design of an automated food dispensing system for goat's feeding
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Abstract of project paper presented to the Senate of Universiti Putra Malaysia in fulfillment of the requirement for the degree of Master of Innovation & Engineering Design.
ABSTRACT
DESIGN OF AN AUTOMATED FOOD DISPENSING SYSTEM FOR GOATS' FEEDING
BY
MASJURI BIN MUSA @ OTHMAN
NOVEMBER 2006
Chairman: Lt. Col. (R) Ahmad Tarmizi bin Mohamed
Faculty: Engineering
"Auto feeder dispensing system" is a machine, which is designed to feed the
breeds automatically. In this case, goats breed sector has been selected as an
approach to implement this automated food dispensing system machine, due to meet
high local demand of goat's products.
Almost all the goat's breeders in this country, are still implementing the
traditional method and not economical. The farmers or breeders are still feeding the
goats by using an old technique, which is pouring the pallet (food) manually into
each container, which is located at the side of the barn. Farmers could not measure
the exactly amount of pallet needed for each goat if still implement this old
technique. Due to this improper distribution of feeding system, it will cause the
obvious food wastage and may effect badly to the monthly food operation cost. The
method will also take longer time to fill in all the containers and it needs more than
one person if involve with huge farm and huge amount of breeds.
The implementation of the auto feeder machine can avoid the food wastage
because this system is designed to reliably and correctly feed each goat individually.
This computerized feeding system has pre-setting of each goat's feed ration to
include the exact amount of concentrates as required. The machine provides a
comprehensive set of modules; control the feeding system automatically with the
aim of optimizing cost of production of goat products. The automated food
dispensing system is a modular design that provides a flexible and robust system
able to meet the requirements of goats feeding activities.
Abstrak kertas kerja yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi keperluan untuk ijazah Master Inovasi & Rekabentuk Kejuruteraan
ABSTRAK
REKABENTUK MESIN SISTEM PENGAGIHAN MAKANAN SECARA OTOMATIK UNTUK PEMAKANAN TERNAKAN KAMBING
Oleh
MASJURI BIN MUSA @ OTHMAN
NOVEMBER 2006
Pengerusi: Lt. Kol. (B) Ahmad Tarmizi bin Mohamed
Fakulti: Kejuruteraan
"Sistem pengagihan makanan otomatik", adalah merupakan sebuah mesin
yang direkabentuk khas untuk mengagihkan makanan kepada binatang ternakan
secara otomatik. Di dalam kes ini, sektor penternakan kambing telah dipilih
memandangkan permintaan tempatan yang tinggi untuk produk ternakan ini.
Hampir kesemua penternak kambing di negara ini, masih lagi mengamalkan
kaedah penternakan secara tradisional dan tidak ekonomi. Para penternak masih lagi
mengamalkan kaedah tradisional dalam proses pengagihan makanan kepada
kambing ternakan dengan mencurahkan makanan secara manual ke dalam setiap
bekas makanan ternakan yang terletak pada bahagian tepi setiap kandang. Para
penternak tidak akan dapat menyukat dengan betul makanan yang diperlukan bagi
setiap kambing sekiranya kaedah tradisional ini masih terus diaplikasikan. Akibat
daripada sistem pengagihan makanan yang tidak sempurna ini, maka pembaziran
makanan yang begitu ketara berlaku dan seterusnya memberi kesan buruk terhadap
kos operasi makanan setiap bulan. Kaedah ini juga memerlukan masa yang lama dan
lebih daripada seorang pekerja diperlukan untuk mengagih makanan sekiranya
melibatkan jumlah ternakan yang besar atau penternakan secara komersil.
Perlaksanaan mesin pengagihan makanan otomatik ini boleh mengelakkan
pembaziran makanan kerana sistem ini telah direkabentuk untuk mengagihkan
makanan kepada ternakan dengan betul. Sistem pengagihan makanan berkomputer
ini mempunyai suatu sistem kawalan bagi catuan makanan setiap kambing,
disesuaikan dengan jumlah sebenar makanan atau konsentrat yang diperlukan.
Mesin ini menyediakan suatu set modul yang komprehensif, mengawal sistem
pengagihan makanan secara otomatik dengan tujuan utama untuk mengoptimurnkan
kos pengeluaran produk berasaskan karnbing. Mesin ini terdiri daripada sistem
modul yang direkabentuk agar ianya fleksibel, bagi memenuhi keperluan harian di
dalam aktiviti pengagihan makanan kambing.
