if any. The minutes about the performed repairs and servicing of the equipment, are compiled and signed by the representative of the supplier (repair / servicing equipment technician) and the (technical) manager of LIND. 3.3. Additional quality assurance of test results Additional quality assurance of test results is possible in several ways: - additional equipment checking through

regular maintenance every six months, as well as a device reliability check through an analysis of the period of regular equipment calibration;

- internal quality control service; - inter-laboratory comparison; - participation in laboratory testing programs

by comparing test results of related

laboratories (simpler procedure than inter-laboratory comparison);

- repeat testing using the same or different methods;

- re-examining the same / similar objects; - conducting internal staff training for those

methods that were not carried out for a certain period of time in the laboratory;

- regular check of the edition of the standard; - correlation of test results for different

characteristics of the tested sample / subject of the test.

- by repeating the test using the same or different methods for methods where this is possible according to the standard in the framework of internal training of LIND staff.

In order to carry out the examinations for internal training, identical steps are undertaken as for regular commercial tests, with additional analysis of the test results in accordance with the defined criteria for the admissibility of test results. Testing will be repeated where possible, according to standards, where the standard deviation of these measurements and the comparison of the obtained test results according to the parameters are given in the test standards. In order to carry out the internal training, it is obligatory to conduct repetition of tests for those methods for which measurement uncertainty is required with the calculated uncertainty budget. In case a LIND supervisory staff's suspects the results of the investigation, a re-examination on the same subject shall be carried out, if possible. In this case, the presence of the LIND Manager is required during the entire test process.

Figure 2. Laboratory equipment

All the above-mentioned internal quality assurance measures for testing results in the LIND laboratory (except PT/ILC schemes implemented separately), are planned and monitored in the form "Plan and record of internal quality assurance / result quality control". The planning and recording of internal quality assurance / quality control measures is


203

reviewed on a regular (and, as appropriate, extraordinary) review by the management. If it is determined after the analysis that the data are out of the defined criteria, corrective or preventive measures are being taken. 4. EQUIPMENT CALIBRATION 4.1. Creating a Plan and Equipment Calibration Records LIND holds lists of equipment that are calibrated externally. These lists are attached to the appropriate specific procedures. The technical director of LIND, at the end of the current year, is planning a calibration plan for equipment for the next year in the form "Plan and Record of Equipment Calibration", for both internally or externally calibrated equipment. The plan is approved by the Agency CEO. If there is a deviation from the plan and equipment calibration records (due to the write-off of the equipment or part of the equipment, i.e. the purchase of new equipment or part of the equipment, or due to the inability of an external approved supplier to perform the calibration in the planned term, or uninsured financial assets by the management of LIND or the Agency,...) the LIND Manager makes a revised plan and records the equipment calibration. 4.2. Planned Calibration Planning and recording equipment calibration in the Laboratory are conducted in the form "Plan and Record of Equipment Calibration". The form defines elements that are monitored, analysed and periodically checked to precisely define the calibration period with each individual equipment and parts of the LIND equipment, which are: - Equipment name, inventory number,

manufacturer; - Measurement area; - Calibration area; - Measurement uncertainty; - Date of valid calibration; - Recommended calibration period from the

device manufacturer for 100% utilization; - Equipment utilization (%); - Planned period of regular calibration; - Date of extraordinary calibration; - Description of tasks; - Calibration executor / Identification code of

the report / certificate; - Responsible person. When planning the period of regular calibration and maintenance of equipment, one must always

follow the guidelines defined in the documents: OIML D10 Guidelines [5], BATA recommend-ation as a mandatory document, recommen-dations of the manufacturer of equipment and some examples of recommended calibration intervals, as well as in the Appendix A of the standard BAS EN ISO 10012:2004. The analysis and updating of the form "Plan and record of equipment calibration" is performed as compulsory every six months on a regular basis, as well as in the cases of increased number of furniture tests. Following the analysis of all elements, a report on the status of the test equipment in the laboratory is made. During the managerial review within the framework of the analysis item eleven, which refers to resources, i.e. equipment, the use of equipment is analysed in order to define or revise the calibration terms of the equipment based on the analysis and the reports made according to the "Plan and records of equipment calibration". The Laboratory also envisages the extraordinary / unplanned calibration of equipment, which is carried out in the following cases: - when the results of the test are suspected

because they deviate more than usual, and in case when they are not caused by the characteristics of the test subject or the work of the examiner,

- when there are defects in equipment or parts of equipment that are otherwise calibrated,

- changes in the performance of the test equipment as a result of its servicing,

- purchase of new equipment and its first calibration,

- large deviations in test results due to the intensive use of some equipment and machines.

The frequency of use of equipment and machines (Table 2) is monitored and recorded at each individual test through the records of equipment used in the work order for testing, as well as in the form "Plan and records of equipment maintenance". Calibration of equipment that is performed as the preparation of test equipment, before each individual or pre-series test, is not subject to this procedure. These calibrations are performed according to the instructions for handling the equipment and/ or the instructions for carrying out the test according to the testing standard in order to ensure the quality of the test results.


204

Table 2. Times of equipment use

No. Equipment name

ID Manufacturer

Date of valid calib-ration

PI/ 14/13

PI/ 01/14

PI/ 08/13

PI/ 18/13 ... ...

Total time used

(hours)

1.

Pressure force sensor, on 4-axis machine - pneum. cyl. - side; Step length: L=500 mm, Diameter: D=63 mm; Serial no.: 41011207 ID no.: 119 Hegewald & Peschke

17.07. 2013. 5 min. 5 min. 0 min. 0 min. ... ... 87 h

50 min.

5. DETERMINING RECALIBRATION

INTERVAL The recalibration period (planned calibration) is defined for the equipment to be calibrated, and if the equipment is part of the legal metrology, the defined recalibration period (indicated in the valid calibration certificate) is taken into consideration. Based on the recalibration period, the date of the planned calibration is determined and entered in the form "Plan and Record of Equipment Calibration" for each year. When planning and determining the period of calibration and maintenance of equipment

(Example - Table 3), according to the guidelines and recommendations, one must take into account the following factors: a) Recommendation of the manufacturers of

measuring and testing equipment; b) Expected frequency and conditions of use; c) Environmental impact; d) Required measurement uncertainty; e) Settings of the individual instruments, or

changes that occur in them; f) Summary or published data about the same

or similar devices.

Table 3. The calibration period calculated by the utilization of the equipment

No. Equip-ment ID

Date of

valid calib-ration

Manufacturer's recommendations Local laboratory parameters

Calib-ration

interval

Wor

king

tem

p.

(°C

) R

el. h

umid

ity

(%)

Mai

nten

ance

per

iod

Cal

ibra

tion

inte

rval

fo

r 100

% c

apac

ity

per s

hift*

Rel

. hum

idity

(%

)

Mai

nten

ance

per

iod

Cal

ibra

tion

inte

rval

fo

r 100

% c

apac

ity

hif*

Tota

l usa

ge ti

me

(h

)

Usa

ge ra

tio a)

(%

)

1 2 3 4 5 6 7 8 9 10 11 12 13

1.

Pressure sensor ID no. 119 Hegewald & Peschke

17.07. 2013.

10 - 30 °C

10-85%

1 year

1 year* for 265 working days per year i.e. 2120 h

from min. 15,7 °C to

max. 23,8 °C

from min. 48,8 % to max. 51,5 %

6 mont

hs

87,83 4,14 24,15

In addition to the above-mentioned factors for determining the equipment calibration interval in LIND, a simplified analysis of the calibration

interval (NCSL Recommended Practice RP-1) is taken into account, simplified and calculated.


205

The last calibration has the greatest contribution/ influence. (IK)n = (IK)s x (W1 x X + W2 x Y + W3 x Z) Where: (IK)n = new calculated calibration interval; (IK)s = the old calibration interval; W1 = impact factor of the last calibration; W2 = impact factor of the second calibration; W3 = impact factor of previous calibration; X = multiplier related to the result of the last calibration; Y = multiplier referring to the result of the second calibration; Z = multiplier referring to the result of the previous calibration; The final, adopted new calibration interval for all LIND equipment is determined taking into account the following: - date of valid calibration of LIND equipment; - the equipment calibration interval recom-

mended by equipment manufacturer - (IK) man;

- calculated calibration interval for the use of LIND equipment - (IK) LIND;

- equipment calibration interval defined by another laboratory of the same activity that owns the same type of equipment from the same supplier - LIN Zagreb - (IK) LIN;

- defined - old interval of calibration of LIND equipment - (IK) s;

- the calibration interval of LIND equipment determined according to the NCSL RP-1 method - (IK) n;

- calculated average interval of calibration of LIND equipment - (IK) avg;

- adopted new interval of calibration of LIND equipment - (IK) new.

(IK)n for conditions in LIND is calculated as follows: (IK) s x (W1 x X) where: W1 = 0.8; X = 1 The new adopted equipment calibration interval in LIND is calculated as follows: (IK)avg=[(IK)man+(IK)LIN+(IK)s+(IK)n]/4 Based on calculated (IK)avg, a new calibration interval is adopted: (IK)new (Table 4).

Table 4. The new adopted calibration interval

No. Equip-ment ID

Date of

valid calib-ration

Recom-mended

calibration interval by

manufacturer for 100%

utilisation in one shift*

1 year (265 working days per year i.e.

2120 h) (IK)man.

Calcu-lated

calibr. interval

by equip-ment utili-sation (%)

Calibr. interval

defined by similar

laboratory (year)

(IK)LIN

Old calibr.

interval of LIND equip-ment (year) (IK)s

Calibr. interval

by NCSL RP-1 (year) (IK)n

Calcu-lated

average calibr.

interval (year)

(IK)avg

Adopted new

calibr. interval (year)

(IK)new

1 2 3 4 5 6 7 8 9 10

1.

Pressure sensor ID no. 119 Hegewald & Peschke

17.07. 2013. 1 24,15 5 5 4 3,75 3

On the basis of a detailed analysis of all the above factors for determining the calibration interval for LIND equipment, defined equipment calibration intervals, records and data (values) data in the free table form will be defined. The

Plan and Records of equipment calibration will be updated accordingly in the future in LIND laboratory. The new form will contain the following data: - Measurement range


206

- Calibration range - Measurement uncertainty - Date of valid calibration - Recommended calibration interval as

recommended by the manufacturer for 100% equipment utilization (%)

- Valid interval of regular calibration - The date of irregular calibration - Description of tasks realized - Date of planned calibration - Person who performed the calibration / ID

code of the report / certificate - Responsible person 6. CONCLUSION Taking into account a number of influences and parameters, a new recalibration interval for one piece of laboratory equipment was determined. The calibration interval was reduced from 5 to 3 years, according to the influence factors, such as utilisation rate, experiences from similar laboratories, manufacturer's recommendations, ISO standard, NCSL recommendation RP-1, OIML guide D10, etc. The methodology can and will be used for all other devices and laboratory equipment which has to be calibrated. 7. REFERENCES [1] Vasilevskyi O.M. (2014) Methods of deter-

mining the recalibration interval measure-ment tools based on the concept of un-certainty. Technical Electrodynamics, 6, pp 81-88.

[2] Natalinova N., Ilina N., Frantcuzskaia, E. (2016, June). Calibration Interval Adjust-ment of a Measuring Instrument in Indus-tries During Long-term Use. In IOP Conference Series: Materials Science and Engineering (Vol. 132, No. 1, p. 012029). doi:10.1088/1757-899X/132/1/012029

[3] Nunzi E, Panfilo G, Tavella P, Carbone P, Petri D (2005) Stochastic and reactive methods for the determination of optimal calibration intervals. IEEE Transactions on Instrumentation and Measurement 54 (4) 1565-1569. doi: 10.1109/TIM.2005.851501

[4] Wang, J., Zhang, Q., & Jiang, W. (2017). Optimization of calibration intervals for automatic test equipment. Measurement, 103, pp 87-92. doi:10.1016/j.measurement. 2017.01.062

[5] ILAC (2007) Guidelines for the determi-nation of calibration intervals of measuring instruments, ILAC-G24:2007 / OIML D 10:2007 (E).

[6] NCSL (2010) Establishing and Adjustment

of Calibration Intervals. Recommended Practice RP-1.

[7] Bare A (2006) Simplified Calibration Interval Analysis. NCSL International Workshop and Symposium. https://www. isobudgets.com/pdf/calibration-interval-analysis/simplified-calibration-interval-analysis.pdf (16.12.2018)

[8] Zhenlin C, Fang Z, Xiao Z (2014). Combined Forecast of Calibration Interval Based on Linear Trend Model and Neural Network. Applied Mechanics & Materials. Issue 635-637, pp 662-665. doi:10.4028/ www.scientific.net/AMM.635-637.662.

[9] Lemeš S, Jašarević S, Kubat A (2015) Quality Infrastructure For Furniture Testing In Bosnia&Herzegovina, 2nd international conference "Functioning and improvement of management systems" (P. Nowicki, T. Sikora, editors), pp 95-102, ISBN 978-83-942362-5-0, Niepołomice, Poland

[10] BAS EN ISO 10012:2004 Measurement management systems - Requirements for measurement processes and measuring equipment,

Coresponding author: Samir Lemeš University of Zenica, Polytechnic Faculty Email: [email protected] Phone: +387 32 449 147

Mašinstvo 4(15) 207 – 211 (2018) D. Spahić et al.: BETTER RESULTS OF CRANIOPLASTY….

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AN EXAMPLE OF CRANIOPLASTY WITH THE ASSISTANCE OF 3D PRINTING TECHNOLOGY: A CASE REPORT

PRIMJER KRANIOPLASTIKE UZ ASISTENCIJU TEHNOLOGIJE 3D

PRINTANJA: PRIKAZ SLUČAJA

Denis Spahić, Hakija Bečulić Univerzitet u Zenici Politehnički fakultet Kantonalna bolnica Zenica Odjel za neurohirurgiju Ključne riječi: Kranioplastika, 3D printanje, izrada kalupa, proteza kranijalnog svoda Keywords: Cranioplasty,3D printing, mold-making, cranial-vault prosthesis Paper received: xx.xx.xxxx. Paper accepted: xx.xx.xxxx.

Stručni rad REZIME Kranioplastika je hirurška popravka koštanog defekta lobanje koji je ostao nakon ozbiljne povrede ili prethodne operacije. Uobičajna svrha ove intervencije je zaštita moždanog tkiva, smanjenje lokalnog bola i poboljšanje estetike kranijalnog svoda. Kranijalne proteze mogu biti napravljenje od različitih materijala: autologne kosti, titanijuma, keramike i polimera. Njihova proizvodnja je skupa i često zahtijeva kompleksne intraoperativne procese, što ponekad rezultira slabim estetskim rezultatima kod velikih i kompleksnih defekata. Ovaj rad, na konkretnom primjeru, predstavlja metod za izradu implanta po mjeri pacijenta od polimetil metakrilata, uključujući trodimenzionalnu rekonstrukciju baziranu na CT snimcima, tehnologiju 3D printanja i izradu kalupa od zubarskog gipsa.

Professional paper

SUMMARY Cranioplasty is the surgical repair of a bone defect in the skull that is left behind after a severe injury or previous operation. It is usually done to protect underlying brain tissue, reduce local pain and to improve the cranial vault aesthetics. Cranial prostheses can be made from different types of materials: autologous bone, titanium, ceramics and polymers. Their production is costly and often requires complex intraoperative processes which sometimes cause poor aesthetic results in large and complex defects. Using a real case, this paper presents a customised polymethyl methacrylate implant production method which involves three dimensional reconstruction based on CT scans, technology of 3D printing and mold-making from dental plaster.

1. UVOD Nekoliko mogućih razloga za gubitak kontinuiteta kostiju kranijalnog svoda su: ozbiljna povreda glave, dekompresivna kraniotomija ili recidiv tumora. Ova vrsta defekta je zaista teška za pacijenta jer često uzrokuje fizičke (glavobolju, konfuziju, epilepsiju), ali i mentalne probleme (razdražljivost, depresija) [1]. Estetske abnormalnosti uzrokovane defektom lobanje također su jedan od glavnih problema, posebno kod mlađih pacijenata. Ljudsko tijelo nije u stanju regenerisati izgubljeni dio lobanje, ali se on može rekonstruisati kroz multidisciplinarni pristup i postavljanje proteze. Medicinski termin za ovu neurohiruršku proceduru je kranioplastika i prakticira se od 3000. godine p.n.e. Postoji nekoliko materijala koji se koriste za izradu kranijalnih proteza: koštani transplantati, metali, biosintetički materijali kao što su keramika i smola. Metil metakrilat je reaktivna smola čija je formula CH2 = C(CH3) COOCH3, a

1. INTRODUCTION Severe head injury, decompressive craniotomy or tumor recesion, are all possible reasons for lack of continuity of the cranial vault bones. This kind of defect is really hard for a patient since they often cause physical (headache, confusion, epilepsy) as well as mental problems (irritability, depression) [1]. Aesthetic abnormalities caused by skull defects are also one of the major problems, especially among young patients. It is not possible for human body to regenerate a lost part of a skull, but, it can be reconstructed through a multidisciplinary approach and the placement of a prosthesis. The medical term for this neurosurgical procedure is cranioplasty and it has been practiced since 3000 BC. There are several materials which are used for cranial prostheses: bone grafts, metals, biosynthetic materials such as ceramics and resin. Methyl methacrylate is a reactive resin with the formula CH2=C(CH3)COOCH3 which was used for the first time in 1941; since then


208

prvi put je korištena 1941. godine; od tog vremena u operacionoj sali korišteni su i mnogi drugi derivati [2]. Proteze od polimetil metakrilata (PMMA) se prave intraoperativno i zahtijevaju pripremu dvokomponentne smjese, kao i podešavanja implantata - oblikovanje za vrijeme operacije što rezultira produženjem trajanja operacije. Kod velikih i složenih defekata, intraoperativna podešavanja implantata, naročito oblikovanje nepravilne krivine rukama, mogu rezultirati lošim estetskim rezultatima. PMMA ima mnoge prednosti: ne postoji potreba za donorom, nije previše skup, lagan je, otporan, inertan, radiolucentan, ne-feromagnetski i stabilan. Nedostaci su u tome što ima nizak stepen prijanjanja za okolno tkivo i može izazvati reakcije tkiva. Da bi se napravila kranijalna proteza koja savršeno odgovara nedostajućem dijelu lobanje, koriste se tehnike računarske slike (kompjuterska tomografija ili magnetna rezonanca) u kombinaciji sa 3D modeliranjem zasnovanim na slikama i 3D printanjem [3]

many other derivatives have been used in the operating room [2]. Polymethyl methacrylate (PMMA) prostheses are produced intraoperatively and require preparation of the binary mixture as well as implant adjustments - molding at the time of surgery that causes an increase in operating time. In large and complex defects, intraoperative implant adjustments, especially molding irregular-shaped curvature by hands, may cause poor aesthetic results. PMMA has many advantages: no donor is required, it is not too expensive, it is lightweight, strong, inert, radiolucent, non-ferromagnetic and stable. The disadvantages are that it has low adherence to the surrounding tissue and it may cause tissue reactions. In order to make a cranial prosthesis which perfectly fis to missing part of the skull, computer imaging techniques (Computed Tomography or Magnetic Resonance Imaging) in combination with image based 3D modeling, and 3D printing are used [3]

2. PRIKAZ SLUČAJA Nakon teške kraniocerebralne povrede, dvadesettrogodišnjem pacijentu zaostao je veliki koštani defekt koji je obuhvatao cijelu desnu polovinu lobanje i protezao se na krov očne šupljine (Slika 1).

