final structure - copy

Upload: kaanberki

Post on 02-Apr-2018

215 views

Category:

Documents


0 download

TRANSCRIPT

  • 7/27/2019 Final Structure - Copy

    1/38

    ISTANBUL TECHNICAL UNIVERSITY

    FACULTY OF AERONAUTICS AND ASTRONAUTICS

    UCK 328E-STRUCTURAL DESIGN

    Instructor: Prof. Dr. Zahit Mecitoglu

    Term Project: Structural Design And Analyses Of A Wing Of ATA

    Unmanned Aircraft

    110090052 Kaan Berki KARABAY

    110090053 Cemre UNAL

    110110083 Selahattin GOKCEN

    Spring, 2013

  • 7/27/2019 Final Structure - Copy

    2/38

    i

    INDEX

    Page No

    INDEX ..................................................................................................................................... 2TABLE LIST .......................................................................................................................... 2

    FIGURE LIST ........................................................................................................................ 3

    1. INTRODUCTION .............................................................................................................. 5

    2. GEOMETRY and MATERIAL ........................................................................................ 6

    2.1 Geometry ....................................................................................................................... 6

    2.2 Material ....................................................................................................................... 10

    3. LOADING CONDITIONS .............................................................................................. 11

    4. FINITE ELEMENT METHOD ...................................................................................... 16

    5. RESULTS OF ANALYSES ............................................................................................. 20

    6. EVALUATION ................................................................................................................. 34

    BIBLIOGRAPHY ................................................................................................................ 36

    ATTACHMENTS...................................................................................................................37

    TABLE LIST

    Page No

    Table 2.1 : Material Numbers..........................................................................................9

    Table 2.2 : Properties Of Components...........................................................................10

    Table 2.3: Mechanical Properties of Balsa ...............................................................10

    Table 2.4: Mechanical Properties of Carbon Pipe ....................................................11

    Table 3.1: The Parameters Of The ATA Aircrafts.........................................................12

    Table 5.1: Convergency Of Meshes...............................................................................28

    Table 5.2 :Vibration Frequencies Of 5 Modes Of The Wing(Hz)................................28

    Table 5.3: The Result Of Buckling Analysis For First Modes.......................................31

    Table 5.4: The Reaction Forces In Y Direction..............................................................33

  • 7/27/2019 Final Structure - Copy

    3/38

    ii

    FIGURE LIST Page No

    Figure 1.1 : A Sample Image Of ATA Unmanned Aircraft .................................6

    Figure 2.1: Top View Of The Wing And Dimensions Of First Geometry...................6

    Figure 2.2 : Side View Of The Wing And Dimensions Of First Geometry]................7

    Figure 2.3 : The General Image Of Wing................................................................7

    Figure 2.4: Top View Of The Wing And Dimensions Of Final Geometry..................8

    Figure 2.6: Cross Section Of Carbon Pipe (Thickness : 1 mm)................................8

    Figure 2.7 : Cross Section Of Spar (Thickness : 4 mm)...........................................9

    Figure 2.8 :Display of Components According To Real Constant Numbers...............9

    Figure 3.1: Lift Distribution Of The Single Wing..................................................13

    Figure 3.2 : The Calculation Of Parasite Drag Coefficient......................................14

    Figure 3.4 : The Pressure Distribution On Wing....................................................15

    Figure 3.5: Pressure Distribution On The Rib At The Root.....................................15

    Figure 4.1: SHELL 63 Elastic Element ...........................................................16

    Figure 4.2: The Meshed Carbon Pipe...................................................................17

    Figure 4.3: The Meshed Spar...............................................................................17

    Figure 4.4: The Meshed Structure Containing All Components...............................18

    Figure 4.6 : Boundry Conditions..........................................................................19

    Figure 5.1: Displacement Values Of First Design (Max:53 mm).............................20

    Figure 5.2: Von Mises Stress Values Of First Design(Max:40 MPa)........................20

    Figure 5.3: Tsai-Wu Failure Criteriation Values Of First Design.............................21

    Figure 5.4: Displacement Values ( Max:67 mm)....................................................22