CHAPTER I
INTRODUCTION
1.1 Introduction
"Automated food dispensing system" or also known as "Auto feeder" is a
system, which is used to distribute foods and feed the breedings automatically by
using controlled mechanical hardware as well as the application of the electronic
programmable database. This system is suitable to implement for the huge capacity
of any kind of breeding sector. In this project, goats breeding sector has been
choosen as an approach to implement this automated food dispensing system due to
the aggressive encouragement from our government to enhance the development of
this sector, and in order to meet the local market demand of goat's product [I].
Goats as a species have a long history as domesticated animals used for
human consumption. Today it is estimated that there are more than 460 million goats
worldwide producing 4.5 million tons of milk and 1.2 million tons of meat annually
[I]. Recent increases in the demand for goat meat from ethnic and health conscious
groups has shifted some emphasis from fiber and milk production to meat
production. It is estimated that there are only 8% of meat goats currently raised in
our country, and most of these needs are imported from other countries such as
Indonesia and Thailand to overcome the local demand. Generally, the meat goat
industry is disorganized and not well defined [2].
Recent increases in immigration and the subsequent increase in ethnic
populations that are familiar with and prefer goat meat, have created an optimistic
and enthusiastic atmosphere among current and potential goat producers. While
interest and optimism have increased, a limited amount of formal work has occurred
toward assessing the feasibility of raising goats within our country. This work
represents a first known attempt at determining the feasibility of raising meat goats
within Malaysia. Understanding that this is a first attempt at determining the
feasibility of raising meat goats in Malaysia, producers or potential producers should
be aware that production costs and marketing niches in Malaysia meat goat industry
can and do differ among producers. Differences among producers can and will affect
the feasibility of producing meat goats. Potential producers should use caution and
careful analysis when deciding to enter the market.
Feed is, without doubt, the main cost incurred in goat production. By using
feed supplements that enhance production, this will not only improve the health of
the breeders, but also be able to offset costs and increase profits. Based from
MARDI's data, almost 80% of the monthly operating cost comes from food [I].
Commonly, in the existing feeding strategy, the farmer will feed the goats by
pouring the foods or required concentrates in the food containers and this may cause
ununiformity in the amount of quantity given. In order to optimize these food
quantities for each station in the barn, as well as to prevent from feed wastage, the
idea of using the automated food dispensing system has been taken placed. The
optimal approach is to feed the goats often with small individually adapted portions.
This method allows the goats to properly digest their feed, promotes good growth
and limits feed waste.
1.2 Background
The automated food dispensing system is one of the main systems, which
can be applied to the goat's breeding sector with huge amount of breeds. It is
designed to reliably and correctly feed each goat individually. This computerized
feeding system has pre-setting of each goat's feed ration to include the exact amount
of concentrates as required. The module provides a comprehensive set of control
system, to control the feeding activity automatically with the aim of optimizing cost
of production of goat products. The automated food dispensing system is a modular
design that provides a flexible and robust system, able to meet the requirements of
goats feeding activities.
However, the auto feeder dispensing system machine has not been applied
yet aggressively in our country. Most of Western and European countries such as the
United State of America, Denmark, Norway, United Kingdom as well as Australia
and New Zealand, the implementation of these auto-feeders dispensing system have
tremendously applied into their sheep farms, which involve thousands of breeds 131.
Since there are huge amounts of breeds, as a result, most of the farms involved many
workers to do all the related breeding process such as cleaning the barn as well as to
feed the breeds. Besides that, one of the most problems facing in the breeding
process is that, the distribution of the exact amount of nutrition food in a very
effective and proper way. The improper distribution of food can caused a lot of feed
wastage and directly it gives bad impact to the food operation cost. In order to
prevent the feed wastage, a proper and an efficient system of feed distribution
should be taken place where by, it will save the food distribution time without the
involvement of too many workers.
As a result, to overcome these critical phenomena, most of the farmers or
breeders have been shifted and focusing to other system, which is more efficient and
involve more cost saving in daily food operation cost. Starting from this point
onwards, the auto feeder dispensing system has been well known and has been used
widely among the breeders in Western and Europe.
Companies who producing and do marketing for the auto feeder dispensing
system is not only limited to the sheep or goat breeding. They also produce this
system to other kind of breeders such as cows, horses, fishes as well as pets.
1.3 Problem Statement
Food is one of the most important factors in any kind of breeding activities.