2. CASE REPORT After a severe craniocerebral injury, a twenty-three-year-old patient was left with a large bone defect that covered the entire right half of the skull and stretched to the roof of the eye cavity (Figure. 1)

Slika 1. Izgled lobanje pacijenta nakon teške kraniocerebralne povrede

Figure 1. The skull of the patient after severe craniocerebral injury


209

Pacijent je imao kako estetske tako i funkcionalne poteškoće. S obzirom na veličinu defekta, nije bilo moguće načiniti adekvatnu rekonstrukciju nedostajućeg dijela lobanje primjenom standardnih neurohirurških metoda. Trodimenzionalni model lobanje napravljen je koristeći CT snimke u DICOM formatu i softver za obradu medicinskih slika – Materialise Mimics 10.01 (Slika 2). Koristeći digitalne tehnike isijecanja i preslikavanja sa lijeve strane lobanje, konstruisan je 3D model implanta kojim se uspješno zatvorio defekt na desnoj strani modela lobanje (Slika 3). Digitalni model implanta izvezen je u STL formatu za potrebe 3D printanja. Izrada prototipa proteze od PLA (polilaktička kiselina) plastike iz STL fajla izvršena je na 3D printeru Ultimaker 2+ korištenjem FDM (modeliranje spajanjem nanošenih slojeva) tehnologije (Slika 4). Nakon što je proces 3D printanja, koji je trajao oko 20 sati, završen, izrađen je kalup za izradu implanta od zubarskog gipsa (Slika 5). Tokom dvosatne hirurške intervencije, PMMA implantat, koji je napravljen intraoperativno koristeći pripremljeni kalup, uspješno je postavljen na mjesto defekta.

The patient had both aesthetic and functional difficulties. Given the size of the defect, it was not possible to make an adequate reconstruction of the missing skull part using standard neurosurgical methods. Three-dimensional skull model was done using CT images in DICOM format and medical image processing software – Materialise Mimics 10.01 (Figure 2). Using digital cutting and mirroring techniques on the left side of the skull, a 3D model of the implant was constructed, which successfully closed the defect on the right side of the skull model (Figure 3). The digital implant model was exported to the STL format for 3D printing purposes. Ultimaker 2+ 3D printer was used to print out a prototype PLA (Polylactic acid) implant from the STL file using FDM (Fused Deposition Modeling) technology (Figure 4). After the 3D printing process, which lasted about 20 hours, was completed, a mold for the implant was created using the dental plaster (Figure 5). During a two-hour surgical intervention, the PMMA implant, which was made intraoperatively using the preformed mold, was successfully placed at the defect site.

Slika 2. Digitalna 3D rekonstrukcija lobanje pacijenta Figure 2. Digital 3D reconstruction of the patient’s skull


210

Nakon osam dana oporavka pacijent je otpušten kući potpuno zadovoljan postignutim rezultatima (Slika 6). Osim obnovljene estetike kranijalnog svoda pacijent je prestao imati glavobolje uzrokovane djelovanjem atmosferskog pritiska na moždano tkivo. Stanje pacijenta se prati već sedam mjeseci – dobro se osjeća i vratio se svojim svakodnevnim aktivnostima.

After eight days of the recovery, the patient was released home fully satisfied with the achieved results (Figure 6). In addition to the restored aesthetics of the cranial vault, the patient did not have headaches caused by atmospheric pressure on the brain tissue. The patient's condition has been monitored for seven months - he feels well and returned to his everyday activities.

Slika 3. Zatvaranje koštanog defekta lobanje implantom Figure 3. Closing the skull bone defect with the implant

Slika 4. 3D isprintani model implanta Figure 4. 3D printed implant model

Slika 5. Kalup za implant napravljen od zubarskog gipsa

Figure 5.Mold for the implant made from dental plaster


211

Slika 6. Uporedni prikaz izgleda pacijenta prije i nakon rekonstrukcije koštanog defekta lobanje Figure 6. Comparative presentation of the patient's appearance before and after the reconstruction of

the skull bone defect

3. ZAKLJUČAK Da bi se postigli odgovarajući estetski rezultati i izbjegle moguće komplikacije kod saniranja većih koštanih defekata lobanje, izrada proteze/implanta po mjeri pacijenta je od izuzetne važnosti. Na konkretnom primjeru, pokazano je da se, kombinirajući CT snimke, digitalnu rekonstrukciju modela, tehnologiju 3D printanja i zubarski gips kao materijal za izradu kalupa, mogu postići odlični rezultati kranioplastike.

3. CONCLUSION In order to achieve appropriate aesthetic results and avoid possible complications in the repair of the severe bone skull defects, customised prosthesis/implant production is of the great importance. In the case report, it was shown that, by combining CT scans, digital model reconstruction, 3D printing technology and dental plaster as a mold fabrication material, excellent cranioplastic results can be achieved.

4. REFERENCES [1] Dumbrigue HB, Arcuri MR, LaVelle WE, Ceynar KJ: Fabrication procedure for cranial prostheses. J Prosthet Dent. 1998 [2] Van Gool A.: Preformed polymethylmethacrilate cranioplasties. Report of 45 cases. J Maxillofac Surg. 1985 [3] Spahić D., Karač A.: Using magnetic resonance images tp create 3D models of bones for subsequent numerical analysis. Trends in the Development of Machinery and Associated Technology, 2009

Corresponding author: Denis Spahić University of Zenica Faculty of Politechnic Fakultetska 1, Zenica Email: [email protected]

INVITATION TO THE AUTHORS AND PARTICIPANTS Organizing Committee would like to invite all potential Organizing Committee would like to invite all potential authors and participants to submit abstracts (up to 100 words), not later than February 15th 2019. The official Conference languages are English, Bosnian, Serbian and Croatian. We remind authors that special section with presentations in English language will be organized at the conference. On line registration on www.quality.unze.ba

MAIN TOPICS CONFERENCE TOPICS The Research/Expert Conference will be performed as follows: plenary session (Key papers concerned global topics) and symposium (papers according to the conference topics). We would like to inform all the potential authors to prepare papers in the following topics: 1. QUALITY IN BUSSINES Quality management (Concept, Principles, Tools and Philosophies); System and Process Performance Measurements; Metrology; Quality of product and process; Quality in maintenance; Supply chain management; Environment protection quality; Quality Engineering; Quality Economics; Risk Control; Business Excellence 2. QUALITY IN EDUCATION Pedagogical standards and norms; Methods and procedures for control and monitoring of student achievements; Methods and procedures of educational staff quality control; Educational institutions self-evaluation; The Bologna process; Accreditation and certification of educational programs and institutions; Legislation in the education; ; Accreditation in Higher Education 3. QUALITY IN PUBLIC SECTOR Quality in public institutions; Quality in health institutions; Quality in community enterprises; Quality in Agriculture; Quality in Food Processing Industry; Aspect of Quality in Process Accesion BiH in EU; Quality in politics; The quality of the media; Quality in Tourism 4. STANDARDS REGULATION IN QUALITY International standards ISO 9000 - Quality Management System; International standards ISO 14000 - Environmental Management System; International standards ISO 45000 - Occupational Health and Safety; ISO 16949-Automotive quality management systems, ISO 22000-Food safety management system, ISO 27000-Information security management standards, ISO 26000-Social Responsibility, ISO

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UNIVERSITY OF ZENICA(Bosnia and Herzegovina)

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UNIVERSITY ERLANGEN NUREMBERG (Germany)

QUALITY ASSOCIATION ofBOSNIA and HERZEGOVINA

INSTITUT ZA PRIVREDNI INŽINJERING

B O S N I A & H E R ZE G O V I N A

UNIV

ERS I T Y O F ZEN IC A

UNI V

ERS IT A SS TU DI O R UM ZEN

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UNIVER SI TAS STUD IO RUM ZENIC

AEN

SIS

U NI

VERZI TETU ZENIC I

RESEARCH/EXPERT CONFERENCE WITH 11th

INTERNATIONAL PARTICIPATION

14 16 June 9 osnia and erzegovina- 201 , Neum, B H

UALITY91

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Proceedings indexed in:

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11th RESEARCH/EXPERT CONFERENCE WITH INTERNATIONAL

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Mašinstvo 4 (15), 213 – 226, (2018) E. Bešlagić: INFLUENCE OF CONTRACTION SHAPE ON THE…

213

UTICAJ OBLIKA KONVERGENTNE MLAZNICE NA KVALITET STRUJANJA U TESTNOJ SEKCIJI ZRAČNOG TUNELA

INFLUENCE OF CONTRACTION SHAPE ON THE FLOW QUALITY

IN WIND TUNNEL TEST SECTION

Ernad Bešlagić Mašinski fakultet, Univerzitet u Zenici Fakultetska 1, Zenica Ključne riječi: Konvergentna mlaznica zračnog tunela, kvalitet strujanja, računarska dinamika fluida Keywords: Wind tunnel contraction, the flow quality, computation fluid dynamics Paper received: 11.11.2018. Paper accepted: 21.12.2018.

Stručni rad REZIME Konvergentna mlaznica je dio zračnog tunela koji ima najveći uticaj na kvalitet strujanja zraka u testnoj sekciji. Omjer suženja, oblik poprečnog presjeka, dužina i oblik konture zida mlaznice su konstruktivni parametri koji, između ostalog, utiču na uniformnost strujanja, intenzitet turbulencije strujanja, ugao zakretanja toka, pojavu odvajanja toka te debljinu graničnog sloja toka fluida u testnoj sekciji. Zbog toga je veoma važno izabrati optimalnu kombinaciju navedenih konstruktivnih parametara mlaznice. U ovom radu je za kvadratni poprečni presjek izlaza mlaznice Ao=0,64 m2, vrijednost omjera suženja CR=4 i dužinu mlaznice L=1,88 m izvršena analiza pet različitih oblika konture zida mlaznice. Pomoću kompjuterskog koda Flow Simulation provedeno je 25 numeričkih simulacija te su analizirani dobiveni rezultati.

Professional paper

SUMMARY Contraction is a part of a wind tunnel that has the greatest impact on the air flow quality in the test section. The constriction ratio, the cross section shape, the length and wall shape are constructive parameters that influence the uniformity of the flow, the flow turbulence intensity, the flow rotation angularity, the appearance of the flow separation and the thickness of the fluid flow boundary layer in the test section. For this reason, it is very important to choose the optimal combination of the mentioned contraction design parameters. In this paper, an analysis of five different contours of the contraction wall was performed for the square outlet cross-section Ao=0.64 m2, the constriction ratio CR=4 and the contraction length L=1.88 m. With the computer code of Flow Simulation, 25 numerical simulations were performed and the obtained results were analyzed.

1. UVOD Razvoj široke lepeze proizvoda koji su u svom radu izloženi djelovanju aerodinamičkih sila bazirano je na teoretskim, eksperimentalnim i numeričkim metodama. Iako rezultati računarskih simulacija postaju sve tačniji i pouzdaniji, računarska dinamika fluida (CFD) još uvijek nije dostigla taj nivo da u potpunosti može eliminisati potrebu za eksperimentalnim podacima tokom razvoja spomenutih proizvoda. Ukoliko je to moguće, najuspješniji pristup razvoju nekog aerodinamičkog dizajna (novog ili postojećeg) temelji se na primjeni optimalne kombinacije rezultata dobivenih eksperimentalnim, teorijskim i računarskim putem. Osnovni alat eksperimentalne aerodinamike jeste zračni tunel. Adekvatna i produktivna

1. INTRODUCTION The development of a wide range of products that are exposed to aerodynamic forces in their work is based on theoretical, experimental and numerical methods. Although the results of computer simulations become more accurate and reliable, computer fluid dynamics has not yet reached that level to completely eliminate the need for experimental data during the development of the mentioned products. If possible, the most successful approach to the development of an aerodynamic design (new or existing) is based on the application of an optimal combination of results obtained by experimental, theoretical and computing method. The basic tool of experimental aerodynamics is a wind tunnel. Adequate and productive use of


214

upotreba zračnih tunela zahtijeva primjenu aerodinamičke teorije i računarskih metoda u toku razvoja i izrade zračnog tunela, u planiranju eksperimenata i interpretaciji dobivenih podataka. U ovom radu je pokazano kako se računarska dinamika fluida može iskoristiti kao alat prilikom razvoja jednog segmenta zračnog tunela. 2. OTVORENI ZRAČNI TUNEL Testiranja u zračnom tunelu su omogućila široku primjenu aerodinamike kao nauke u mnogim područjima tehnologije. Zračni tunel je fizički instrument, odnosno, postrojenje koje omogućuje da se u jednom od njegovih elemenata postigne ravnomjerna pravolinijska struja zraka određene brzine [2]. Na slici 1. prikazan je jednostavan otvoreni zračni tunel za male podzvučne brzine strujanja zraka.

wind tunnels requires the application of aerodynamic theory and computer methods during the development and construction of an air tunnel, in the planning of experiments and interpretation of the obtained data. This paper shows how computer fluid dynamics can be used as a tool in the development of one segment of the wind tunnel. 2. OPEN WIND TUNNEL Wind tunnel testing has enabled a wide application of aerodynamics as a science in many areas of technology. The wind tunnel is a physical instrument, a machine that allows one of its elements to achieve a uniform straight line air flow at particular velocity [2]. Figure 1. shows a simple open air tunnel for low subsonic air flow velocities.

Slika 1. Jednostavni otvoreni zračni tunel Figure 1. Simple open-circuit wind tunnel

Okolni zrak se pomoću ventilatora (5), koji se nalazi na kraju zračnog tunela, usisava u komoru za regulaciju i podešavanje strujanja (1). U njoj se strujanje zraka usmjerava u pravcu ose zračnog tunela i umiruju se veće nestabilnosti koje su prisutne u struji zraka. Nakon toga zrak ulazi u konvergentnu mlaznicu (2) čiji poprečni presjek se postepeno smanjuje što dovodi do ubrzavanja zraka. Prolaskom kroz najuži dio mlaznice zrak dostiže svoju maksimalnu brzinu strujanja i ulazi u testnu sekciju (3) koja ima konstantan poprečni presjek. U testnoj sekciji se nalazi predmet ispitivanja oko kojeg zrak ravnomjerno struji konstantnom brzinom. Iza testne sekcije nalazi se difuzor (4) u kojem dolazi do usporavanja zraka uslijed povećanja poprečnog presjeka. Promjenom broja obrtaja ventilatora postiže se željena brzina strujanja zraka u testnoj sekciji. Postoji veliki broj različitih vrsta, veličina i konstrukcija zračnih tunela. Ipak, njihove glavne karakteristike su jednake, a prisutne razlike su posljedica specijalnih zahtjeva koje

The ambient air is sucked in the control and the flow adjustment chamber (1) by the fan (5), located at the end of the wind tunnel. The flow of air is directed towards the axis of the air tunnel and the greater instabilities that are present in the air stream are calmed down in it. After that, the air enters the contraction (2), whose cross section gradually decreases, resulting in air acceleration. Passing through the contraction's narrowest part, the air reaches its maximum flow velocity and enters the test section (3) which has a constant cross-section. In the test section there is an object of testing around which the air flows uniformly at constant velocity. Behind the test section there is a diffuser (4) in which the air slows down due to cross-section increase. By changing the fan number of revolutions, the desired air velocity in the test section is achieved. There are many different types, sizes and designs of wind tunnels. However, their main characteristics are the same, and the present differences are the consequence of the special


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određeni zračni tunel mora ispuniti. Dizajn zračnog tunela treba prilagoditi tako da on zadovoljava specifične ciljeve istraživanja sa jedne, te raspoložive finansijske i prostorne resurse sa druge stane. Osnovni zahtjev koji mora ispuniti zračni tunel jeste obezbjeđenje ravnomjernog pravo-linijskog strujanja u testnoj sekciji. Strujanje mora biti uniformno i pravolinijsko u što je moguće većem dijelu poprečnog presjeka testne sekcije. Takva raspodjela brzine treba biti zadržana po skoro cijeloj dužini testne sekcije. Ispunjenje ovog zahtjeva se postiže adekvatnim oblikom i dimenzijama osnovnih dijelova zračnog tunela, pri čemu najveći uticaj imaju elementi koji se nalaze neposredno prije i poslije testne sekcije. 3. KONVERGENTNA MLAZNICA Konvergentna mlaznica koja se nalazi sa ulazne strane testne sekcije ima najveći uticaj na kvalitet strujanja u testnoj sekciji. Ubrzanje strujanja koje se događa u mlaznici utiče na uniformnost strujanja, intenzitet turbulencije, pojavu separacije i debljinu graničnog sloja. U zavisnosti od konkretnih zahtjeva koje mora ispuniti zračni tunel, vrijednosti navedenih karakteristika strujanja moraju biti u određenim granicama. 3.1. Konstrukcioni parametri mlaznice Konstrukcioni parametar koji najviše utiče na ispunjenje navedenih kriterija koje konvergentna mlaznica mora ispuniti jeste omjer suženja CR, koji se najčešće izražava kao odnos ulazne i izlazne površine. Pored njega, na kvalitet strujanja utiču oblik poprečnog presjeka, oblik konture zida i dužina mlaznice [3]. Dizajniranje konvergentne mlaznice svodi se na pronalaženje najoptimalnije kombinacije ova četiri nezavisna parametra. U većini slučajeva se a priori odrede omjer CR i oblik poprečnog presjeka, a nakon toga dužina mlaznice, te se proces dizajniranja svodi na jednoparametarski problem, odnosno, bira se najpovoljniji oblik konture zida za izabrane poprečne presjeke i dužinu mlaznice. 3.1.1. Omjer suženja CR Izlazni poprečni presjek konvergentne mlaznice Ae je velikim dijelom određen poprečnim presjekom testne sekcije. Ulazni poprečni presjek Ai se određuje na osnovu usvojenog omjera suženja CR=Ae/Ai. Prilikom izbora omjera suženja moraju se uzeti u obzir i prostorna i finansijska ograničenja.