  • 7/27/2019 Final Structure - Copy

    4/38

    iii

    FIGURE LIST Page No

    Figure 5.5: Tsai-Wu Failure Criteria (Max: 0,87)...................................................22

    Figure 5.6: Von Mises Stress Values Of Carbon Pipe For Nodes..............................23

    Figure 5.7 : Von Mises Stress Values Of Carbon Pipe For Elements.........................24

    Figure 5.8 : Von Mises Stress Values For Spars For Nodes ( Max:12 MPa)...............24

    Figure 5.9 : Von Mises Stress Values Of Ribs For Elements.....................................25

    Figure 5.10: Von Mises Stress Values Of The Spar For Nodes(Max:6.3MP................26

    Figure 5.11: Von Mises Stress Values Of The Spar For Elements(Max:6.3 MPa.........26

    Figure 5.12: General Image Of Distribution Of Von Mises Stress Values For

    Nodes (Max:46 MPa).........................................................................................27

    Figure 5.13: General Image Of Distribution Of Von Mises Stress Values For

    Elements (Max:47 MPa).........................................................................................28

    Figure 5.14: Image Of 1th Mode Of Wing (Max Displacement: 207.3 mm).................29

    Figure 5.15: Image Of 2nd Mode Of Wing (Max Displacement: 197 mm)...................29

    Figure 5.16: Image Of 3rd Mode Of Wing (Max Displacement: 199 mm)....................30

    Figure 5.17: Image Of 4th Mode Of Wing (Max Displacement: 199 mm)....................31

    Figure 5.18: Image Of 5th Mode Of Wing (Max Displacement: 277 mm).....................31

    Figure 5.19: Front View Of Buckling Analysis For 1st Mode.........................................32

    Figure 5.20: Isometric View Of Buckling Analysis For 1st Mode...................................32

    Figure 5.20: Side View Of Buckling Analysis For 1st Mode............................................3

  • 7/27/2019 Final Structure - Copy

    5/38

    1

    1.INTRODUCTION

    An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft

    without a human pilot on board. Its flight is controlled either autonomously by computers in

    the vehicle, or under the remote control of a pilot on the ground or in another vehicle. [1]

    ATA unmanned aircraft was designed and built for the competition named Desing

    /Build/Fly that was organized by the supports of American Cessna Aircraft Company and

    Rahytheon Rocket Systems in 2012, April. ATA Team was all consisted of students of

    Istanbul Technical University, Faculty of Aeronautics and Astronautics. In this competition,

    ATA Team became 4th that was the best success ever among very popular univercities like

    MIT, Illnois, Virginia Technical Univercity.

    In this study, the wing of the aircraft was designed and analyzed in CATIA V5 and

    ANSYS 14.5, respectively. All the calculations were done in Microsoft Office EXCEL.

    First geometry of wing was designed. Because of importance of lightness, balsa and

    carbon are choosen as materials for skin and ribs, respectively. SHELL 63 Elastic Shell

    element was used for finite element model. Lift and drag forces was calculated by appropriate

    equations. These processes were discussed in next chapters in details. Von Mises stress values

    were compared to allowable stresses values. The convergency of meshes was examined and

    found proper. After providing stress and displacement conditions, Tsai-Wu failure criteriation

    and modal analysis under just gravitational load were done. At the end, total weight of the

    wing was calculated. Results of analyses were examined in evaluation part. The sources that

    were researched were indicated in the bibliography part. A sample image of ATA unmanned

    aircraft was shown in Figure 1.1 .

  • 7/27/2019 Final Structure - Copy

    6/38

    2

    Figure 1.1 : A Sample Image Of ATA Unmanned Aircraft [2]

    2. MATERIAL AND GEOMETRY

    2.1. Geometry

    2.1.1 First Geometry

    For airfoil geometry, MH114 was chosen by designer . With the given data, first geometry

    was created. The first geometry of the wing was shown in Figure 2.1, 2.2, 2.3 .