Food also contributed the most higest cost in the monthly operation cost compare to
others such as health and medication cost as well as contegencies cost. Goats need to
take care of from the quality of the food, the amount of food given, and those
diseases, which are caused by the foods. Non-quality food can effect the breeds
growth and health.
Almost all the goat's farmers in this country, are still implementing the
traditional breeding system and not economical. In other words, the "traditional
system which is not competence". In this traditional system, the goats are let free
during daytime to feed on leaves or grass and all will stay in the barn during
nighttime. The feed areas include rubber farms, coconut oil farms, and fruits farms
as well as around village areas. Due to the improper amount of food nutrition,
therefore the qualities of the food given to the goats are very low. Besides having
leaves and grass as one of the main food, goats also will be given with other special
nutrition food, which is the mixture of few ingredients, known as pallet. This quality
nutrition food will be fed to the goats twice a day and it is a very costly item.
Goat's farmers in our country are still feeding the goats by using an old
technique, which is pouring the pallet into each container, which is located at the
side of the barn as shown in Figure 1.1 [3]. By using this old method, the farmers
could not measure the exactly amount of pallet needed for each goat. They just
simply poured the pallet or nutrition food into the containers to make sure it full.
Due to this improper distribution of feeding system, it will cause the obvious food
wastage and may effect badly to the food operation cost. The method will also take
longer time to fill in all the containers and it needs more than one person if involve
with huge farm and huge amount of breeds and indirectly will increase the overhead
cost. This is the main reason why food operation cost is the highest cost in goats
breeding sector in Malaysia.
Figure 1.1 ; Traditional method of food distribution [3]
Q)
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C M .- VY Q) a - cd 0
3 S i! a 5 !i 3 3 z Q)
S S .d
3 E Q)
2 3 X - C 0 - - 'is C 0 Q) -7
%
CHAPTER I1
LITERATURE REVIEW
2.1 Introduction
Intensive commercial goat's farm sector is one of the main sectors in our
country, which can gain a lot of profits and benefits. The demand for goat's products
such as pasteurize milk as well as its meat among the consumers, lead to the
increment of the goat's farms in Malaysia. Table 2.1 and Table 2.2 below [2], tells
us about the demand of goat's products and its market price in RM. Table 2.3, shows
us about the different of market price in Ringgit Malaysia (RM) per kg between
local live goats and combine gene live goats. According to the Agricultural
Department, presently, our country can only patch about 8% of the local demand on
the goat's products especially on meat and pasteurize milk. The remain of 92% of
the local demand, mostly are imported from other countries such as Australia, New
Zealand, Indonesia, Thailand and Myanmar.
Based on the Table 2.1, on the next page, which gain from the Agricultural
department [2], the demand of imported goats slightly increased from 1996 to year
2000. This data show us that the need is already there and will be succeeded if
manage properly and effectively.
Table 2.1 ; The demand of goat's products and its market price in RM from year 1996 to 2000 [2]
-
Year 2002 2003 2004 2010 (forecast)
Local Output 1.21 1.30 1.50 2.18
Demand 15.10 15.60 16.80 21.30
Percentage (%) 8.0 1 8.33 8.93 10.23
Table 2.2; The differences between market demand and local output
of goat's products [2]
From the table above, the demand are always increased, roughly we can see
the growth always maintained at the above 8%.
Year
1996
1997
1998
1999
2000
Meat
The data from Table 2.3, shows the price of combine gene live goats, where
the level is much better than the local goats (data from the Agricultural department
for the analysis been done from year of 1998 to 2000).
Goat
Weight
(metric ton)
13,804
12,508
1 1,840
12,239
13,956
Sheep
Weight
(metric ton)
25,759
43,773
25,6 17
42,6 16
45,325
Value RM
(000,000)
63.8
66.2
69.7
68.7
69.6
Weight
(metric ton)
10,309
9,233
2,892
8,62 1
3,987
Value RM
(000,000)
6.3
11.0
7.9
11.8
9.2
Value RM
(000,000)
3.3
3.3
1 .O
4.5
3.0
Table 2.3; The price (RM) of female and male genetic combination or local goat [2]
Year
1998
1999
2000
In order to overcome this short demand, the government through other
responsible and related agencies such as Malaysian Agricultural Research and
Development Institute (MARDI), Lembaga Kemajuan Ternakan Negara
(MAJUTERNAK), as well as State Agricultural Development Corporation (SADC),
has been put a lot of effort to encourage Malaysian to involve in this profitable
sector. Government through MARA agency, has been introduced a program to
encourage and attract unemployed graduates to dabble in this sector. Since our prime
minister, Y.A.B. Dato' Seri Abdullah bin Hj. Ahrnad Badawi, has been reintroduced
the idea of Green Book which stress on the importance of agriculture for the
country, more and more local individual has shown their interest in the goats breed
sector. This sector has bright hture and will be succeeded if focus seriously.