requirements that a certain wind tunnel must achieve. The design of the wind tunnel should be adapted so that it meets the specific objectives of the research from the one, and the available financial and spatial resources on the other end. The basic requirement that the wind tunnel must achieve is to ensure a uniform straight line flow in the test section. Such kind of flow must be in as large as possible part of the cross section of the test section. Such a speed distribution should be retained in almost the entire length of the test section. Fulfilment of this requirement is achieved with the adequate shape and dimensions of the basic parts of the wind tunnel, with the greatest influence on the elements that are located immediately before and after the test section. 3. CONTRACTION The contraction located on the input side of the test section has the greatest influence on the flow quality in the test section. The flow acceleration provided in the nozzle affects the uniformity of the flow, the turbulence intensity, the appearance of separation and the thickness of the boundary layer. Depending on the specific requirements that the air tunnel must fulfill, the values of the specified flow characteristics must be within certain limits. 3.1. Contraction construction parameters The construction parameter that most affects the fulfilment of the specified criteria that the contraction must meet is the contraction ratio CR, which is the most often expressed as the ratio of the input and output surfaces. In addition to this, the shape of the cross-section, the wall shape and the length have influence on the flow quality [3]. The design of a contraction is targeted to finding the most optimal combination of these four independent parameters. In most cases, it is a priori to determine the ratio of the CR and the shape of the cross-section, followed by the length of the contraction, and the design process is targeted to a one-parameter problem, ie. the optimal wall shape. 3.1.1. The contraction ratio CR The output cross-section of the contraction Ae is largely determined by the cross-section of the test section. The input cross-section Ai is determined on the basis of the adopted constriction ratio CR=Ae/Ai. When selecting the constriction ratio, space and financial constraints must be taken into


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U savremenim zračnim tunelima omjer suženja se kreće u rasponu od 4 do 25, zavisno od vrste tunela [2]. Omjer suženja mlaznice određuje se u zavisnosti od tražene brzine u testnoj sekciji i od konstrukcijskih ograničenja. Za većinu malih, nisko brzinskih zračnih tunela prikladni su omjeri suženja od 6 do 10. To su tuneli sa površinom poprečnog presjeka testne sekcije manjom od 0,5 m2 i srednjom brzinom manjom od 40 m/s [3]. 3.1.2. Oblik poprečnog presjeka Osim omjera suženja, drugi parametar koji se mora odabrati a priori je oblik poprečnog presjeka. Tok u uglu mlaznice obično je podložniji separaciji uslijed vrlo malih brzina koje se javljaju u ovom području. Pored toga, poprečna i sekundarna strujanja također imaju tendenciju da se razvijaju u uglovima. Kako bi se izbjegli ti neželjeni uticaji, idealni oblik poprečnog presjeka suženja je kružni. Zbog toga je u početku većina mlaznica imala ili kružni ili osmougaoni poprečni presjek koji je bio pokušaj kompromisa između pravouglog i kružnog poprečnog presjeka. Naknadna istraživanja [5] su pokazala da za kvadratne ili pravokutne poprečne presjeke, u odsustvu odvajanja, uticaji kutnog toka ostaju lokalizirani te da se oblik poprečnog presjeka može odabrati tako da odgovara ostalim dijelovima tunela, prvenstveno testnoj sekciji. 3.1.3. Dužina konvergentne mlaznice Dizajn konvergentne mlaznice za dati omjer suženja i oblik poprečnog presjeka se svodi na određivanje adekvatne dužine i oblika konture zida mlaznice u cilju dobijanja uniformne i stabilne struje zraka na izlazu iz mlaznice i sprječavanja pojave razdvajanja toka. Također, bitno je postići minimalnu debljinu graničnog sloja na izlazu iz mlaznice što upućuje na to da se dužina mlaznice treba što je moguće više minimizirati. Kraća mlaznica je poželjna i sa aspekta smanjena prostora i troškova. Međutim, rizik pojave odvajanja graničnog sloja raste sa smanjivanjem dužine. Odvajanje graničnog sloja u mlaznici dovodi do pojave nejednakosti i nestabilnosti toka na izlazu, što dovodi do smanjenja efektivnog omjera suženja. Ta pojava se izbjegava dovoljnim povećanjem dužine mlaznice, pod uslovom adekvatnog oblika konture zida, tako da granični sloj ne raste previše u blizini izlaza. Dužina mlaznice L se najčešće izražava u odnosu na karakterističnu dimenziju ulaznog poprečnog presjeka - prečnik Di kod kružnog ili

consideration. In modern wind tunnels, the constriction ratio is between 4 and 25, depending on the type of tunnel [2]. The contraction ratio is determined depending on the required velocity in the test section and the design constraints. For most small, low-speed air tunnels, the appropriate ratio is between 6 and 10. These are tunnels with a cross-sectional area of the test section of less than 0.5 m2 and with an average velocity of less than 40 m/s [3]. 3.1.2. Cross-section shape In addition to the constriction ratio, the second parameter that must be selected a priori is a cross-sectional shape. The flow in the nozzle corner is usually more susceptible to separation due to very low velocities occurring in this area. In addition of this, transverse and secondary flows also have tendention to develop in corners. To avoid these unwanted effects, the ideal shape of the cross-section constriction is circular. For this reason, in the beginning, most nozzles had either a circular or octagonal cross section which was a compromise between a rectangular and circular cross-section. Subsequent studies [5] showed that for squared or rectangular cross sections, in the absence of separation, the angular flow effects remain localized and that the shape of the cross section can be selected to correspond to other parts of the tunnel, primarily to the test section. 3.1.3. Contraction length The design of a contraction for a given constriction ratio and a cross-section shape is targeted to determining the adequate length and wall shape in order to obtain a uniform and stable air flow at the outlet of the nozzle and to prevent the appearance of the flow separation. Also, it is important to achieve a minimum thickness of the boundary layer at the outlet, which suggests that the length should be minimized as much as possible. A shorter contraction is desirable from the aspect of reduced space and cost. However, the risk of separation of the boundary layer increases with length decreasing. Separation of the boundary layer in the nozzle leads to the inequality and instability of the outlet flow, which leads to a reduction in the effective contraction ratio. This phenomenon is avoided by a sufficient increase in the length of the nozzle, provided the appropriate wall shape in such way that the boundary layer does not grow too much near the exit. The length L is most often expressed in relation to the characteristic dimension of the inlet cross-


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visina Hi kod kvadratnog poprečnog presjeka. Taj odnos se najčešće kreće u granicama od 0,75 do 1,25. 3.1.4. Oblik konture zida mlaznice Kontura zida mlaznice se obično sastoji od dvije spojene krive linije. Svaka od njih ima svoj vrh na jednom od krajeva mlaznice. Prva kriva linija je konkavnog oblika i poželjno je da se taj dio produži što je više moguće kako bi se izbjeglo razdvajanje graničnog sloja od zida. Drugi dio krive ima konveksan oblik koji može zbog pozitivnog gradijenta pritiska uzrokovati razdvajanje toka u blizini testne sekcije. I za ovu pojavu rješenje je povećanje dužine mlaznice, što zbog prostornih i finansijskih ograničenja nije uvijek moguće. Zbog toga je neophodno odrediti optimalnu dužinu mlaznice. Ukoliko je dužina mlaznice ranije određena onda treba odrediti optimalan oblik konture zida mlaznice. Postoji veliki broj različitih oblika zida, od kružnih lukova, preko krivih linija trećeg ili četvrtog reda do Bézier-ovih krivih višeg reda. Kako je uticaj oblika zida mlaznice na kvalitet strujanja dosta kompleksan, neophodna je upotreba računarske dinamike fluida u cilju određivanja optimalnog omjera suženja, dužine i oblika zida mlaznice. U ovom radu je CFD analiza iskorištena za određivanje parametara strujanja na izlazu iz mlaznice za različite oblike konture zida i definisane ulazne i izlazne poprečne presjeke i dužinu mlaznice. 4. CAD MODEL MLAZNICE Poprečni presjek testne sekcije zračnog tunela, čija mlaznica se ispituje u ovom radu, je kvadrat sa stranicom dužine 0,8 m. To je ujedno i veličina izlaznog poprečnog presjeka mlaznice (He=0,8 m). Raspoloživi prostor i finansijska sredstva su imala dominantu ulogu kod određivanja omjera suženja i dužine mlaznice. Usvojen je omjer suženja CR=4 tako da je stranica ulaznog otvora Hi=1,6 m. Dužina mlaznice iznosi 1,88 m tako da se odnos između dužine mlaznice i karakteristične dužine ulaznog otvora (L/Hi=1,175) nalazi unutar preporučenih vrijednosti. 4.1. Parametrizacija oblika konture zida

mlaznice U prethodnom tekstu je navedeno da je oblik mlaznice određen sa velikim brojem različitih parametara. Usvajanjem osnovnih dimenzija mlaznica ostalo je samo da se definiše profil

section - the diameter Di at the circular or the height Hi at square cross-section. This ratio usually ranges from 0.75 to 1.25. 3.1.4. The contraction wall shape The nozzle wall contour usually consists of two connected curved lines. Each of them has its apex at one of the nozzle ends. The first curve has a concave shape and it is desirable that this part be extended as much as possible to avoid separating the boundary layer from the wall. The second curve has a convex shape which can, due to a positive pressure gradient, cause a separation of the flow near the test section. And for this phenomenon, the solution is to increase the length, which due to space and financial constraints is not always possible. It is therefore necessary to determine the optimum length. If the length is earlier determined, then the optimum wall shape should be determined. There are many different wall shapes, from circular arcs, through the curves of the third or fourth order to the Bézier's higher-order curves. Since the influence of the wall shape on the flow quality is rather complex, it is necessary to use computer fluid dynamics in order to determine the optimal constriction ratio, length and wall shape. In this paper, the CFD analysis was used to determine the flow parameters at the nozzle outlet for different wall contours and defined the inlet and outlet cross sections and the nozzle length. 4. CAD MODEL OF CONTRACTION The cross section of the air tunnel test section, whose contraction is examined in this paper, is a square with a side length of 0.8 m. It is also the size of the outlet cross-section of the nozzle (He=0,8 m). The available space and financial resources had a dominant role in determining the constriction ratio and the length of the nozzle. The CR = 4 ratio was accepted so that the side of the inlet opening is Hi=1,6 m. The contraction length is 1.88 m so that the ratio between the nozzle length and the characteristic length of the inlet opening (L/Hi=1,175) is within the recommended values. 4.1. Parameterization of the contraction wall

shape The preceding text it is stated that the shape of the nozzle is determined by a large number of different parameters. By accepting the basic dimensions of the nozzles, only the wall shape


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Slika 2. Kontura zida mlaznice koju čine dva spojena kružna luka Figure 2. Nozzle wall contour constructed of two matched arcs

zida mlaznice. Uvođenjem dodatnih relacija i pojednostavljenja oblik mlaznice se može učiniti zavisnim od samo jednog parametra. U našem slučaju usvojeno je da se profil zida mlaznice sastoji od konkavnog i konveksnog kružnog luka koji se spajaju u tački M (slika 2.). Između kružnih lukova je postavljena relacija tangentnosti tako da je prelazak sa jednog na drugi kružni luk neprimjetan. Također, vrhovi kružnih lukova se poklapaju sa krajevima mlaznice što osigurava fin prijelaz sa mlaznice na susjedne komponente zračnog tunela. Uvođenjem odnosa između z koordinate spojne tačke M i ukupne dužine mlaznice oblik krive profila zida mlaznice postaje zavisan samo od tog jednog parametra: pz=zM/L.

need to be defined. By introducing additional relationships and simplifying, the shape of the nozzle can be made dependent on only one parameter. In our case, it was accepted that the wall shape consists of a concave and a convex circular arc that meeting each other at point M (Figure 2.). A relationship of tangency is set between the circular arches in such way that the transition from one circular arc to other is invisible. Also, the circular arcs apexes coincide with the ends of the nozzle, which ensures a fine transition from the contraction to the adjacent components of the air tunnel. By introducing a relationship between the z coordinate of the joint point M and the total length, the contraction wall shape becomes dependent only on that one parameter (pz=zM/L).

Slika 3. 3D model konvergentne mlaznice

Figure 3. 3D model of contraction

5. NUMERIČKA SIMULACIJA STRU-JANJA ZRAKA KROZ MLAZNICU

5.1. SolidWork Flow Simulation Numeričke simulacije strujanja zraka kroz mlaznicu su izvršene pomoću kompjuterskog koda Flow Simulation koji je dio softverskog

5. NUMERICAL AIR FLOW SIMULA-TION THROUGH THE NOZZLE

5.1. SolidWorks Flow Simulation Numerical air flow simulations through the nozzle were computed using the computer code of Flow Simulation, which is part of the


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paketa SolidWorks Premium. Flow Simulation rješava Navier-Stokes-ove jednačine, koje predstavljaju primjenu zakona o održanju mase, momenta i energije na strujanje fluida. Te jednačine se dopunjavaju jednačinama stanja fluida koje opisuju ponašanje fluida, te empirijskim zavisnostima gustoće fluida, viskoznosti i toplotne provodljivosti od temperature. Neelastični ne-Newton-ovi fluidi razmatraju se uvođenjem zavisnosti njihove dinamičke viskoznosti o smicanju i temperaturi, dok se stišljivi fluidi razmatraju uvođenjem zavisnosti njihove gustoće od pritiska. Dati problem je konačno određen definisanjem njegove geometrije, te graničnih i početnih uslova. Flow Simulation može predvidjeti i laminarna i turbulentna strujanja. Laminarna strujanja javljaju se pri niskim vrijednostima Reynoldsovog broja, koji se definiše kao proizvod reprezentativnih vrijednosti brzine i dužine podijeljen kinematskom viskoznošću. Kada Reynolds-ov broj pređe određenu kritičnu vrijednost, protok postaje turbulentan, tj. parametri protoka se počinju nasumično mijenjati. Većina strujanja fluida u inženjerskoj praksi je turbulentna, tako da je Flow Simulation uglavnom razvijen kako bi se simulirala i proučavala turbulentna strujanja. Za predviđanje turbulentnih strujanja koriste se vremenski usrednjene Navier-Stokes-ove jednačine, gdje se uzimaju u obzir vremenski usrednjeni uticaji turbulencije na parametre strujanja, dok se drugi, tj. veliki, vremenski zavisni fenomeni direktno uzimaju u obzir. Kroz ovaj postupak, u jednačinama se pojavljuju dodatni izrazi, poznati kao Reynolds-ovi naponi, za koje se moraju obezbijediti dodatne informacije. Kako bi se zatvorio ovaj sistem jednačina, Flow Simulation koristi transportne jednačine za kinetičku energiju turbulencije i brzinu njene disipacije, tzv. k-� model [6]. Flow Simulation na osnovu 3D modela kreiranog u SolidWorksu automatski kreira pravougaonu računarsku mrežu u okviru računarske domene. Odgovarajuća računarska domena generiše se u obliku pravougaonog paralelopipeda koji sadrži model za 3D i 2D analizu. Njene granice su paralelne sa ravninama globalnog koordinatnog sistema. Tokom postupka kreiranja mreže, računarska domena se dijeli u jednake pravougaone ćelije oblika paralelopipeda i na taj način se formira

SolidWorks Premium software package. Flow Simulation solves the Navier-Stokes equations, which are formulations of mass, momentum and energy conservation laws for fluid flows. The equations are supplemented by fluid state equations defining the nature of the fluid, and by empirical dependencies of fluid density, viscosity and thermal conductivity on temperature. Inelastic non-Newtonian fluids are considered by introducing a dependency of their dynamic viscosity on flow shear rate and temperature, and compressible liquids are considered by introducing a dependency of their density on pressure. A particular problem is finally specified by the definition of its geometry, boundary and initial conditions. Flow Simulation is capable of predicting both laminar and turbulent flows. Laminar flows occur at low values of the Reynolds number, which is defined as the product of representative scales of velocity and length divided by the kinematic viscosity. When the Reynolds number exceeds a certain critical value, the flow becomes turbulent, i.e. flow parameters start to fluctuate randomly. Most of the fluid flows encountered in engineering practice are turbulent, so Flow Simulation was mainly developed to simulate and study turbulent flows. To predict turbulent flows, the Favre-averaged Navier-Stokes equations are used, where time-averaged effects of the flow turbulence on the flow parameters are considered, whereas the other, i.e. large-scale, time-dependent phenomena are taken into account directly. Through this procedure, extra terms known as the Reynolds stresses appear in the equations for which additional information must be provided. To close this system of equations, Flow Simulation employs transport equations for the turbulent kinetic energy and its dissipation rate, the so-called k-� model [6]. Flow Simulation considers the real model created in SolidWorks and automatically generates a rectangular computational mesh in the Computational Domain. The corresponding Computational Domain is generated in the form of a rectangular parallelepiped enclosing the model for both the 3D analysis and 2D analysis. Its boundaries are parallel to the Global Coordinate System planes. In the mesh generation process, the computational domain is divided into uniform rectangular parallelepiped-shaped cells, which form a so-called basic mesh. Then, using information about the model geometry, the specified


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tzv. osnovna mreža. Nakon toga, na osnovu geometrije modela, definisanih graničnih uslova i postavljenih ciljeva, Flow Simulation nastavlja proces kreiranja mreže putem brojnih dorada, odnosno, dijeljenja osnovnih mrežnih ćelija. Na taj način se postiže bolje predstavljanje područja koje ispunjavaju model i fluid. Ta tzv. početna mreža je u potpunosti definisana osnovnom mrežom i postavkama dorade mreže Svaka dorada mreže ima svoje kriterije i nivo. Kriteriji dorade definišu koje ćelije će se dijeliti, dok nivo dorade definiše najmanju veličinu do koje će se ćelije dijeliti. Ta najmanja veličina ćelija uvijek je definisana u odnosu na veličinu ćelije osnovne mreže, tako da je osnovna mreža od velike važnosti za konačnu računarsku mrežu. Flow Simulation nudi opciju dorade mreže tokom samih izračuna. Rezultatima prilagodljiva dorada mreže je proces dijeljenja ćelija računarske mreže u područjima gdje greške računanja (pogotovo lokalne greške uzrokovane skraćivanjem, odnosno, pojednostavljivanjem matematičkih procedura) mogu biti dosta velike te spajanjem ćelija u područjima gdje su te greške zanemarive [6].

boundary conditions and goals Flow Simulation further constructs the mesh by means of various refinements, i.e. splitting of the basic mesh cells into smaller cells, thus better representing the model and fluid regions. The mesh, which the calculation starts from, so-called initial mesh, is fully defined by the generated basic mesh and the refinement settings. Each refinement has its criterion and level. The refinement criterion denotes which cells have to be split, and the refinement level denotes the smallest size, which the cells can be split to. Regardless of the refinement considered, the smallest cell size is always defined with respect to the basic mesh cell size so the constructed basic mesh is of great importance for the resulting computational mesh. Flow Simulation offers the option of mesh refinement during the calculation itself. Solution-adaptive refinement of the computational mesh during the calculation is a process of splitting the computational mesh cells in areas where the calculation error (specifically, the local truncation error (LTE)) may be sufficiently large and merging of the computational mesh cells in areas where the calculation error is definitely small [6].

a) b)

Slika 4. Računarska domena (a) i položaj kontrolnih tačaka na izlaznom otvoru mlaznice (b) Figure 4. Computational domain (a) and the position of the control points at the nozzle outlet (b)