Information from Fortune Magazine stated that one of the three industries in
Malaysia, which definitely give a good prospect and gain a good income in 10 years
times, is in the breeding sector.
In order to design the automated food dispensing system, it is good to really
understand the system of the goat's feeding itself. The information such as, what is
the amount of food that needs to be taken everyday and how the distribution of the
Genetic Combination 1 Local Goat (RM pricekg live goat)
Female
Local
6.00
6.00
6.00
Male
Combine Gene 9.00
9.00
9.00
Local
10.00
14.00
14.00
Combine Gene 10.00
14.00
14.00
food to the food containers, which are located at the barn, need to be done. All the
information, later on will be used as a references to design an automated food
dispensing system, which is more efficient to replace and improve the existing
traditional method. With this automated system, hopefully it can contribute a
valuable value to our breeding sectors and meet our local demand in goat's products.
Through the search which done by the Veterinary Department, the amount of
food for each goat depend on its weight. Graph 2.1, shows us about the total amount
of food given for each goat per day.
1000
A 900 m - 800 '0
8 700 LL r 600 0 = 500 a
400
4 300 - g 200
+ 100
0 20 30 40 50 60
Goat's Weight (kg)
Graph 2.1 ; Total amount of food (g) given to each goat depend on the goat's weight (kg) [2]
Besides the weight of the goat, the factor of goat's age is also play an
important role in goats feeding. Table 2.4, tells us about the total amount of food
given based from the goat's age [2].
+I- 50 to 100 +I- 150 to 350 +I- 400 to 600
6 and above +I- 600 to 650
Table 2.4; The total amount of food given (g) based from the goat's age. [2]
The information from Graph 2.1 and Table 2.4, shows us that, the relation
between the goat's weight and age plays an important roles for the feeding amount.
In this particular case, we assume that all breeders are 5 to 6 months in age with the
weight is around 30kg for each goat. Therefore, the roughly amount of food given is
about 500g for each goat daily [2]. Base from this information, we can determine the
size of the food container of the automatic food dispensing system which going to
design later. The size of the food container is also depending on the quantity of the
goats in the barn to feed. If it involve with big quantity of goats, therefore the food
container need to replace with other size to cater with the goat's quantity, which
need to be fed.
2.2 Types of Auto feeder Dispensing System
There are two types of auto feeder dispensing system in the market, depend
on their application, design or shape and how the breeds are feed, the food area
location, as well as the size or capacity of the breeds.
The types are:
i) Static auto feeder dispensing system.
ii) Self-moveable auto feeder dispensing system.
2.2.1 Static Auto feeder Dispensing System
Static auto feeder dispensing system, normally applied to a small and
medium scale of breeding. This equipment is not limited to feed indoor-kept breeds.
The auto feeder system is equipped with lid and suitable seals to permit to be
operated outside. The programmable software is implemented to control all the
processes and activities done by the auto feeder system. There is an auto feeder
system, which only allows one goat to eat at one time as shown in Figure 2.1 on the
next page. This kind of auto feeder machine consists of two separate sections. One
of the sections is called control panel system that controls the auto feeder
automatically when feeding the goats. The control panel system will control the
amount of the food, which need to be given for each goat. The other section is a
place to feed the goats, which is also known as feeder section. Battery is used as a
power supply to generate the power. Once, when the goat is at the feeder section, the
control panel system will start to operate by allowing the feed to discharge from the
main food container into the other container with a certain amount of food that has
been set automatically. After the goat finish eating, the next goat will take place and
this process is a repeatable process. The disadvantage of this auto feeder system is
that only one goat can eat at one time.
There is an auto feeder system using the gravity concept as shown in the
Figure 2.2 [4]. The quantity of food can be set automatically and will discharge from
the main food container, which is located on the top of the machine to the bottom
food container through few chutes. The feeding period can also be set up
automatically. For this design, the control panel section is located inside the main
food container to prevent it from the weather conditions or to avoid from any outside
disturbances. This type of auto feeder system has simple design and the good thing
about this design is that it can feed about 16 to 18 goats in one time. The
disadvantage is that, goats have to share their food and possibility to quarrel to have
the food can be happened. Besides that, the food quantity of each goat taken cannot
be controlled and this may cause unbalance nutrition. Other static types of auto
feeder system are shown in Figure 2.3, Figure 2.4 and Figure 2.5 in Appendix
section [3], [5].
Control Panel Section
Feeder Section
Figure 2.1 ; Static Auto-feeder system [3]
Main Food Container
Bottom Food
Container
Chutes
Figure 2.2; Static Auto feeder system (Gravity type) [4]
2.2.2 Self-moveable Auto feeder Dispensing System
The other type of auto-feeder system is a self-moveable type. The application
of the self-moveable auto feeder dispensing system is more suitable for huge
capacity of breeding. This type of auto-feeder system handles group feeding from an
overhead, monorail mounted wagon and distributes food from the main station to
each barns as shown in Figure 2.6 and Figure 2.7 [ 5 ] . This method is much more
effective, save a lot of time, and not involved many workers. However, the first time
set-up cost will be much higher if compared to the static type due to the
implementation of more advanced technology. The machine itself is a dedicated auto
feeder machine where it is run by using patented feeding software. Every processes
or activities done by the machine are controlled automatically. Parameters such as
setting the feeding time (the auto feeder machine will start to move automatically to
distribute the food when reach the time which has been set), amount or quantity of
feeding, or even the speed of the machine can be set up with control panel attached
on the machine.
Top Monorail /
Control Panel.
Figure 2.6; DeLaval feed wagon R135 (Rail type) [5]
Control Panel
Top Monorail
Chutes
Figure 2.7; DeLaval feed wagon FCC380 (Rail type) [5]
Flow chart 2.1, on the next page, shows us roughly about the basic function
of the auto feeder dispensing system machine.
Flow-chart 2.1 ; General Process Flow of the Function of the Auto Feeder Dispensing System Machine
flective sensor v
:he presence of
7- the reflective tape
The re --------- sense t . * The reflective sensor
Auto-Feeder Machine will - - - - - - - - (at side panel) sense the stop moving presence of the
reflective tape (at food containers)
Auto-Feeder Machine start to move
+--------------------- Pallet flows out of the main food container through the chutes
The Auto-Feeder Machine will move backwards to the
starting point
+ The valve of the feeder's
system will close
After certain quantity 4 ------- of pallet has been
poured into the food container, the
Level sensor is on --------- b
actuator's sensor will give signal to the valve to close.
2.3 Design of the Auto feeder Dispensing system
First of all, the conceptual design need to be considered before proceed to the
detail and final design. To have the conceptual design, all the information regarding
to the auto feeder dispensing system will be collected. The information related to the
goat's breeding sector such as the types of barn which is normally built in our
country, methods used to feed the breeders as well as types of food given to the
breeders are also need to be concerned. To have a clear picture of the real situations
about the goat's breeding sector, a visit has been done to one of the well known
place, which is called KAPRIMA, located at Lendu, Melaka.
2.4 Technical Drawings and Design Analysis
One of the design's software, which is called Solidworks, will be used to
draw the technical drawings of the overall auto feeder dispensing system. The
drawings will include the 3D drawings as well as the 2D drawings. On the other
hand, the analysis of the structure of the auto feeder system will also be done. These
will involve Finite Element Analysis (FEA), an analysis software which is called
NASTRAN-PATRAN, where the purpose of using this software is to find out the
Von Mises of the structure.
2.5 Computer-Aided Engineering (CAE)
Computer-Aided Engineering (CAE) refers to computer software and
hardware systems used in the analysis of engineering designs to validate functional
performance. Computer-Aided Design (CAD) is sometimes used interchangeably
with CAE [6] .
CAE systems can be separated into four main categories which are:
i) Dynamic analysis.
ii) Finite element analysis (FEA).
iii) General purpose.
iv) Others.
2.5.1 Dynamic Analysis
Dynamics analysis include the kinematics and kinetics of bodies, that is, the
motion and the forces and moment that cause motion. Solid modeling packages, for
example, will mate parts into an assembly, and that we can manipulate various parts
to animate their relative motion. However, in the dynamics analysis package such as
Working Model, or ADAMS, we can apply specified loads to the parts and the
package will calculate their resultant motion using fundamental equations of physics
and a variety of numerical methods. These packages simulate behavior based on
physics, whereas CAD solid modeling packages illustrate motion. Since kinematics
and kinetic based packages are based on the physics of the problem, they can
analyze a number of behaviors including:
i) Positions, velocities as well as accelerations.
ii) Contacts and collisions.
iii) Joint forces, shaking forces.
iv) Relative motions.