5.2. Postavke numeričke simulacije Prvo je napravljen okvirni plan eksperimenta. Planirano je da se za pet različitih brzina strujanja ispita pet različitih oblika konture zida mlaznice. Prilikom kreiranja 3D modela vođeno je računa da jedna dimenzija mlaznice upravlja oblikom konture mlaznice. Usvojeno je da se

5.2. Numerical simulation settings First of all, a general plan of the experiment is made. It is planned to examine five different wall shapes for five different flow rates. While creating a 3D model of the nozzle, it is considered that one dimension controls the shape of the contour of the nozzle. It was


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izvrši testiranje za pet različitih vrijednosti parametra pz: 0,2; 0,35; 0,5; 0,65 i 0,8 (slika 2.) za pet srednjih brzina vm na izlasku iz mlaznice: 4, 8, 12, 16 i 20 m/s. Mlaznica je simetričnog oblika te je računarska domena prilagođena tako da obuhvata samo jednu četvrtinu mlaznice (slika 4.a). Na taj način je znatno smanjeno vrijeme potrebno za proračune. Postavke mreže su postavljene tako da je u blizini zida mlaznice dobivena dovoljno sitna mreža koja će obezbijediti dobijanje pouzdanih preliminarnih rezultata na osnovu kojih će biti moguće donijeti odluku o tome koja oblik konture je najpovoljniji. Dobivena je mreža sa oko 750 hiljada ćelija. U cilju određivanja kvaliteta strujanja na izlazu iz mlaznice, na izlaznoj ravnini su postavljene kontrolne tačke u kojima su definisani ciljevi simulacije: ukupna brzina strujanja i njene tri komponente. Odabrane su tačke na horizontalnoj i vertikalnoj osi, te na dijagonali izlaznog poprečnog presjeka. Definisan je parametar položaja tih tačaka kao odnos x koordinate tačke i polovine ukupne širine izlaznog poprečnog presjeka: px=x/hi. Ukupno je odabrano 19 tačaka za sedam vrijednosti parametra px: 0; 0,1; 0,3; 0,5; 0,7; 0,9 i 1 (slika 4.b).

accepted to test five different values of the parameter p: 0,2; 0,35; 0,5; 0,65 and 0,8 (Figure 2.) for five average velocity values vm at the outlet of the nozzle: 4, 8, 12, 16 i 20 m/s. The contraction is symmetrical, and the computer domain is accepted in that way to cover only one-fourth of the nozzle (Figure 4.a). In this way, the time required for the calculations has been considerably reduced. Mesh settings have been set in way that a sufficiently small mesh is created near the wall of the nozzle, which will provide reliable preliminary results, based on which it will be possible to decide which form of contour is most favorable. A mesh with 750 thousand cells was obtained. In order to determine the flow quality at the exit, control points are defined at the output plane, in which the objectives of the simulation are defined: the total flow velocity and its three components. Points at the horizontal and vertical axes were selected and at the diagonal of the output cross-section. The position parameter of these points is defined as the ratio of the x coordinate of the point and half of the total width of the output cross-section: px = x/hi. A total of 19 points were selected for the seven values of the px parameter: 0; 0.1; 0.3; 0.5; 0.7; 0.9 and 1 (Figure 4.b).

Slika 5. Postavke What If Analysis Figure 5. What If Analysis settings

Kao granični uslovi definisani su protok na ulazu i atmosferski pritisak na izlazu. Ulazni protok je određen tako da na izlazu obezbijedi željene brzine strujanja. Pri tome je podijeljen sa četiri pošto je analizirano strujanje samo kroz jednu četvrtinu mlaznice. Preostale tri četvrtine mlaznice su uzete u obzir definisanjem uslova simetričnosti na ravninama front i top. Opcija Parametric Study je iskorištena za pravljenje jedne What If Analysis pomoću koje

The boundary conditions define flow at the input and atmospheric pressure at the exit. The inlet flow is determined in such way that at the output it provides the desired flow velocities. In that way, it is divided by four, since only one quarter of the nozzle is analyzed. The remaining three-quarters of the nozzle were taken into count by defining the conditions of symmetry on the front and top planes. The Parametric Study option was used to create one What If Analysis and it is used for a plan of


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je kreiran plan od 25 numeričkih eksperimenata. Parametri na osnovu kojeg je kreiran scenarij eksperimenta su bili granični uslov zapreminskog protoka na ulazu i geometrijski parametar oblika konture mlaznice (slika 5). Nakon toga je pokrenuta analiza i dobiveni su određeni rezultati. 6. ANALIZA DOBIJENIH REZULTATA Dobiveni rezultati su pokazali da je vrijednost brzine u horizontalnom i vertikalnom pravcu skoro identična, što se moglo i očekivati. Zbog toga ćemo analizirati samo raspored brine duž horizontalne ose. Na slici 6. prikazan je raspored z komponente brzine. To je komponenta koja je u pravcu ose konvergentne mlaznice. Prikazane su vrijednosti koje su dobivene u okviru eksperimenta broj 8 (D.P. 8). To je slučaj kada je ulazni zapreminski protok toliki da obezbjeđuje brzinu na izlazu 12 m/s, a parametar pz ima vrijednost 0,35. Brzina je prikazana na dva načina, pomoću kontura i izolinija. Kod prikaza brzina pomoću linija koje povezuju sve tačke u kojima je brzina ista, jasno se može vidjeti koliki je uticaj ugla kvadratnog poprečnog presjeka na raspored brzina. Potvrđeno je da taj uticaj nije toliko veliki i da je opravdano korištenje kvadratnog poprečnog presjeka. Na slici 7. prikazan je profil brzine za ovu tačku eksperimenta. Dobiveni profil brzine ima djelomično očekivani oblik, pošto brzina neznatno opada kako se približavamo centru mlaznice. Na slici 8. prikazani su 3D profili brzina za različite kombinacije ulaznih parametara. Pri tome nisu uzimane u obzir nulte brzine u tačkama koje se poklapaju sa zidom mlaznice.

25 numerical experiments creation. The parameters on the basis of which the experiment script was created were the boundary condition of the volume flow at the inlet and the geometric parameter of the contour shape of the nozzle (Figure 5). After that the analysis was performed and some results were obtained. 6. ANALYSIS OF OBTAINED RESULTS The obtained results showed that the velocity value in the horizontal and vertical directions is almost identical. And that could be expected. Therefore, we will analyze only the velocity spreading along the horizontal axis. Figure 6. shows the z component of velocity spreading. It is a component that is in the direction of the convergent nozzle axis. The values obtained under experiment No. 8 (D.P. 8) are displayed. This is the case where the input volume flow is such that it provides a velocity of 12 m/s at the output, and the parameter pz has a value of 0.35. Velocity is shown in two ways, using contours and isolines. When displaying velocities using lines that connect all the points in which the velocity has the same value, one can clearly see the effect of the angle of the square cross-section on the velocity spreading. It was confirmed that this effect is not so large and it is justified to use a square cross-section. Figure 7. shows the velocity profile for this experiment point. The obtained velocity profile has a partially expected shape, as the velocity slightly drops as we get closer to the center of the nozzle. Figure 8. shows 3D velocity profiles for different combinations of input parameters. Zero speeds were not taken into consideration at points that match the nozzle wall.

a) b)

Slika 6. Raspored z komponente brzine na izlazu iz mlaznice Figure 6. The z-component velocity contour at the nozzle output


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Slika 7. Profil z komponente brzine duž horizontalne ose na izlazu iz mlaznice (D.P. 8)

Figure 7. The z-component velocity profile along the horizontal axis at the nozzle output (D.P. 8)

Slika 8. 3D profil z komponente brzine duž horizontalne ose na izlazu iz mlaznice

Figure 8. The 3D z-component velocity profile along the horizontal axis at the nozzle output


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Urađene numeričke analize su stacionarne, odnosno, neovisne o vremenu tako da nije moguće odrediti uniformnost strujanja i intenzitet turbulencije. Procjena koji od analiziranih profila mlaznice je najprihvatljiviji izvršena je na osnovu srednjih brzina strujanja duž horizontalne ose na izlazu iz mlaznice. Iz analize je izuzeta tačka koja se nalazi na samom kraju jer je brzina u njoj jednaka nuli. Na slici 9. dat je grafički prikaz srednjih brzina za sve analizirane brzine. Odavde se vidi da su, prema ovom kriteriju, najprihvatljivije mlaznice kod kojih parametar oblika pz ima vrijednost 0,35 i 0,5.

The performed numerical analyzes are stationary, that means that they are independent of time so that it is not possible to determine the flow uniformity and the turbulence intensity. An estimate of which of the analyzed nozzle profiles is most acceptable is based on the average flow velocities along the horizontal axis at the outlet of the nozzle. The analysis excluding the point that is placed at the very end because the velocity at this point is zero. Figure 9. gives a graphical representation of average velocities for all analyzed velocities. From this it can be seen that, according to this criterion, the most acceptable nozzles in which the parameter of the form pz has a value of 0.35 and 0.5.

Slika 9. Srednje brzine strujanja za pet analiziranih vrijednosti brzina

Figure 9. Mid flow velocities for five analysed velocity values


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Na osnovu dobivenih vrijednosti tri komponente brzine i ukupne brzine u svim tačkama izlaznog poprečnog presjeka, moguće je odrediti ugao zakretanja toka. Ugao zakretanja toka je mjera ravnosti toka, odnosno, to je odnos između dvije poprečne komponente brzine i glavne komponente brzine. U ovom radu je ugao zakretanja toka računat kao ugao između vektora ukupne brzine i komponente brzine u pravcu ose mlaznice. U svakoj analiziranoj tački na horizontalnoj osi izlaznog poprečnog presjeka izračunat je ugao zakretanja za svih 25 provedenih numeričkih simulacija. Zatim su izračunate srednje vrijednosti uglova zakretanja toka duž horizontalne ose. Dobivene vrijednosti su prikazane grafički na slici 10. Može se vidjeti da na ugao zakretanja toka neznatno utiče povećanje brzine strujanja, dok ugao primjetno raste sa povećavanjem geometrijskog parametra pz.

On the basis of the obtained values of the three velocity components and the total velocity at all points of the output cross-section, it is possible to determine the flow angularity. The flow angularity is the measure of the straightness of the flow, i.e., the ratio between the two cross flow velocities and the streamwise velocity. In this paper, the angularity of flow rotation is calculated as the angle between the total velocity vector and the velocity component in the direction of the nozzle axis. In each of the analyzed points on the horizontal axis of the output cross-section, the flow angularity was calculated for all 25 numerical simulations that were performed. Then, the average values of the flow rotation angles along the horizontal axis are calculated. The obtained values are shown graphically in Figure 10. It can be seen that the angle of flow rotation is slightly affected by an increase in the flow velocity, while the angle is noticeably increasing with the increase of geometric parameter pz.

Slika 10. 3D prikaz vrijednosti ugla zakretanja toka

Figure 10. The 3D view of flow angularity

7. ZAKLJUČAK Konstrukcija konvergentne mlaznice je složen postupak pošto postoje četiri konstruktivna parametra koja u većoj ili manjoj mjeri utiču na kvalitet strujanja u testnoj komori zračnog tunela. U većini slučajeva se postupak pronalaska optimalne kombinacije navedena četiri parametra svede na analizu uticaja samo jednog parametra. Postoje više razloga za to, a najčešći su prostorna i finansijska ograničenja. U ovom radu je za kvadratni poprečni presjek izlaza mlaznice Ao=0,64 m2, vrijednost omjera suženja CR=4 i dužinu mlaznice L=1,88 m izvršena analiza pet različitih oblika konture zida

7. CONCLUSION The construction of a contraction is a complex process because there are four constructive parameters that greater or lesser influence the flow quality in the test section of the wind tunnel. In most cases, the process of finding an optimal combination of these four parameters are reduced to the analysis of the only one parameter impact. There are several reasons for this and the most common are space and financial constraints. In this paper, an analysis of five different contours of the nozzle wall was performed for the square cross-section of the nozzle outlet Ao=0.64 m2, the contruction ratio


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mlaznice. Kontura zida mlaznice se sastojala od dva kružna luka koja su spojeni u jednoj tački i između kojih je uspostavljena relacija tangentnosti. Pomoću kompjuterskog koda Flow Simulation provedeno je 25 numeričkih simulacija. Analizom dobivenih rezultata se može zaključiti da je za zadane konkretne vrijednosti tri geometrijska parametra najoptimalnija kontura zida mlaznice u kojoj se dva kružna luka spajaju na 35% ukupne dužine mlaznice. Varijanta sa spojnom tačkom na sredini mlaznice također nije loše rješenje, pogotovo što takav oblik mlaznice izgleda kao lakši za izradu. Kompjuterski kod Flow Simulation se pokazao kao dobar alat za donošenje preliminarnih odluka u ranoj fazi dizajna mlaznice. Iako su tokom numeričkih simulacija snimani i rezultati na vertikalnoj osi i duž dijagonale izlaznog poprečnog presjeka, u ovom radu su analizirane samo vrijednosti dobivene na horizontalnoj osi. Raspored brzina na izlazu iz mlaznice navodi na zaključak da je ta analiza dovoljna i da se na osnovu nje može zaključiti u kojem dijelu poprečnog presjeka je ostvaren zadovoljavajući kvalitet strujanja zraka.

CR=4 and the length L=1.88 m. The contraction wall shape consisted of two circular arcs connected at one point and between which the relation of tangency was set. Using the computer code of Flow Simulation, 25 numerical simulations were performed. By analyzing the obtained results, it can be concluded that, for the given concrete values of three geometric parameters, most optimal contour of the nozzle wall is that in which two circular arcs connected at the 35% of the total length of the nozzle. The variant with a connected point at the center of the nozzle is also not a bad solution, especially because this kind of contraction looks easier to produce. The Flow Simulation computer code proved to be a good tool for making preliminary decisions in the early stage of the design of the contraction. Although during numerical simulations the results on the vertical axis and along the diagonal of the output cross-section were recorded, only the values obtained on the horizontal axis were analyzed in this paper. The velocities distribution at the nozzle outlet leads to the conclusion that this analysis is sufficient and on this basis it can be concluded that in which section of the cross section the satisfactory air flow quality has been achieved.

8. REFERENCES [1] J.B. Barlow, W.H. Rae JR., A. Pope: Low

Speed Wind Tunnel Testing, 3rd edition, John Wiley and Sons, New York, 1999.

[2] S.M. Gorlin, I.I. Slezinger: Wind tunnels and their Instrumentation, Translated form Russian, Israel Program for Scientific Translations, Jerusalem 1969.

[3] J.H. Bell, R. D. Metha: Contraction Design for Small Low-Speed Wind Tunnels, NASACR- 182747, April 1988.

[4] T. Morel: Comprehensive Design of Axisymmetric Wind tunnel Contraction, Journal of Fluids Engineering, ASME, june 1975.

[5] R.D. Mehta: The Aerodynamic Design of Blower Tunnels with Wide-Angle Diffusers, Prog. Aerospace Sci., Vol. 18, No.1, 1977, pp. 54-120.

[6] SolidWorks Flow Simulation 2018 Technical Reference, Dassault Systems,

Coresponding author: Ernad Bešlagić University of Zenica, Faculty of Mechanical Engineering Email: [email protected] Phone: +387 61 61 20 61

Mašinstvo 4 (15), 227 – 236, (2018) M. Šišić: POSSIBILITY OF USING TEXTILE…

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MOGUĆNOST KORIŠTENJA TEKSTILNOG OTPADA KAO ENERGENTA U CEMENTNOJ INDUSTRIJI

POSSIBILITY OF USING TEXTILE WASTE AS AN ENERGY IN

CEMENT INDUSTRY

Muvedet Šišić University of Zenica Faculty of Mechanical Engineering Ključne riječi: tekstilni otpad, zbrinjavanje, cementara Keywords: textile waste, disposal, cementplant Paper received: 03.12.2018. Paper accepted: 24.12.2018.

Stručni rad REZIME Ostaci prirodnih i vještačkih materijala u pogonima tekstilne industrije predstavljaju poteškoću u tehnološkom postupku jer se radi o kontinuiranoj produkciji otpada i s tim u vezi i potrebi svakodnevnog zbrinjavanja. U Bosni i Hercegovini trenutno ne postoje pogoni za materijalno iskorištenje, recikliranje ili ponovnu upotrebu tekstilnog otpada. Deponije komunalnog otpada ne mogu biti mjesta njegovog krajnjeg zbrinjavanja. S druge strane tekstilni otpad sadrži potencijal za korištenje kao energenta a cementna industrija sa specifičnim prednostima u korištenju alternativnih goriva predstavlja optimalno rješenje zbrinjavanja otpada iz tekstilne industrije sa ekološkog i ekonomskog stanovišta

Professional paper

SUMMARY The remains of natural and artificial materials in the textile industry are a problem in the technological process because it is a continuous production of waste and related to the need for everyday care. In Bosnia and Herzegovina there are currently no facilities for the material utilization, recycling or reuse of textile waste. Municipal waste disposal cannot be the place for its final disposal. On the other hand, textile waste contains potential for use as an energy source and the cement industry with specific advantages in the use of alternative fuels is the optimal solution for the disposal of waste from the textile industry from the ecological and economic point of view

1. UVOD Kao nus product u tekstilnoj industriji nastaju značajne količine tekstilnog otpada u pogonima za krojenje kao ostaci rezanja . Dio otpadnih tekstilnih materijala većih dimenzija se nastoji ponovo iskoristiti za proizvodnju manjih predmeta od tekstila a neiskoristivi dio još uvijek najčešće završava na deponijama otpada a to bi trebao biti zadnji izbor. Poštivanjem načela reda prvenstva gospodarenja otpadom, koje propisuje Okvirna direktiva o otpadu te u skladu s razvojnom strategijom Europa 2020. uvođenjem kružnog, ekonomskog modela koji osigurava održivo gospodarenje resursima i produžavanje životnog vijeka materijala i proizvoda, može se spriječiti odlaganje velikih količina ovog otpada na odlagališta i njegovo bolje iskorištavanje. To podrazumijeva mjere poduzete prije negoli neka tvar, materijal ili proizvod postane otpad,

1. INTRODUCTION As a nus product in the textile industry, significant quantities of textile waste are generated in cutting plants as cutting residues. A part of the waste textile materials of larger dimensions is trying to reuse for the production of smaller items of textiles, and the useless part is still most often ending up in landfills, and this should be the final choice. Respecting the waste management priority principles laid down by the Waste Framework Directive and in line with the Europe 2020 development strategy, by introducing a circular, economic model that ensures sustainable resource management and prolong the lifetime of materials and products, the disposal of large quantities of this waste to landfills can be prevented and its better exploitation. This implies measures taken before any substance, material or product becomes waste,


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uključujući ponovnu upotrebu proizvoda ili produženje životnog vijeka istog te svesti isti na najmanju moguću mjeru. Starteška opredjeljenja u FBiH takođe idu u smjeru smanjenja količine otpada za finalno odlaganje / zbrinjavanje uz efikasnije korištenje resursa. Operativni ciljevi koji se, između ostalog odnose na iskorištavanje otpada u energetske svrhe : 7.2.6. Povećati udio otpada koji se reciklira odnosno podliježe povratu materijala i energije (R&R), uz istovremeno smanjenje količina preostalog otpada za odlaganje (% od ukupno adekvatno zbrinutog). S druge strane postoje nastojanja postrojenja sa značajnom potrošnjom fosilnih goriva da ista zamijene alternativnim gorivima kao što su različite vrste otpadnih materijala. Jedini postojeći korisnik alternativnih goriva u BiH je Fabrika cementa Lukavac, koja je 2012. godine pokrenula postupak uvođenja i upotrebe alternativnih goriva. Ista trenutno ima odobrenje za suspaljivanje alternativnih goriva do 30% od ukupne količine spaljenog goriva. Kao potencijalni budući korisnik RDF-a u Bosni i Hercegovini identifikovana je i Tvornica cementa Kakanj. Količine goriva iz otpada koje Tvornica cementa Kakanj ima mogućnost suspaliti su: - 2019. godine 22.164 tone, - 2020. godine 22.178 tona, - 2021. godine 22.193 tona. Elektroprivreda BiH u svom Dugoročnom planu razvoja također navodi interes za ispitivanje potencijalnih kapaciteta i mogućnosti korištenja RDF-a kao jeftinog goriva za proizvodnju električne i toplotne energije u kogenerativnim termoelektranama. Budući da su alternativna goriva energent kojim se već trguje na evropskom tržištu te da su pojedine evropske zemlje poput Njemačke, Austrije i Mađarske veliki uvoznici, realne su i mogućnosti za izvoz istog u zemlje EU. Uvoz alternativnih goriva u zemlje EU definiran je Baselskom konvencijom o nadzoru prekograničnog prometa opasnog otpada i njegovog odlaganja. Bazelsku konvenciju, BiH je ratificirala 2000. godine. 2. VRSTE ALTERNATIVNIH GORIVA S obzirom na dostupnost i karakteristike opredjeljujuće za korištenje kao energenta, za

including the reuse of the product or the prolongation of the lifetime of the product, and minimizing it to the minimum. Start-down commitments in the FBiH are also aimed at reducing the amount of waste for final disposal / disposal with more efficient use of resources. Operational objectives, which relate, inter alia, to the utilization of waste for energy purposes: 7.2.6. Increase the share of waste that is recycled or subject to material and energy recovery (R & D), while reducing the amount of residual waste to be disposed of (% of the total adequately disposed of). On the other hand, there are efforts of plants with significant fossil fuel consumption to replace them with alternative fuels such as different types of waste materials. The only existing user of alternative fuels in BiH is the Lukavac cement factory, which in 2012 started the process of introducing and using alternative fuels. It currently has the approval to suspend alternative fuels up to 30% of the total amount of burned fuel. As a potential future user of RDF in Bosnia and Herzegovina, the Cement Factory Kakanj has been identified as well. The amount of fuel from the waste that Kakanj cement factory has the possibility of suspending are: - In 2019, 22,164 tons, - In 2020, 22.178 tons, - In 2021, 22,193 tons. Elektroprivreda BiH in its Long-term Development Plan also cites an interest in examining the potential capacity and possibilities of using RDF as a cheap fuel for the production of electricity and heat in cogeneration thermal power plants. Since alternative fuels are already energy-traded on the European market, and that some European countries such as Germany, Austria and Hungary are big importers, the possibilities for exporting it to EU countries are realistic. Importing alternative fuels into EU countries is defined by the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and its Disposal. The Basel Convention was ratified in 2000 by BiH 2. TYPES OF ALTERNATIVE FUELS Given the availability and characteristics that are decisive for use as a fuel,


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ovu namjenu najčešće se koriste sljedeće vrste: GIO (RDF/SRF), otpadna guma i otpadna ulja. 2.1. GIO- gorivo iz otpada Gorivo iz otpada kao energent se dobiva obradom otpada, tj. usitnjavanjem papira, kartona, plastike, drveta, tekstila, guma i ostataka visoke energetske vrijednosti iz uljnih filtera. U Bosni i Hercegovini trenutno nema pogona za proizvodnju RDF-a i sve količine potrebne za pogone koji koriste iste kao alternativno gorivo se uvoze. Visokokvalitetni sekundarni energent definisane hemijske i energetske kvalitete. Primjeri iz evropske cementne industrije pokazuju da procenat zamjene fosilnih goriva dominantno gorivom iz otpada ponegdje prelazi i 70 %. Da bi se klasificiralo kao gorivo iz otpada, takvo gorivo mora biti obrađeno, homogeno i sastavom odgovarati određenim kriterijima kao što je vlažnost, kalorijka vrijednost, sadržaj pepela, teških metala i sl. Proizvodi se u kontrolisanim uslovima i prema strogim kriterijima kontrole kvaliteta. SRF Solid Recovered Fuel definira se u saglasnosti sa CEN/TC 343 kao podkategorija RDF-a sa uspostavljenim zahtjevima kao što su: - velike homogene količine, - pouzdani kvalitativni standardi, - dugoročna dostupnost, - pogodnost za skladištenje i transport, - ekonomska efikasnost. Nabrojane karakteristike može da zadovolji tehnološki otpad iz tekstilne industrije u uvjetima kontrolisanog sakupljanja i adekvatne pripreme. Na Slici 1 je prikazan izgled obrađenog GIO.

the following types are commonly used for this purpose: RDF / SRF, waste tire and waste oils. 2.1. RDF - Refuze Derived Fuel Waste fuel as energy source is obtained by treating waste, i. by crushing paper, cardboard, plastic, wood, textiles, tires and residues of high energy values from oil filters. In Bosnia and Herzegovina, there are currently no plants for the production of RDFs, and all the quantities needed for drives that use the same as alternative fuel are imported. High quality secondary energy defined by chemical and energy quality. Examples from the European cement industry show that the percentage of fossil fuel substitution dominated by waste is somewhere in excess of 70%. To be classified as waste fuel, such a fuel must be processed, homogeneous, and in compliance with certain criteria such as humidity, calorific value, ash content, heavy metals, and the like. It is produced under controlled conditions and according to strict quality control criteria. SRF Solid Recovered Fuel is defined in accordance with CEN / TC 343 as an RDF sub-category with established requirements such as: - large homogeneous quantities - reliable quality standards - long-term availability - convenience for storage and transport - economic efficiency The listed characteristics can satisfy technological waste from the textile industry under conditions of controlled collection and adequate preparation. Figure 1 shows the look of the processed RDF.

Slika 1. Gorivo iz otpada

Figure 1. Refuze derived fue


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2.2. Otpadana guma U EU više od 2,5 miliona tona guma se proizvede godišnje, a gotovo 40% tih guma se iskoristi na ovaj način. Različiti rezultati testova pokazuju da TDF nema negativan uticaj na emisije, odnosno korištenje TDF-a ne izaziva nedozvoljena prekoračenja graničnih vrijednosti za emisiju U usporedbi s ugljem, sadržaj NOx i emisije HCl uglavnom opadaju ili ostaju iste uz upotrebu gume. Emisije organskih tvari, dioksina i furana su također primjetno niže. Na Slici 2 su prikazane osnovne vrste otpadne gume: otpadna automobilska i guma od kablova

2.2. Waste tire In the EU more than 2.5 million tons of tires are produced annually, and almost 40% of these tires are used in this way. Different test results show that TDF does not have a negative impact on emissions, or the use of TDF does not cause unacceptable overshoots of emission limit values. In comparison with coal, NOx content and HCl emissions generally fall or remain the same with the use of rubber. Emissions of organic substances, dioxins and furans are also noticeably lower. In Figure 2, the basic types of waste tires are shown: waste cartire and rubber tires.

Slika 2. Otpadna guma

Figure 2. Waste tire 2.3. Otpadno ulje Otpadno ulje je svako iskorišteno mineralno i sintetičko mazivo, industrijsko i/ili termičko ulje koje više nije za upotrebu kojoj je prvobitno bilo namijenjeno. Razlikujemo više kategorija otpadnih ulja prema stepenu onečišćenja od kojih je kao energent najprimjenjivija kategorija otpadnih ulja mineralnog, sintetičkog i biljnog porijekla sa sadržajem halogena iznad 0,2% i ispod 0,5% i ukupnim polikloriranim bi- i terfenilima iznad 20 mg/kg i ispod 30 mg/kg. Ova se ulja mogu koristiti kao gorivo u energetskim i proizvodnim postrojenjima instalirane snage uređaja veće ili jednake 3 MW ili u pećima za proizvodnju klinkera. Na Slici 3 je prikazano otpadno ulje.

2.3. Waste oil Waste oil is any used mineral and synthetic lubricant, industrial and / or thermal oil that is no longer for the intended use. We distinguish several categories of waste oils according to the degree of pollution, of which the category of waste oils of mineral, synthetic and plant oils with the content of halogens is above 0.2% and below 0.5% and the total polychlorinated bi- and terphenyls above 20 mg / kg are the most applicable category of waste oils. below 30 mg / kg. These oils can be used as fuel in energy and production plants with an installed power of more than 3 MW or in clinker production furnaces. Figure 3 shows waste oil.


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Slika 3. otpadno ulje Figure 3. Waste oil

3. KARAKTERISTIKE TEKSTILNOG OTPADA Za određivanje karakteristika tekstilnog otpada za primjer je uzet tekstilni otpad iz industrije automobilskih presvlaka koji u sastavu ima prirodne materijale kao što je pamuk ali i vještačke kože i poliuretan. Ovaj otpad je predstavljen Slikom 4.

3. TEXTILE WASTE CHARACTERISTICS For the determination of the characteristics of textile waste, for example, textile waste from the automotive leather industry, consisting of natural materials such as cotton but also artificial leather and polyurethane, is taken. This waste is presented in Figure 4.

Slika 4. Tekstilni otpad Figure 4. Textile waste

Karakteristike koje je Cementara Kakanj kao jedna od potencijalnih korisnika alternativnih goriva postavila kao uslove predstavljeni su sljedećom tabelom.

The characteristics that Cementara Kakanj as one of the potential users of alternative fuels has set as conditions are presented in the following table.

Tabela 1. Potrebne karakteristike alt. goriva

Fizički parametri Jedinica Vrijednost

Veličina čestice mm < 30 Sadržaj pepela % mas. < 15 Sadržaj vlage % mas. < 15 Neto kalorična vrijednost

kJ/kg >20

Hemijski parametri Jedinica Vrijednost Kadmij mg/kg < 6 Živa mg/kg < 1 Hlor % mas. < 1

Table 1. Required characteristics alt. fuel

Physical parameters Unit Value

Particle size mm < 30 Ash content % mas. < 15 Moisture content % mas. < 15 Net calorific value kJ/kg >20 Chemical param. Unit Value Cadmium mg/kg < 6 Quicksilver mg/kg < 1 Chlorine % mas. < 1


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Karakteristike tekstilnog otpada iz industrije automobilskih presvlaka prema standaru CEN/TS 15359:2OO5 E predstavljene su u Tabeli 2.

Characteristics of textile waste from the car CEN / TS 15359: 2OO5 E are presented in industry industry according to the standard Table 2.

Tabela 2. Karakteristike tekstilnog otpada Table 2. Characteristics of textile waste

4. MOGUĆNOSTI KORIŠTENJA

TEKSTILNOG OTPADA KAO ENERGENTA

4. POSSIBILITIES OF USING TEXTILE WASTE AS ENERGY

Osnovne prednosti korištenja tekstilog otpada kao energenta su sljedeće: • ekološki ispravno rješenje zbrinjavanja ove

vrste otpada kao balasta u tehnološkim postupcima u tekstilnoj industriji,

• ušteda prirodnih resursa korištenjnem ove vrste otpada umjesto fosilnih goriva,

• umanjenje količina otpada za odlaganje na deponije,

• dostupnost otpada kao resursa s obzirom na ukupne količine otpada u svim granama tekstilne indusrije,

• smanjenje štetnih emisija i ublažavanje negativnih uticaja na okoliš u odnosu na sagorjevanje fosilnih goriva.

• ušteda prostora na deponijama otpada. Korištenje tekstilnog otpada kao alternativnog energenta u rotacionim pećima u cementnoj industriji i drugim pogonima u kojima je moguće vršiti njegovo spaljivanje ili suspaljivanje predstavlja ekološki ispravno

The basic advantages of using textile waste as a fuel are as follows: • an environmentally sound solution for the

disposal of this type of waste as a ballast in technological processes in the textile industry,

• saving natural resources using this type of waste instead of fossil fuels,

• reduction of quantities of waste for disposal to landfills,

• the availability of waste as a resource with respect to the total quantities of waste in all branches of the textile industry,

• reduction of harmful emissions and mitigation of negative impacts on the environment in relation to the burning of fossil fuels.

• saving space on landfills The use of textile waste as an alternative fuel in rotary kilns in the cement industry and other plants where it is possible to burn or suspend it represents an environmentally sound solution.

Physical parameters Unit Value Ash content % mas. 4,16 Moisture content % mas. 0,62 Net calorific value kJ/kg 23,038 Chemical param. Jedinica Vrijednost Cadmium mg/kg 0,28 Chromium mg/kg 5,26 Cobalt mg/kg 0,25 Copper mg/kg 12,07 Lead mg/kg 26,79 Manganese mg/kg 24,27 Nickel mg/kg 8,64 Zinc mg/kg 39,48 Iron mg/kg 321,96 Quicksilver mg/kg < 0,01 Chlorine % mas. 1,39 Heavy metals mg/kg 439,01

Fizički parametri Jedinica Vrijednost Sadržaj pepela % mas. 4,16 Sadržaj vlage % mas. 0,62 Neto kalorična vrijednost

kJ/kg 23,038

Hemijski parametri Jedinica Vrijednost Kadmij mg/kg 0,28 Krom mg/kg 5,26 Kobalt mg/kg 0,25 Bakar mg/kg 12,07 Olovo mg/kg 26,79 Mangan mg/kg 24,27 Nikal mg/kg 8,64 Cink mg/kg 39,48 Željezo mg/kg 321,96 Živa mg/kg < 0,01 Hlor % mas. 1,39 Teški metali mg/kg 439,01


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rješenje i dio je preporuka u najboljim raspoloživim tehnikama za ovu oblast.

and is part of the recommendations in the best available techniques for this field.

Izazovi korištenja tekstilnog otpada kao energenta su sljedeći: • manja toplotna moć u odnosu na fosilna

goriva, • potrebna je primarna obrada tekstilnog

otpada prije spaljivanja ili suspaljivanja u skladu sa zahtjevima postrajenja u kome će biti upotrebljen,

• kontrola sastava otpada zbog bilansa zagađujućih komponenti u otpadnim dimnim plinovima,

• prilagođavanje energetskog postrojenja uvjetima upotrebe otpada kao goriva.

Sva alternativna goriva pored toga što imaju manju toplotnu moć od primarnih fosilnih goriva moraju biti prilagođena za doziranje i moraju biti kontrolisanog sastava kako bi se izbjegle oscilacije u razvijenoj temperaturi sagorjevanja. Tehnološki otpad iz tekstilne industrije može imati dodatnu poteškoću ukoliko u svom sastavu ima prirodnu ili vještačku kožu. Ovi materijali sadrže hlor (Cl) koji sa sobom nosi određene rizike. Tokom sagorijevanja, svi materijali koji sadrže Cl ponašaju se na sličan način. Sa porastom temperature, organske komponente počinju se razlagati oslobađajući Cl, a na višim temperaturama hloridne soli počinju isparavati. Tokom procesa sagorijevanja nastaju gasovi koji u svom sastavu sadrže Cl, pri čemu su hlorovodonični (HCl) i hlorni Cl2) gas dominanti. Čim nastane Cl2 dolazi do njegove reakcije sa vodenom iz produkata sagorijevanja i nastaje hlorovodonična kiselina (HCl). Pri nižim temperaturama, poput onih na površini izmjenjivača toplote i cijevima kotla reakcijase odvija u suprotnom smjeru, dakle iz HCl-a nastaje reakcije Cl2, zaslužan za koroziju materijala. Da bi se sprijčila proizvodnja ovih toksičnih i korozivnih supstanci, HCl iz dimnih plinova se mora otkloniti putem kontrolnih procesa unutar jednog WTE postrojenja (postrojenja koje pretvara otpad uenergiju)

The challenges of using textile waste as a fuel are as follows: • lower thermal power compared to fossil

fuels, • the primary treatment of textile waste prior

to incineration or incineration is in accordance with the requirements of the installation in which it will be used,

• control of waste composition due to the balance of pollutant components in waste flue gases,

• adaptation of the energy plant to the conditions of use of waste as fuel.

All alternative fuels, in addition to having lower thermal power than primary fossil fuels, must be adapted for dosing and must be controlled to avoid oscillations in the developed combustion temperature. Technological waste from the textile industry can have additional difficulties if it has natural or artificial leather. These materials contain chlorine (Cl) which carries certain risks with it. During combustion, all Cl-containing materials behave in a similar manner. With the rise in temperature, the organic components begin to be interpreted as releasing Cl, and at higher temperatures the chloride salt begins to evaporate. During the combustion process there are gases containing Cl in their composition, where the hydrochloric (HCl) and chlorine Cl2) gas are dominant. As soon as Cl2 forms, its reaction with aqueous from the products of combustion results in hydrochloric acid (HCl). At lower temperatures, such as those on the surface of the heat exchanger and the boiler tubes, the reaction takes place in the opposite direction, hence from HCl, reactions of Cl2 are caused, corrosive to the material. In order to prevent the production of these toxic and corrosive substances, HCl from flue gases must be eliminated through control processes within a single WTE plant (plants that convert waste into energy)


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5. PRIMARNA OBRADA TEKSTILNOG OTPADA Standardi korištenja alternativnih goriva u cementarama zahtijevaju usitnjavanje otpada na max. 3 cm i bez trodimenzionalnih komada, Ovaj uslov je potrebno ispuniti zbog specifičnog načina dozioranja u rotacionu peć. Za ovu svrhu koristi se sjeckalica za otpad. Ovaj tip mašine ima veliki moment obrtanja a sastoji se od dva vratila za sjeckanje koji se obrću u suprotnom smjeru. Usljed velikog momenta obrtanja na ovaj način je moguće efikasno usitniti na potrebnu granulaciju tekstilni otpad različitog porijekla i sastava. Rotaciona sjeckalica kao glavni dio jednog takvog uređaja za usitnjavanmjne tekstilnog otpada predstavljena je na slici 5.

5. PRIMARY PROCESSING OF TEXTILE WASTE The standards for the use of alternative fuels in cement plants require the shredding of waste at max. 3 cm and without three-dimensional pieces, This condition must be met due to the specific way of dosing in the rotary kiln. For this purpose, a waste cutter is used. This type of machine has a high torque and consists of two shafts that rotate in the opposite direction. Due to the high turning speed in this way, it is possible to effectively crush the necessary granulation textile waste of different origin and composition. Rotary chip as the main part of such a device for crushed textile waste is presented in Figure 5.