2.5.2 Finite Element Analysis (FEA)
Finite Element Analysis (FEA) is a method that essentially divides a part into
smaller discrete elements to analyze the functional performance of a part. Used in
many engineering fields, the process begins with the creation of a geometric model
using CAD software. Solid modeling packages can export files to FEA and some
can communicate directly with FEA packages. The part is subdivided into a mesh of
smaller finite elements connected at nodes. Loads are then virtually applied to the
part. Using hndarnental equations from physics and engineering, an FEA package
can analyze a number of behaviors including:
i) Stresses and strains throughout the part.
ii) Factor of safety.
iii) Buckling of parts in compression.
iv) Temperature gradients and resulting heat transfer.
v) Fluids pressures and flows.
vi) Natural frequencies of vibration.
vii) Displacements of nodes.
2.5.3 General Purposes
General purpose software refers to computer applications covering word
processing, spreadsheets, mathematics, oral presentations, and project management
such as MSWord, Excel, MathCAD, Powerpoint as well as MSProject where by all
these software can help us to complete the daily tasks more efficient.
2.5.4 Others
Other computer-aided engineering application include:
i) Quality function deployment - applications that facilitate the
development of houses of quality such as QFDCapture.
ii) Material selection - specialized software that aids in screening materials
such as GRANTA design, which implements Ashby's methodology.
iii) DFMA - applications that facilitate design for assembly andlor design
for manufacturer analyses such as the Boothroyd-Dewhurst package.
iv) Systems simulation - such as MATLAB Simulink, which analyzes the
transient and steady state behavior of multicomponent electrical and
mechanical systems.
v) Variance analysis - applications that compute tolerances stacks in
assemblies.
2.6 Materials Selection
This section will describe about the basic concept of how to do the materials
selection. As we know that material has attributes: its density, strength, cost,
resistance to corrosion, and so forth [6] . A design demands a certain profile of these:
a low density, a high strength as well as a modest cost. The problem is that of
identifying the desired attribute profile and then comparing it with those of real
engineering materials to find the best match.
2.6.1 The Selection Strategy
There are two main steps, which called screening and ranking, and
supporting information, as shown in Flow chart 2.2.
2.6.1.1 Screening and Ranking
Unbiased selection requires that all materials are considered to be candidates
until shown to be otherwise, using the steps detailed in the boxes of Flow chart 2.2
[17]. Firstly, screening, eliminates candidates which cannot do the job at all because
one or more of their attributes lies outside the limits imposed by the design. For
example, the requirement that the component must function at 250°c, imposes
obvious limits on the attributes of maximum service temperature, which successful
candidates must meet. We refer this as property limits.
All Materials
Screening: apply property (Eliminate candidates which can't do the job)
I Ranking: apply material indices (Find candidates which can do the job well) I
Subset of Materials
I
w
Supporting Information (Handbooks, specialized software, expert systems,
CD-ROMs, website)
I Prime Candidates I
I Local Conditions I I (Does the choice match local needs, expertise?) I
* Final Material Choice
Flow-chart 2.2; The strategy for material selection. The main steps are enclosed in bold boxes [17].
However, the property limits do not help with ordering the candidates that
remain. To do this we need optimization criteria. They are found in the material
indices, which measure how well a candidate, which has passed the limits, can do
the job. Familiar examples of indices are the specific stiffness E I p and the specific
strength of l p (E is the Young's modulus, o, is the failure strength and p is the
density). The materials with the largest values of these indices are the best choice for
a light, stiff tie-rod, or a light, strong tie-rod respectively [17]. On the other hand, to
summarize this, we can say that the property limits isolate candidates which are
capable of doing the job, whereas material indices identify those among them which
can do the job well.
2.6.1.2 Supporting Information
The outcome of the screening step is a shortlist of candidates, which satisfl
the quantifiable requirements of the design. To proceed further we seek a detailed
profile of each, which is supporting information as shown in Flow chart 2.2.
Supporting information differs greatly from the property data used for
screening. Typically, it is descriptive, graphical or pictorial: as for example, the case
study, which involved with uses of the material, details of its corrosion behavior in
particular environments, information of availability and pricing, experience of its
environmental impact. Such information is found in the handbooks, supplier's data
sheets, CD-based data sources and the worldwide webs. Supporting information
helps narrow the shortlist to a final choice, allowing a definitive match to be made
between design requirements and material attributes.
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