Slika 5. Rotaciona sjeckalica

Figure 5. Rotary cutter

Operacijom siječenja tekstilnog otpada dobijemo material predstavljen na Slici 6 koji se nakon operacije usitnjavanja može balirati zbog efikasnijeg transporta do pogona cementare.

By treating textile waste we obtain the material presented in Figure 6 which can be baled after the smelting operation due to more efficient transport to the cement plant.

Slika 6. Usitnjeni tekstilni otpadFigure 6. Cut textile Waste


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Kabast i lagan tekstilni otpad ukoliko nije baliranjem pripremljen za transport značajno uvećava troškove transporta bez obzira da li radi o neusitnjenom ili usitnjenom otpadu, Na slici 7 je prikazan baliran tekstilni otpad (neusitnjen i usitnmjen)

Cabbage and light textile waste, if not prepared for transport, is substantially increasing transport costs, regardless of whether it is inadequate or crushed waste, Figure 7 shows baled textile waste (untreated and crushed)

Slika7. Baliran tekstilni otpad Figure 7. Baled textile waste

Osnovna shema primarne obrade tekstilnog otpada je predstavljen shemom na slici 8.

The basic scheme of primary processing of textile waste is presented by the scheme in Figure 8

Slika 8. Shema obrade tekstilnog otpada

Troškovi primarne obrade tekstilnog otpada prema prethodnoj shemi obuhvataju sljedeće troškove: • troškovi sakupljanja (postavljanje posuda ,

odlaganje i/ili baliranje tekstilnog otpada), • transport tekstilnog otpada do reciklažnog

centra gdje se tekstilni otpad istovara,

Figure 8.Scheme for processing of textile waste The costs of primary processing of textile waste according to the previous scheme include the following costs: • collection costs (placement of containers,

disposal and / or baling of textile waste), • Transportation of textile waste to a

recycling center where textile waste is unloaded,


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• usitnjavanje tekstilnog otpada, • utovar i transport usitnjenog tekstilnog

otpada do pogona za spaljivanje- cementara

• cutting of textile waste, • loading and transport of textile waste to the

incinerator-cement plant 5. ZAKLJUČAK

5. CONCLUSION

Upotreba otpadnih materijala kao energenta ima stratešku ulogu u integralnom upravljanju otpadom na principima održivog razvoja, To znači održivo upravljanje otpadom u smislu korištenja kao energenta uz pridržavanje potrebnih mjera na prihvatljivim ekološkim, ekonomskim i socijalnim osnovama kroz: • smanjenje udjela fosilnih goriva tj. uštedu

prirodnih resursa ( nafte, plina i uglja), • smanjenje štetnih emisija u zrak, vodu i tlo,

tj. ublažavanje negativnih uticaja na okoliš.

S druge strane radi se o zahtjevnoj organizaciji primarne obrade ovog otpada kako bi se zadovoljili standardi pogona u kojima se može iskoristiti njegov energetski potencijal. U integralnom sistemu upravljanja ovom vrstom otpada pored proizvođaća koji na ovaj način rješavaju problem zbrinjavanja otpada i pogona koji ga koriste kao jeftiniji energent, svoj interes moraju naći i kompanije koje se bave primarnom obradom otpada.

The use of waste materials as a fuel has a strategic role in integrated waste management on the principles of sustainable development. This means sustainable waste management in terms of use as a fuel, while adhering to the necessary measures on acceptable ecological, economic and social bases through: • reduction of the share of fossil fuels, ie

saving natural resources (oil, gas and coal), • reduction of harmful emissions into air,

water and soil, i.e. mitigation of negative environmental impacts.

On the other hand, there is a demanding organization of the primary processing of this waste in order to meet the standards of the plants in which its energy potential can be used. In the integrated management system for this type of waste, in addition to producers who in this way solve the problem of waste disposal and facilities that use it as a cheaper energy source, companies that deal with primary waste treatment also have an interest.

6. LITERATURA - REFERENCES [1] Bajtarević A.: Cement factory and

sustainable development, 5th International Scientific Conference Environmental and Material Flow Management, Zenica, 2015

[2] Enova, Analiza iskustava u proizvodnji i korištenju RDF-a u jugoistočnoj Evropi, Sarajevo, septembar 2016.

[3] Bajtarević A.: Otpadne gume kao alternativno gorivo u cementnoj industriji, Međunarodna konferencija o upravljanju opasnim i neopasnim otpadnom u regiji, Zenica, 2010.

[4] Studija o istraživanju mogućnosti korištenja alternativnih goriva u tvornici cementa Kakanj, Mašinski fakultet, Univerzitet u Zenici, Zenica, novembar 2016.

Coresponding author: Muvedet Šišić University of Zenica Faculty of Mechanical Engineering Email: [email protected] Phone: +387 61 470 627

Mašinstvo 4 (15), 237 – 245, (2018) N.Zaimović-Uzunović et all: 3D PRINTING ADDITIVE…

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IZRADA MODELA ADITIVNIM POSTUPKOM 3D PRINTANJA I DIMENZIONALNA PROVJERA NA CMM

3D PRINTING ADDITIVE PROCEDURE MODEL CREATION AND

DIMENSIONAL CHECK USING CMM

N Zaimovic-Uzunović, J Kačmarčik, K Varda, S Lemeš, D Spahić University of Zenica, Faculty of Mechanical Engineering, Fakultetska 1, Zenica Ključne riječi: 3D printanje, aditivne tehnologije, CMM, CNC mjerenje, brzi prototipi Keywords: 3D printing, additive technologies, CMM, CNC measurement, rapid prototyping Paper received: 09.10.2018. Paper accepted: 03.12.2018.

Stručni rad REZIME 3D printanje je tehnologija koja se sve više koristi u mnogim inženjerskim poljima i edukaciji. Ova tehnologija se prvenstveno koristi za brzo kreiranje prototipova i alata. U ovom radu je prikazana geometrijska tačnost FDM (modeliranje taložnim stapanjem) 3D printanja. Za proces dimenzionalnog ispitivanja, kreiran je 3D model, koji sadrži karakteristične geometrijske oblike i dimenzije, koje je poslužila kao referenca za mjerenje na koordinatnoj mjernoj mašini. CAD model je kreiran u softveru SolidWorks, model je printan na Ultimaker 2+ 3D printeru a mjerenje je vršeno na Zeiss Contura G2 koordinatnoj mjernoj mašini.

Professional paper

SUMMARY 3D printing is a technology that is increasingly used in many engineering fields and education. This technology is primarily used in rapid prototyping and rapid tooling. In this paper the geometrical accuracy of FDM (Fused Deposition Modelling) 3D printing is presented. For the dimensional test process, a 3D model which contains the characteristic geometrical shapes and dimensions that were used as a reference for measuring on the coordinate measurement machine, has been created. The CAD model was created in SolidWorks software, the model was printed on the Ultimaker 2+ 3D printer and the measurement has been proceeded on the Zeiss Contura G2 coordinate measuring machine

1. UVOD 3D printanje je aditivni proizvodni proces koji kreira dio direktno iz CAD modela, dodavajući sloj po sloj materijala jedan na drugi. Postoje različite komercijalne verzije printera, gdje je FDM (modeliranje taložnim stapanjem) najjeftinija verzija na tržištu. Postoje mnoga polja primjene 3D printera, uključujući brzu proizvodnju prototipova, dizajna dijelova, medicinu, edukaciju, arhitekturu i umjetnost.[1] Geometrijske karakteristike nekog dijela (tolerancije) su jedan od najvažnijih segmenata u procesu dizajna proizvoda. Koordinatna mjerna mašina je jedan od najboljih alata za dimenzionalno mjerenje. U polju prototajpinga gdje se 3D printeri najviše koriste, također su izraženi određeni geometrijski zahtjevi i postoji potreba za sve većom tačnošću izrade prototipa. Zbog prethodno navedenog razloga, 3D printanje se sve više koristi u naučnim i industrijskim studijama u svrhu povećavanja tačnosti printanja.

1. INTRODUCTION 3-D Printing is an additive manufacturing process that creates parts directly from CAD model, by adding layer by layer of material. There are different technologies commercially available, where Fused Deposition Modelling (FDM) is the cheapest one on the market. There are many fields of 3D printing application, including: rapid manufacturing and prototyping, product design, medicine, education, architecture and art. [1] Geometrical product specifications (tolerances) are very important part of product design process. Coordinate measuring machine is one of the ultimate tools for dimensional measurement. In the prototyping field where 3D printers are most used, certain geometrical requirements are expected and there is a need for ever greater prototype accuracy. Due to the foregoing reason, 3D printing is increasingly used in scientific and industrial studies in purpose of print accuracy increase.


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U ovom radu je pomoću CMM-a ispitana tačnost printanja konvencionalnog 3D printera Ultimaker 2+ na modelu složene geometrije.[2] Ovo ispitivanje ima i edukativnu svrhu, jer je ovo ispitivanje korišteno za izradu određenih završnih radova na Mašinskom fakultetu.

In this paper, CMM examines the accuracy of conventional 3D Ultimaker 2+ printer on a complex geometry model.[2] This examination also has educational purpose as this test was used to produce specific final papers at the Faculty of Mechanical Engineering.

ULTIMAKER 2+ 3D PRINTER I TEHNOLOGIJA KORIŠTENJA PRI ISPITIVANJU Ultimaker 2+ je široko rasprostranjen komercijalni 3D printer i korišten je za printanje referentnog modela. U tabeli 1 su prikazane specifikacije ovog modela printera kao i primjenjene opcije (označene oznakom *) koje su se koristile u ovom konkretnom slučaju (Slika 1).[3] Postoji više aditivinih materijala 3D printanja a u ovom konkretnom slučaju je korištena PLA (polilaktidna kiselina). PLA (polilaktidna kiselina) je biorazgradivi termoplastični poliester. Ovaj materijal se dobija iz obnovljivih izvora, odnosno iz kukuruznog škroba, i iz posebne vrste krompira koji se uzgaja u Aziji. PLA je zadnjih nekoliko godina postao sve prisutniji materijal zbog svojih karakteristika, prvensteno jer su modeli sjajniji i ne krive se kao modeli napravljeni od ABS-a.

2. ULTIMAKER 2+ 3D PRINTER AND TECHNOLOGY USED IN INVESTIGATION Ultimaker 2+ is a widely used commercial 3D printer and it is used for the reference model printing. Table 1 shows the specifications of this printer as well as the applied settings (marked with *) used in this particular case (Figure 1).[3] There are several additional materials for 3D printing, and in this particular case, PLA (polylactic acid) is used. PLA (polylactic acid) is a biodegradable thermoplastic polyester. This material is obtained from renewable sources that is from corn glass and from a special type of potato that is grown in Asia. PLA has become more and more present in the last few years due to its characteristics, primarily because the models are glossier and do not bend as models made of ABS.

Slika 1. Ultimaker 2+ 3D printer Figure 1. Ultimaker 2+ 3D printer

3. REFERENTNI MODEL I PRIPREMA ZA PRINTANJE U svrhu kontrole tačnosti printanja ispitivanog 3D printera, dizajniran je originalni referentni dio koristeći komercijalni CAD softver SolidWorks. CAD model je kreiran na osnovu tehničke dokumentacije detaljnih dimenzija i tolerancija (Slika 2).[3]

3. BENCHMARK PART AND 3D PRINTING PREPARATION For purpose of controlling the printing accuracy of investigated 3D printer an original benchmark part is designed using commercial CAD software Solidworks. CAD model is designed based on technical documentation which contains detailed dimensions and tolerances (Figure 2).[3]


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Table 1. 3D printer’s technical specifications and applied settings Tabela 1. Tehničke specifikacije 3D printera i primjenjene postavke (*)

Ultimaker 2+ 3D printer Specifications/Karakteristike Print technology/ Tehnologija printanja

Fused Deposition Modeling (FDM)/ Modeliranje taložnim stapanjem

Build volume/ Radna povrština 223x223x205 mm

Nozzle diameter/ Promjer brizgalice 0.25, 0.40* , 0.60, 0.80 mm

Layer Resolution/ Popunjenost sloja

20 to 600 μm, (200 μm)*

Materials/ Materijali

Open filament system, PLA*/ Pogodan za mnoga fibrilna vlakna

Filament diameter/ Promjer vlakna 2.85 mm

Print head/ Glava za printanje

One nozzle/ Jedna mlaznica

Slika 2. Tehnička dokumentacija referentnog modela

Figure 2. Technical documentation of benchmark model Dizajn se sastoji od više ravnina, koje sadrže cilindre različitih promjera, kao i konusnu rupu, žlijeb i kanal (Slika 3). Namjera je da dizajn posjeduje takve osobine da omogući kontrolu tačnosti različitih geometrijskih karakteristika kao što su veličina, forma, orjentacija i lokacija, odnosno geometrijskih specifikacija proizvoda, a koje bi mogle biti zahtjevi tolerancija 3D printanog dijela u određenim aplikacijama.[4]

Na osnovu CAD modela, koristeći Ultimaker Cura softver, model je pripremljen za printanje. Ovaj program predstavlja poveznicu između CAD modela, 3D printera i materijala. Za ovaj rad korištena je verzija softvera Ultimaker Cura 3.1.0, u koji je ubačen STL format prethodno napravljenog modela (Slika 4).[5]

The design contains multiple planes, which contain cylinders of different diameters, as well as coned hole, shaft and channel (Figure 3). The intention of the design is to have features on the part that provide possibility of controlling accuracy of different geometrical characteristics like size, form, orientation and location, i.e. geometrical product specification, which could be tolerance requirements for the 3D printed part in some practical application.[4]

Figure 4 shows the software environment in which the necessary parameters can be set, such as injection speed, resolution, layer thickness, material, fill, position from which the print starts, support structures and many other parameters.[5]


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Slika 3. Benchmark part CAD model

Figure 3. CAD model referentnog dijela

Slika 4. Ultimaker Cura softver za pripremu printanja

Figure 4. Ultimaker Cura software for printing preparation Na slici 4 je prikazano okruženje softvera u kome se mogu podesiti potrebni parametri, kao što su brzina brizganja, rezolucija, debljina sloja, materijal, popunjenost, pozicija iz koje počinje print, potporne strukture i mnogi drugi parametri. Nakon ubacivanja odgovarajućeg materijala u printer, G koda (instrukcija za printenje) sa modelom i parametrima, nakon 13 sati printanja, dobijen je vjerodostojan realni dio (Slika 5).[6]

Figure 4 shows the software environment in which the necessary parameters can be set, such as injection speed, resolution, layer thickness, material, fill, position from which the print starts, support structures and many other parameters. After inserting the appropriate material into the printer and G code (printing instructions) with the model and parameters, after 13 hours of printing, a reliable realistic part was obtained (Figure 5).[6]

Slika 5. Odgovarajući realni printani dio Figure 5. Reliable realistic printed part


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4. CMM MJERENJE Referentni model je mjeren na koordinatnoj mjernoj mašini Zeiss Contura G2 (opsega mjerenja: 700x1000x600 mm, mjerene nesigurnosti na osnovu ISO 10360-2: MPE_E=(1,8+L/350) μm, MPE_P=1,8 μm) opremljenom sa ZEIS VAST XT skenirajućom sondom i Calypso 4.8 softverom za mjeriteljstvo.[7] Plan mjerenja na CMM softveru je napravljen CAD programiranjem koristeći importovani CAD model. Nakon importovanja modela, bitno je definisati koordinatni sistem, domen unutar kojeg se kreće mjerna sonda i izvršiti mjerenje tri referentne ravnine na modelu.[8] Usklađivanje koordinatnog sistema radnog komada sa koordinatnim sistemom mašine vrši se ručnim skeniranjem ravnina 1, 2 i 3. Nakon poravnanja radnog komada, mjerenje svih definisanih dijelova se vrši CMM skeniranjem u jednom ciklusu mjerenja u CNC režimu rada. Strategije mjerenja za površinske karakteristike definišu se sa ručno kreiranim poligonom linija, imajući u vidu odgovarajuću površinsku pokrivenost; Karakteristike cilindra su definisane sa jednim ili dva kruga, ravnomjerno raspoređena. Algoritmi generisanja su zasnovani na principu najmanjih kvadrata i ta (Gausova) metoda se koristi u CMM mjerenjima (Slika 6).

4. CMM MEASUREMENT The benchmark part is measured on Coordinate measuring machine Zeiss Contura G2 (measurement range: 700x1000x600 mm, measurement uncertainty according to ISO 10360-2: MPE_E=(1,8+L/350) μm, MPE_P=1,8 μm) equipped with ZEIS VAST XT scanning probe and Calypso 4.8 measurement software.[7] The measurement plan in CMM software is made by CAD programming, using imported 3D model. After importing the model, it is necessary to define coordinate system, domain of measurement probe movement and measure three referent planes on the model.[8] Alignment of the work piece coordinate system in the machine coordinate system is done by manual probing of the planes 1, 2 and 3. After the work piece alignment, measurement of all defined features is performed by CMM scanning in one measurement cycle in CNC mode. Measurement strategies for plane features are defined with polylines, manually created, aiming for appropriate surface coverage; the cylinder features measurement strategies are defined with one or two circles, uniformly distributed. Fitting algorithms based on the principle of the least squares (Gaussian) method are used in CMM measurement (Figure 6).

Slika 6. Importovanje modela i početne postavke mjerenja

Figure 6. Import of the model and basic applied measurement settings Kreiranje strategija mjerenja podrazumijeva definisanje kretanja sonde i mjerenja određene površine modela. Definisane su 32 mjerne strategije za 14 ravnih i 18 cilindričnih površina (Slika 7). Za ravne površine definisane su konture kretanja nepravilnog oblika, gdje se mjerilo 600 tačaka pri brzini od 5 mm/s. Za cilindrične površine mjerilo se 200 tačaka pri brzini od 5 mm/s. Za otvore većeg prečnika definisane su dvije kružnice mjerenja, a za otvore manjeg

prečnika definisana je jedna kružnica mjerenja.[9]

Creating measurement strategies involves defining the probe movement and measuring the specific surface of the model. 32 measurement strategies were defined for 14 flat and 18 cylindrical surfaces (Figure 7). For flat surfaces, contours of irregular shaped movement are defined, where the measured number of points is 600 at a speed of 5 mm/s. For cylindrical surfaces, 200 points were measured at a


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speed of 5 mm/s. For larger holes, two measuring circles are defined, and one circle of measurement is defined for smaller diameter holes. [9]

Šezdeset različitih mjernih karakteristika dijela definisane su u CMM planu mjerenja za kontrolu tačnosti printanja na referentnom dijelu. Karakteristike u CMM softveru se koriste za definisanje geometrijskih dimenzija i tolerancija kontrolisanih dijelova i mogući rezultat CNC mjernog programa. Karakteristike su grupisane u šest grupa, a to su: ravnost, okomitost, ugao, paralelnost, cilindričnost i prečnik cilindra.[10]

Sixty different part measurement characteristics are defined in CMM measurement plan for controlling printing accuracy on the benchmark part. The characteristics in CMM software are used for definition of controlled work piece geometrical dimensions and tolerances and are possible output of a CNC measurement program. Part features are used for definition, and features measurement results for calculation of characteristics measurement results. The characteristics are grouped in six groups, and those are: flatness, perpendicularity, angularity, parallelism, cylindricity and diameter cylinder.[10]

Slika 7. Definisane ravne i cilindrične površine modela

Figure 7. Defined flat and cylindrical model planes 5. REZULTATI MJERENJA Izmjereni rezultati za sve karakteristike dijela printanog na Ultimaker 2+ 3D printeru su dati u tabeli 2. U tabeli su prikazane nominalne i izmjerene vrijednosti, kao i odstupanja kod prethodno navedenih karakteristika od interesa. Odstupanja pri mjerenju ravnosti površina ne prelaze 0,15mm, a u nekim slučajevima su vrijednosti ispod 0,1mm. Odstupanja za mjerenje okomitosti, ugla i paralelnosti ne prelaze 0,35mm. Vrijednosti cilindričnosti su unutar 0,8mm odstupanja. Bitno je naglasiti da su izmjerene vrijednosti promjera cilindara u svim slučajevima manje od nominalne vrijednosti i odstupanja pri mjerenju ne iznose više od 0,5mm. Maksimalno odstupanje posmatrajući sva mjerenja je 0,789mm, a minimalno 0,017mm.

5. MEASUREMENT RESULTS The measured results for all the characteristics of the printed part on the Ultimaker 2+ 3D printer are given in Table 2. The table shows the nominal and measured values, as well as the deviations of the above mentioned characteristics of interest. Deviations for flatness measurement do not exceed 0.15mm, and in some cases values are below 0.1mm. Deviations for perpendicularity measurement, angle and parallelism do not exceed 0,35mm. The cylindrical values are within the 0.8mm deviation. It is important to note that the measured cylinder diameter values are in all cases less than the nominal values and the deviations in the measurement are not greater than 0.5mm. The maximum deviation considering all measurements is 0,789 mm and minimum is 0,017 mm.


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Značajna činjenica koja je primjećena prilikom obrade rezultata je ta da su kod mjerenja cilindričnosti na datom modelu, značajne razlike u odstupanju kod onih cilindara koji se nalaze na gornjoj strani dijela u odnosu na one koji se nalaze na bočnim stranama. Maksimalno odstupanje cilindričnosti izmjerene na gornjoj strani dijela je 0,119mm a na bočnoj strani 0,789mm. Pretpostavlja se da je ovo posljedica karakteristike tehnologije izrade modela, gdje se u obzir trebaju uzeti činjenice da se materijal termički obrađuje i da je prilično porozan, a da kao posljedicu slijeganja materijala daje devijacije na bočnim stranama i ta činjenica bi trebala biti razmatrana u nekim budućim istraživanjima.

A significant fact observed in the results obtained is that when measuring the cylinders on a given model, significant differences in deviation is between those cylinders located on the upper side of the part and those on the sides. The maximum cylindrical deviation measured on the upper side of the part is 0.119 mm and on the sides is 0.789 mm. It is assumed that this is a consequence of the printing technology characteristics, where it should be considered the fact that the material is thermally treated and material is quite porous. Deviation on the part sides is consequence of the leakage of the material and this fact should be investigated in some future studies.

Tabela 2. Rezultati mjerenja

Table 2. Measurement results RAVNOST/FLATNESS

Pozicija/Position Izmjerena vrijednost/ Evaluated value (mm)

Nominalna vrijednost/

Nominal value (mm)

Odstupanje/ Deviation (mm)

Flatness 1 0.1206 ― 0.1206 Flatness 2 0.10892 ― 0.10892 Flatness 3 0.13937 ― 0.13937 Flatness 4 0.10413 ― 0.10413 Flatness 5 0.08288 ― 0.08288 Flatness 6 0.13399 ― 0.13399 Flatness 7 0.11733 ― 0.11733 Flatness 8 0.12164 ― 0.12164 Flatness 9 0.09883 ― 0.09883 Flatness 10 0.10858 ― 0.10858 Flatness 11 0.13033 ― 0.13033 Flatness 12 0.04002 ― 0.04002 Flatness 13 0.01737 ― 0.01737 Flatness 14 0.03073 ― 0.03073

OKOMITOST, UGAO I PARALENOST/ PERPENDICULARITY, ANGULARITY AND PARALLELISM

Perpendicularity 1 0.17821 ― 0.17821 Perpendicularity 2 0.14803 ― 0.14803 Perpendicularity 3 0.10213 ― 0.10213 Perpendicularity 4 0.18491 ― 0.18491 Perpendicularity 5 0.328 ― 0.328 Perpendicularity 6 0.11676 ― 0.11676 Angularity 1 0.09063 ― 0.09063 Angularity 2 0.15933 ― 0.15933 Parallelism 1 0.12626 ― 0.12626 Parallelism 2 0.21044 ― 0.21044


244

CILINDRIČNOST/CYLINDRICITY Cylindricity 1 0.11599 ― 0.11599 Cylindricity 2 0.10172 ― 0.10172 Cylindricity 3 0.11153 ― 0.11153 Cylindricity 4 0.11924 ― 0.11924 Cylindricity 5 0.44483 ― 0.44483 Cylindricity 6 0.27296 ― 0.27296 Cylindricity 7 0.25013 ― 0.25013 Cylindricity 8 0.27827 ― 0.27827 Cylindricity 9 0.13131 ― 0.13131 Cylindricity 11 0.30086 ― 0.30086 Cylindricity 12 0.33606 ― 0.33606 Cylindricity 13 0.20137 ― 0.20137 Cylindricity 14 0.34087 ― 0.34087 Cylindricity 15 0.14739 ― 0.14739 Cylindricity 16 0.14004 ― 0.14004 Cylindricity 17 0.10077 ― 0.10077 Cylindricity 18 0.78927 ― 0.78927

PREČNIK CILINDRA/DIAMETER CYLINDER Diameter Cylinder 1 29.78794 30 -0.21206 Diameter Cylinder 7 11.76409 12 -0.23591 Diameter Cylinder 8 19.7386 20 -0.2614 Diameter Cylinder 18 14.57327 15 -0.42673 Diameter Cylinder 10 11.79975 12 -0.20025 Diameter Cylinder 11 11.81108 12 -0.18892 Diameter Cylinder 12 11.87925 12 -0.12075 Diameter Cylinder 13 11.87039 12 -0.12961 Diameter Cylinder 14 5.81512 6 -0.18488 Diameter Cylinder 15 5.79232 6 -0.20768 Diameter Cylinder 16 5.83786 6 -0.16214 Diameter Cylinder 17 5.84552 6 -0.15448 Diameter Cylinder 3 11.85945 12 -0.14055 Diameter Cylinder 9 11.77889 12 -0.22111 Diameter Cylinder 2 11.9046 12 -0.0954 Diameter Cylinder 4 11.79275 12 -0.20725 Diameter Cylinder 5 29.68299 30 -0.31701 Diameter Cylinder 6 14.73846 15 -0.26154

8. LITERATURA - REFERENCES

[1] D.Godec, M.Šercer : Značaj aditivnih postupaka proizvodnje tvorevina u suvremenom razvoju i proizvodnji, FSB, Zagreb, 2013.;

[2] Fahad M, Hopkinson N 2012 A new benchmarking part for evaluating the accuracy and repeatability of Additive

Manufacturing (AM) processes, 2nd International Conference on Mechanical, Production and Automobile Engineering (ICMPAE'2012), Singapore, April 28-29;

[3] Solidworks manual, Dassault systemes, 2013.;

[4] Lemu HG, Kurtovic S 2011, 3D printing for rapid manufacturing: Study of


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dimensional and geometrical accuracy, InIFIP International Conference on Advances in Production Management Systems, Berlin, Sep 26, pp. 470-479;

[5] ULTIMAKER, Ultimaker 2+, https://ultimaker.com/en/products/ultimaker-2-plus, (accesed on March 13th 2018);

[6] A. Topčić, E. Cerjaković: Izrada prototipa, Tuzla, 2014.;

[7] ZEISS, ZEISS CONTURA: The Reference Machine in the Compact Class, https://www.zeiss.com/metrology/products/systems/bridge-type-cmms/contura.html, (accesed on March 12th 2018);

[8] Hocken RJ, Pereira PH (Eds.) 2016 Coordinate measuring machines and systems, CRC Press;

[9] Carl Zeiss 3D Metrology Services GmbH, Training manual Calypso 4.8, February 2009, Germany;

[10] Kačmarčik J, Spahić D, Varda K, Porča E., Zaimović-Uzunović N, 2018 An investigation of geometrical accuracy of desktop 3D printers using CMM, The 10th Internatonal Conference KOD 2018, Novi Sad, Serbia;

[11] Dimitrov D, Van Wijck W, Schreve K, De Beer N 2006, Investigating the achievable accuracy of three dimensional printing, Rapid Prototyping Journal 12(1):42-52;

Coresponding author: Kenan Varda University of Zenica, Faculty of Mechanical Engineering Email: [email protected] Phone: +387 61 85 37 46

Mašinstvo 4(15), 246 – 246, (2018) INFORMACIJE

246

ODRŽAN SEMINAR „USPJEŠNOST ODRŽAVANJA“

U privrednoj komori ZDK, 13. decembra 2018. godine održan je stručni seminar „Uspješnost održavanja“.

Teme seminara su bile:

- Održavanje kao funkcija i podsistem poslovnog sistema, potrebe upravljanja na osnovu činjenica, metode, predavač je bio prof. emeritus Safet Brdarević, UNZE

- Indeksne metode mjerenja uspješnosti održavanja, predavač je bio prof. dr. Sabahudin Jašarević, Politehnički fakultet UNZE

- Metode mjerenja uspješnosti održavanja po ISO standardu, predavač je bila mr. sc. Edina Aganović, BH Telecom d.d. Direkcija Zenica

- Višeparametarske metode mjerenja uspješnosti održavanja prof. emeritus dr. Safet Brdarević, UNZE

Seminaru je prisustvovalo 28 učesnika i to 50% iz privrede, 35% iz visokoškolskih institucija i 15% iz naučnih institucija. Kandidati su dobili uvjerenje da su odslušali seminar, što i m može poslužiti kao referenca u razvoju karijere. Organizatori seminara su bili Mašinski fakultet Zenica, Centar za menadžment, kvalitet i razvoj, Društvo održavalaca u BiH i Privredna komora ZDK.

Vođa projekta

Prof. emeritus dr. Safet Brdarević

Mašinstvo 4 (15), 247 – 251, (2018) J. Schwelberger, et all: RECYCLING OF FERROUS …

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RECYCLING OF FERROUS BY-PRODUCTS IN IRON AND STEEL PLANTS

Jörg Schwelberger, Chrisitan Brunner, Alexander Fleischanderl, Zijad Mandara PRIMETALS Technologies Austria GmbH, A joint venture of Siemens, Mitsubishi Heavy Industries and Partners, Turmstrasse 44, 4031 Linz, Austria Keywords: Recycling of By-Products, Cold Briquetting, Midrex, DRI Paper received: 11.11.2018. Paper accepted: 21.12.2018.

Conference paper SUMMARY

Due to rising energy prices and stringent environmental regulations, energy efficiency, resource saving and climate protection are becoming more important than ever. Primetals Technologies ECO Solutions offers a wide range of services and technologies to increase energy efficiency, reduce the environmental impact of steel production plants and to ensure efficient water and by-product management Primetals Technologies ECO Solutions provides processes and solutions along the entire iron and steel production chains, which meet the strictest emission regulations and also help producers achieve substantial cost savings. In response to these ecological and economic challenges, Primetals Technologies offers energy-efficient solutions and services along the entire process chain, with a clear objective: saving resources, creating value. The optimized consumption of energy and raw materials, the application of advanced technological processes and the maximum application of recycling solutions lead to major energy savings, reduced emissions, improved water and by-prooduct management. Saving resources • Minimized emissions • Minimized use of raw materials • Minimized energy consumption • Optimized by-product recycling Creating value • Reduction of conversion costs • Increase performance • Improve quality

1. INTRODUCTION Significant amounts of by-product fines are produced and collected in steel plants at all steps of iron & steelmaking. It can be assumed that per ton of steel produced around 60 -150 kg of particulate by-product is generated. Considering that these by-products have an average iron content of >50%, this is 3 up to 7,5% of the total steel production. Primetals Technologies has developed several recycling technologies for treating particulate by-products. Cold briquetting is one of the favorable solutions to transform fine material into recyclable agglomerates. 2. RECYCLING OF FINES – COLD

BRIQUETTING Recycling of only a part of the by-product stream to the sinter plant is very common. In many cases the addition of mainly unconditioned by-products may be possible, in some cases with a negative impact on the plant operation, such as increase generation of fines and reduction of productivity, and leaving still a large amount of by-products unused.

In order to include most or all of the generated by-products, cold briquetting of various dusts and sludges allows integrated recycling within existing primary production units. After pre-treatment of the residues, including drying, screening and mixing, binders are added and following the mixture is briquetted using roller-type presses. The selection of the binder system is dependent on desired metallurgical route for the respective recycling. In Figure 2 a block diagram of a cold briquetting process including pre-treatment of the waste material is shown. In the first step of the cold briquetting process the wet by-products are dried. Then the dried materials as well as other dusts are mixed while adding the binders. Afterwards the material is directly fed to a briquetting press. In a final step the product briquettes are screened and then conveyed to the curing and storage yard. Approximately 10% fines are internally recycled after the screening. Final product screening is done just before loading to the trucks.


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Figure 1. Typical by-product fines generation in an integrated steel mill

Figure 2. Cold briquetting process – Reference ILVA Taranto

The reference plant at ILVA Taranto was designed as 2-line briquetting arrangement for a yearly production of around 240,000 tons. The briquettes were foreseen to be recycled to the LD converter (BOF) and blast furnace (BF) up to certain defined amount.

LD approx. 4 t per heat (approx. 8 kg briquettes/tsteel) BF approx. 1% of burden

A combination of molasses and hydrated lime is used as binding agent. Following input materials are treated in this briquetting plant: • Converter fine sludge 30% • Converter coarse sludge 10%

• BF sludge 10% • Mill scale sludge 25% • Sec. LD-dust 5% • Dust catcher dust (BF) 10% • Separation iron fines 10% Briquettes with a high iron content and high basicity can be charged directly into LD converter (BOF), replacing cooling scrap or ore. Briquettes rich in carbon but with limited alkali and zinc contents can be charged into the blast furnace.


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Figure 3a and 3b: Product briquette Figure 4. Briquetting plant, ILVA Italy The main benefits of this system are: • Less raw materials utilization due to

recycling of by-products (ore, scrap, coke) and therefore reduced operating costs

• Minimization of landfilling costs and volume

• CO2 reduction • Sinter saving up to 5% (BF) • Short payback period

Similar to the example of recycling of fines in an integrated plant described above, the recycling of fines in an DRI based plants can be applied using cold briquetting technology. In DRI based steel mills there is normally no agglomeration plant such as the sinter plant available which offers the possibility to recycle the generated fine by-products. In many cases it is not economical or generates little added value to sell and transport the materials to other plants for recycling. For these plants, the best recycling concept is to agglomerate the by-products, which reach approximately 10% of mass of the produced DRI capacity, such as dust from the material handling systems, oxide fines, HBI fines and DRI slurry by briquetting with an inorganic binder system. The cold briquetting process itself is similar to the process shown in Figure 2. The produced briquettes are directly fed into the direct reduction plant (e.g. MIDREX) and may replace ferrous materials like iron ore or pellets in the reduction shaft.

New developments: The recycling concept for by-products generated in DRI plants is not yet commonly used on a large scale. The great economic value of such a project is determined by the high iron ore and pellet costs, compared to a relatively low operating cost and investment cost for such a plant. Primetals, based on its experience from similar applications with cold briquetting plants, has invested considerably in laboratory testing to verify the briquetting properties and selection of appropriate binders and process parameters. To verify the right recipe for briquetting such materials and their combinations, several tests on laboratory scale as well as reduction tests simulating gas atmospheres of DRI plants were carried out. In Figure 5 the oxide briquettes before and after passing the DRI shaft under reduction gas atmosphere are shown. The results fulfill the requirements of a direct reduction shaft concerning the low temperature disintegration (550°C). In Figure 6 the promising results are summarized and compared with iron ore pellets. These results are promising in the sense that briquettes were produced that are stable under the reduction conditions. The actual basket tests results agreed well with the laboratory tests results, so that conclusion from the laboratory tests can be applied to the actual plant conditions.


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Figure 5. Soft basket tests in reduction shaft [2] a) before test; b) deformed soft basket after test

Figure 6. Summary of test results

3. ADVANTAGES OF PRIMETALS COLD

BRIQUETTING - Saving of Raw Materials, substitution of

pellets or lump ore - Compact plant layout, easily integrated in

integrated plant or DRI plant layout - Avoid Depositing of By-Products, avoid

cost of depositing, save space - Low overall CAPEX, low investment cost,

short payback time - Minimize Handling, use of materials

directly in the main process - Low OPEX compared to cost of pellets or

lump ore - Environmental compatibility: 100%

recycling of by-products, processing of in-plant waste materials

- Fully automated process control and plant operation

4. CONCLUSION Many iron and steel plants already practice recycling of by-products to a certain extent, however there is still room for increasing the value creation by optimizing the recycling concept and finding new innovative applications. One of these applications is recycling of by-products in DRI plants by cold briquetting and using the briquettes as iron ore or pellet substitute. A similar concept is used in integrated plants by cold briquetting of by-product fines and recycling the briquettes in blast furnaces and BOF converter plants.

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T02 18624b 10 215 361 96,2 92,1 yes 90 90 76,0 25,3T10 18624b 10 150 491 97,7 96,5 yes 81 100 77,4 -T15 18624b 10 338 655 95,3 90,7 yes 87 93 77,8 25,5T16 18624b 10 194 399 97,2 95,3 no - - 76,3 -T21 18624b 5 185 517 91,5 83,3 no - - 80,7 25,8T06 18665b 5 250 718 84,4 78 yes 94 89 88,0 -T07 18665b 5 250 670 92,3 82,5 yes 95 100 86,9 27

comp. Strength [N]

shatter strength [%]

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sample no. test no. br

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251

5. REFERENCES [1] Jörg Schwelberger, Gerald Wimmer,

Christian Brunner, Alexander Fleischanderl: "Innovative solutions for recycling of by-products”, 46 Seminário de Aciaria - Internacional,18.-20. Aug.2015, by, Primetals Technologies Austria GmbH, 2015

[2] Ch. Brunner, J. Schwelberger, A. Fleischanderl; A. Röpke; "Recycling of ferrous by-products in DRI plants", METEC 2015, Düsseldorf, Germany

[3] Ch. Brunner, J. Schwelberger: " Soluciones innovadoras para el reciclaje de produtos ferrosos y la optimización de los costos de producción”, Alacero55, Mexico City, 29.Oct 2014,

Coresponding author: Jörg Schwelberger Primetals Technologies Austria GmbH


252

Izvod iz Izvještaja o održanoj 8. Međunarodnoj konferenciji Environmental and Material Flow Management (EMFM 2018)

U periodu od 14. do 16. novembra 2018., u Zenici je održan 8. Međunarodna konferencija “Environmental and Material Flow Management (EMFM 2018)“, koju je organizirao Mašinski fakultet Univerziteta u Zenici (UNZE), zajednički s partnerima: Univerzitet u Beogradu, Tehnički fakultet iz Bora i Univerzitet primijenjenih nauka iz Trira, Univerzitetski kampus Birkenfeld.

Pitanja zaštite okoliša, klimatskih promjena i politika EU pokazuju trendove rasta sve većeg interesovanja, te je u skladu s tim i konferencija EMFM 2018 imala odličan odziv i obuhvatila radove autora i koautora iz 8 zemalja.

Na zadovoljstvo Organizacionog odbora, konferenciju EMFM 2018 su prepoznale i relevantne institucije kao što su Ministarstvo za prostorno uređenje, promet i komunikacije i zaštitu okoline ZDK i Federalno ministarstvo okoliša i turizma. Pored ministra mr. Fahrudina Brkića iz Vlade ZDK i predstavnika Ministarstva FBiH, gostima su riječi dobrodošlice uputili i predstavnici Univerziteta u Zenici i Mašinskog fakulteta UNZE-a, tj. prorektor prof. dr. Enes Hašić i dekan prof. dr. Fuad Hadžikadunić te, posebno, prof. dr. Šefket Goletić, šef Katedre za okolinsko inžinjerstvo UNZE-a i šef Organizacionog odbora EMFM 2018, pod čijim vodstvom je EMFM 2018 i organiziran.

Trodnevna Konferencija ugostila je preko 90 učesnika, na kojoj su asutori i koautori predstavili 41 naučni i strični rad. Samo plenarni dio je imao šest radova, poglavito o najnovijim dostignućima u oblasti novih metoda upravljanja okolišem, inženjerstva zaštite okoliša, obnovljivih izvora energije i održivog razvoja, uključujući nove alate i nove materijale. U uvodnom dijelu predstavljen je i posebni izvještaj o analizi Energetske strategije BiH i nedavno usvojenog Strateškog plana ruralnog razvoja BiH. Analizu je

uradio tim stručnjaka okupljenih u NVO „Green Building Council“, a podatke do kojih su došli predstavila je prof. dr. Sanela Klarić.


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Dalji rad EMFM 2018 odvijao se u tri sukcesivne sesije te su svi zainteresovani imali priliku predstaviti svoja istraživanja. Trećeg dana učesnici su posjetili laboratorije i centre Univerziteta u Zenici kao završne aktivnosti u sklopu EMFM 2018.

Ovom prilikom se želimo naročito zahvaliti našim sponzorima na njihovoj podršci (abecednim redom, to su bili): ALBA ZENICA d.o.o. Zenica, ArcelorMittal Zenica, Grad Zenica, JP BH Pošta, Tvornica cementa Kakanj (članica Heidelberg Cement Group) i Ministarstvo za prostorno uređenje, promet i komunikacije i zaštitu okoline Zeničko-dobojskog kantona.

S obzirom na sve navedeno, sretni smo da je EMFM 2018 ostvario svoj cilj promoviranja novih naučnih i praktičnih dostignuća u oblasti inžinjerstva zaštite okoliša (i u srodnim područjima) i na taj način dao doprinos podizanju ukupnog nivoa znanja i stručnosti u spomenutim oblastima. Ze organizacioni odbor Prof.dr. Šefket Goletić

Mašinstvo 4 (15), 254 – 258 (2018) N. Surname 1 et al.: TITLE OF PAPER….

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INSTRUKCIJE ZA AUTORE (Style: Times New Roman, 14pt, Bold)

INSTRUCTIONS FOR AUTHORS (Style: Times New Roman, 14pt, Bold)

Name Surname 1, Name Surname 2, Name Surname X (Author's name, Co-author's name - Style: Times New Roman, 11pt, Bold) Authors’Institution (Style: Times New Roman, 11pt) Ključne riječi: abecedni popis ključnih riječi na bosanskom, hrvatskom ili srpskom jeziku (Style: Times New Roman, 10pt) Keywords: Alphabetic list of keywords in English (Style: Times New Roman, 10pt) Paper received: xx.xx.xxxx. Paper accepted: xx.xx.xxxx.

Kategorizacija članka (Style: Times New Roman, 10pt, Bold, Italic) REZIME (Style: Times New Roman, 10pt, Bold) Naslov rada (do 15 riječi). Puna imena i prezimena autora (bez navođenja zvanja i akademskih titula). Rezime rada (do 150 riječi). Rezime treba što vjernije odražavati sadržaj rada. U njemu se navode upotrebljene metode i ističu ostvareni rezultati kao i doprinos rada. Naslov, rezime rada i ključne riječi autori sa ex-YU prostora pišu i na bosanskom, hrvatskom ili sprskom jeziku. Ključne riječi u pravilu su iz naslova rada, a samo eventualno iz sažetka rada. Ovaj dio rada se ne lektoriše i autori su odgovorni za njegovu jezičnu i gramatičku ispravnost. Nakon završetka recenzentskog postupka autori mogu biti zamoljeni da naprave određene popravke ili dopune svoj rad. (Style: Times New Roman, 10pt, Italic)

Categorization of paper (Style: Times New Roman, 10pt, Bold, Italic)

SUMMARY (Style: Times New Roman, 10pt, Bold) Title of the paper (up to 15 words). The full list of authors (without specifying grades and ranks). Summary (up to 150 words). Summary should be as faithfully reflect the content of the paper. It outlines the methods used and highlight the results achieved as well as the contribution of the paper. Title, summary of paper and keywords, authors from ex-Yugoslavia area, write to the Bosnian, Croatian or Serbian languages. Keywords are generally from the title of paper, and just possibly from the summary. This part of the paper is not proofread and authors are responsible for the linguistic and grammatical correctness. After completion of the review process, authors may be asked to make certain repairs or additions to their paper. (Style: Times New Roman, 10pt, Italic)

1. INTRODUCTION (Style: Times New Roman, 11pt, Bold)

Upon its acceptance the article is categorized as follows: original scientific paper, preliminary notes, subject review, professional paper and conference paper. Original scientific papers should report original theoretical or practical research results. The given data must be sufficient in order to enable the experiment to be repeated with all effects described by the author, measurement results or theoretical calculations. Preliminary notes present one or more new scientific results but without details that allow the reported data to be checked. The papers of this category inform about experimental research, small research projects or progress reports that are of interest.

Subject reviews cover the state of art and tendencies in the development of the specific theory, technology and application with given remarks by the author. Such a paper ends with a list of reference literature with all the necessary items in the related field. Professional papers report on the original design of an instrument, device or equipment not necessarily resulting from the original research. The paper contributes to the application of well-known scientific results and to their adaptation for practical use. Papers presented at scientific conferences can also be published in the journal upon the agreement of the conference organizer and the author. (Style: Times New Roman, 11pt, Normal) Papers to be published in the journal Tehnički vjesnik/Technical Gazette, should be written in


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English. The metrology and terminology used in the paper have to meet legal regulations, standards and International System of Units (SI) 1.1. Subtitle 1 (Writing Instructions)

(Style: Times New Roman, 11pt, Bold) The text of the paper is arranged in sections and when necessary into subsections. Sections are marked with one Arabic numeral and subsections with two Arabic numerals, e.g. 1.1., 1.2., 1.3., ... When a subsection is arranged in smaller parts, each of them is marked with three Arabic numerals, e.g. 1.1.1., 1.1.2., ... Further divisions are not allowed. The text has to be organized in the following order: Title of the paper (up to 15 words). Papers should be headed by a concise but informative title that clearly reflects the subject of the paper. Authors' full names (without grades and ranks). Summary-Abstract (up to 150 words) should present a brief and factual account of content and conclusions of the paper, and an indication of the relevance of the new material presented. Title and abstract in Bosnian/Croatian/Serbian (BCS). Only for authors from ex-Yugoslavian area. Alphabetic list of keywords in English and in (BCS). Keywords normally originate from the title and from the abstract. Introduction should state the reason for the work, with brief reference to previous work on the subject. It informs about the applied method and its advantages. Central part of the paper may be arranged in sections. Complete mathematical procedures for formula derivations should be avoided. The necessary mathematical descriptions may be given in an appendix. Authors are advised to use examples to illustrate the experimental procedure, applications or algorithms. In general all the theoretical statements have to be experimentally verified. In Conclusions all the results are stated, and all the advantages of the used method are pointed out. The limitations of the method should be clearly described as well as the application areas. List of references should be brought together at the end of the article and numbered in square brackets in order of their appearance in the text followed by other literature. Coressponding authors' full names followed by the name and address of the institution in which the work was carried on. A List of used symbols and theirs SI units is optional after list of references.

1.1.1. Subtitle 2 (Preparation of Manuscript) (Style: Times New Roman, 11pt, Bold)

The paper should be written using Latin characters. Greek letters may be used for symbols. The volume of the article is limited to 10 pages (A4 format). That includes blanks and equivalent number of characters covered by figures and tables. Number of pages must be even. The text should be sent to the Editorial Board using e-mail. For the text preparing may be used only MS Word for Windows respectively *.doc, *.docx (Word Document) or *.rtf (Rich Text Format) format of records. The text has to be prepared in accordance with this template. The Editorial Board may exceptionally request the CD-ROM with recorded articles and figures and tables. In that case the figures (drawings, diagrams and photographs) should be submitted stored on the CD-ROM in JPG/JPEG, PNG, TIF (TIFF Bitmap) or BMP (Windows Bitmap) format, min. resolution of 300 dpi. Each figure is labelled the same as it is in the paper and recorded format (e.g. fig-1.JPG). If figures inserted into text they must be also with min. resolution of 300 dpi. Latin or Greek characters in italics are used for physical symbols and normal characters for measuring units and numerical values. Text in figures is also written with normal letters. Character size is to be chosen on the basis of the following criteria: after expected figure size reduction a capital Latin character should be about 2 mm high (no less than 6pt). All figures in the Journal will be printed in black and white technique. Coloured figures will be seen only in the PDF format on the Web address http://www.mf.unze.ba/index.php?option=com_content&view=article&id=118&Itemid=107 Tables are created with the word processing program. Each table is positioned in the desired place in the text. In the case of decimal numbers use comas (e.g. 0,253); use a small gap separating the thousands (e.g. 25.000, but not in the case of 1500). The texts under figures and table titles are in English language and in BCS for authors from ex-YU area. Section titles and titles of subsections are typed in small letters only in English language. Equations are numbered with Arabic numerals in parenthesis at the right margin of the text. In the text an equation is referenced by its number in parenthesis like "... from Eq. (3) follows ...".


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Create equations with MS Word Equation Editor (some examples are given below).

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(Notice: If you convert and save your document as a MS Word 2010 file and then add equations to it, you will not be able to use previous versions of MS Word to change any of the new equations.). Figures and tables are numbered with Arabic numerals (1 ÷ n). In the text in figure or table is referenced by its number (e.g. in Fig. 1, in Tab. 1, etc.).

Slika 1. Tekst unutar formula (samo za autore sa ex-YU prostora)

Figure 1 The texts under figures (Style: Times New Roman, 11pt, Italic)

Figure 2. Simplified musculoskeletal model of an arm

(Style: Times New Roman, 11pt, Italic)

When reference to literature is made the publication number from the list of references in square brackets is used like "... in [7] the authors showed ...". In the list of references literature is cited in accordance with examples in Section. 2 COPYRIGHT TRANSFER AGREEMENT Copyright assignment. The author hereby assigns to the journal "Mašinstvo" the copyright in the above article (for U. S. government employees: to the extent transferable), throughout the world, in any form,

in any language, for the full term of copyright, effective upon acceptance for publication. Author's warranties. The author warrants that the article is original, written by stated author/s, has not been published before and it will not be submitted anywhere else for publication prior to acceptance/rejection by "Mašinstvo", contains no unlawful statements, does not infringe the rights of others, and that any necessary written permissions to quote from other sources have been obtained by the author/s. Rights of authors. Authors retain the following rights: - all proprietary rights relating to the article,

other than copyright, such as patent rights, - the right to use the substance of the article in

future own works, including lectures and books,

- the right to reproduce this article for own purposes, provided the copies are not offered for sale.

Co-authorship. If the article was prepared jointly with other authors, the signatory of this form warrants that he/she has been authorized by all co-authors to sign this agreement on their behalf, and agrees to inform his/her co-authors of the terms of this agreement.


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Figure 3. Page setup (Style: Times New Roman, 11pt, Italic)

Figure X. Photography resolution of 300 dpi (min) (Style: Times New Roman, 11pt, Italic) 3. PUBLICATION ETHICS AND PUBLICATION MALPRACTICE STATEMENT The publication of an article in a peer reviewed journal is an essential model for our journal "Mašinstvo". It is necessary to agree upon standards of expected ethical behaviour for all parties involved in the act of publishing: the author, the journal editor, the peer reviewer and the publisher. Publication decisions. The editor of the "Mašinstvo" is responsible for deciding which of the articles submitted to the Journal should be published. The editor may be guided by the policies of the Journal's editorial board and constrained by such legal requirements as shall then be in force

regarding libel, copyright infringement and plagiarism. The editor may confer with other editors or reviewers in making this decision. Fair play. An editor at any time evaluate manuscripts for their intellectual content without regard to race, gender, sexual orientation, religious belief, ethnic origin, citizenship, or political philosophy of the authors. Confidentiality. The editor and any editorial staff must not disclose any information about a submitted manuscript to anyone other than the corresponding author, reviewers, potential reviewers, other editorial advisers, and the publisher, as appropriate. Disclosure and conflicts of interest. Unpublished materials disclosed in a submitted manuscript must not be used in an editor's own research without the express written consent of the author. Contribution to editorial decisions. Peer review assists the editor in making editorial decisions and through the editorial communications with the author may also assist the author in improving the paper. Acknowledgement of sources. Reviewers should identify relevant published work that has not been cited by the authors. Any statement that an observation, derivation, or argument had been previously reported should be accompanied by the relevant citation. A reviewer should also call to the editor's attention any substantial similarity or overlap between the manuscript under consideration and any other published paper of which they have personal knowledge.


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Table 1. Table titles (Style: Times New Roman, 11pt, Normal)

Engineering stress σe / MPa

Engineeringplastic strain εe,pl / %

True stress σt / MPa

True plastic strain εt,pl / %

250,0 0,00 250,8 0,00 250,0 0,21 250,8 0,21 285,7 1,35 290,0 1,34 322,7 2,13 330,1 2,10 358,4 3,06 370,0 3,00 393,1 4,35 411,0 4,24 423,6 6,05 450,1 5,85 449,7 8,76 490,1 8,36 457,0 15,79 530,1 14,59 467,9 21,58 570,0 19,45 475,0 29,77 617,5 25,94

(Style in table: Times New Roman, 11pt, Normal) X. CONCLUSION Paper manuscripts, prepared in accordance with these Instructions for Authors, are to be submitted to the Editorial Board of the "Mašinstvo" journal. Manuscripts and the CD-ROM are not returned to authors. When being prepared for printing the text may undergo small alternations by the Editorial Board. Papers not prepared in accordance with these Instructions shall be returned to the first author. When there are several authors the first author is to be contacted. The Editorial Board shall accept the statements made by the first author. The author warrants that the article is original, written by stated author/s, has not been published before and it will not be submitted anywhere else for publication prior to acceptance/rejection by "Mašinstvo", contains no unlawful statements, does not infringe the rights of others, and that any necessary written permissions to quote from other sources have been obtained by the author/s.

XX. REFERENCES (Style: Times New Roman, 11pt, Normal) [1] P.E. Nikravesh, Computer-Aided Analysis

of Mechanical Systems, Prantice Hall Inc.,Englewood Cliff,NJ,1988.

[2] Gordon Robertson, Graham Caldwell, Joseph Hamill, Gary Kamen, Saunders Whittlesey: Research Methods in Biomechanics, Human Kinetics; 2nd edition, 2014.

[3] Imai, M.: KAIZEN: the key to Japan’s competitive success, Editorial CECSA, Mexico. In Spanish, 1996.

[4] Nemoto, M.: Total quality control for management. Strategies and techniques from Toyota and Toyoda Gosei, Prentice-Hall, Englewood Cliffs, NJ, 1987.

[5] Cheser, R.: The effect of Japanese KAIZEN on employee motivation in US manufacturing, Int J Org Anal 6(3):197–217, 1998.

[6] Aoki, K.: Transferring Japanese KAIZEN activities to overseas plants in China, Int J Oper Prod Manag 28(6):518–539, 2008.

[7] Tanner, C.; Roncarti, J.: KAIZEN leads to breakthroughs in responsiveness and the Shingo prize at Critikon, Natl Prod Rev 13(4):517–531, 1994.

[8] Rink, J.: Lean can save American manufacturing. Reliable plant. http://www.reliableplant.com/Read/330/lean-manufacturing-save. Accessed at 14 April 2014.

[9] SolidWorks, http://www.solidworks.com (12.5.2015)

Coresponding author: Name and surname Institution Email: [email protected] Phone: +xxx xx xxxxxx (Style: Times New Roman, 11pt, Bold)

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ISSN 1512 - 5173

UNIVERZITET U TUZLI

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Laboratorija za istraživanje i razvoj – Termo & fluidna tehnika

Univerzitetska br. 4, 75000 Tuzla, BiH

Tel. +387 (0)35 320 939

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Ukratko O Laboratoriji

Laboratorija za istraživanj e i razvoj – Termo & fluidna tehnika koncipirana je tako da obezbjedi

sprovođenje različitih istraživanja iz oblasti prijenosa topline, mehanike fluida, infracrvene

termografije te različitih problema iz oblasti konverzije energije i energetske efikasnosti .

Istraživanje i razvoj različitih inovativnih rješenja i tehničkih unaprijeđenja iz oblasti termo - fluidne

tehnike, uz aktivnu inkluziju magistarskih i doktorskih kandidata, centralni je zadatak ove zadatak

i cilj aktivnosti u sklopu ove laboratorije.

Oprema Laboratorije:

Laboratorija je opremljena velikim brojem kontrolno – mjernog i nstrumentarija različitog tipa i

namjene, mjernog ranga i osjetljivosti. Također, u smislu numeričke podrške razvoju i istraživanju,

a u sklopu Laboratorije, koriste se numerički paketi : Star CCM+, Comsol, Fluent, SolidWorks, Catia

te drugi specifični komercijalni softwerski paketi.

masinstvo issn 1512-5173 (print) issn (on-line2637-1510...

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