    Figure 2.1: Top View Of The Wing And Dimensions Of First Geometry

    65 mm 715 mm

    59.2 mm

    177.3 mm

    65 mm

    RootTip

    61.1 mm

  • 7/27/2019 Final Structure - Copy

    7/38

    3

    Figure 2.2 : Side View Of The Wing And Dimensions Of First Geometry

    Figure 2.3 : The General Image Of Wing

    2.1.2. Final Geometry

    After analyzing the first wing, there were found unnecessary parts and some parts were

    substracted, then the length of carbon pipe was shorten. The final geometry of the wing was

    shown in Figure. There used totally 13 ribs.

    10 mm

    177,3 mm59,2 mm

    Carbon Pipe

    Rib

    Spar

  • 7/27/2019 Final Structure - Copy

    8/38

    4

    Figure 2.4: Top View Of The Wing And Dimensions Of Final Geometry

    Figure 2.5: Side View Of The Wing And Dimensions Of Final Geometry

    Chord length and wing span were 236.5 mm and 780 mm, respectively.According to

    these dimensions, wing area equals to 0,185 m. The carbon pipe had offset. Because the

    offset was mounted to fuselage and connection point for the wing.

    Figure 2.6: Cross Section Of Carbon Pipe (Thickness : 1 mm)

    The cross sections of the carbon pipe and spar were shown in Figure 2.6 and 2.7,

    respectively.

    This part was substracted. The new length

    of carbon pipe was 260 mm.

    36.4 mm 23 mm 29.1 mm 48 mm 100 mm

    RootTip

    9 mm 10 mm15 mm

    7 mm

    10 mm

    8 mm

    61.1 mm

  • 7/27/2019 Final Structure - Copy

    9/38

    5

    Figure 2.7 : Cross Section Of Spar (Thickness : 4 mm)

    The cross section areas were considered same for all the structure because of easiness in

    designing process.The thickness of the skin was also considered 1 mm for all the structure.

    The properties of the components were shown in Table 2.1 , 2.2 and Figure 2.8.

    Table 2.1 : Material Numbers

    Material Number 1 Balsa

    Material Number 2 Carbon Tube

    Figure 2.8 :Display of Components According To Real Constant Numbers

    4 mm24.97 mm

    1

    2

    3

  • 7/27/2019 Final Structure - Copy

    10/38

    6

    Table 2.2 : Properties Of Components

    Structure Real Constant Number Thickness

    Rib 1 3 mm

    Skin 2 1 mm

    Spar 3 4 mm

    2.2.Material

    Model aircraft had to be very light and resistent because of the missions of the competition.

    Because of that carbon tube was choosen for the pipe where the wing connected to the

    fuselage. The other parts of the wing was made from Balsa that had very high elasticity

    modulus in x direction. Safety factor was considered 1,3 because of the importance of

    lightness. The mechanical properties of the carbon tube and balsa were shown in Table 2.3

    and Table 2.4, respectively. Also the allowable stresses in different directions were calculated

    in these tables.

    Table 2.3: Mechanical Properties of Balsa [3]

    Elasticity Modulus in X Direction 4600000 MPa

    Elasticity Modulus in Y Direction 110 MPa

    Elasticity Modulus in Z Direction 110 MPa

    Poisson Ratio in XY Plane 0,3Poisson Ratio in YZ Plane 0,00717

    Poisson Ratio in XZ Plane 0,00717

    Shear Modulus in XY Plane 600 Mpa

    Shear Modulus in YZ Plane 600 Mpa

    Shear Modulus in XZ Plane 360 Mpa

    Density 150 kg/m Allowable Stress

    Tensile Yield Strength in X Direction 32,5 MPa 32,5/1,3=25 MPa

    Tensile Yield Strength in Y Direction 27,5 MPa 25,7/1,3=19,8MPa

  • 7/27/2019 Final Structure - Copy

    11/38

    7

    Tensile Yield Strength in Z Direction 27,5 MPa 25,7/1,3=19,8MPa

    Compression Yield Strength in X Direction 19,5 MPa 19,5/1,3=15 MPa

    Compression Yield Strength in Y Direction 16,5 MPa 16,5/1,3=12,7MPa

    Compression Yield Strength in Z Direction 16,5 MPa 16,5/1,3=12,7MPa

    Table 2.4: Mechanical Properties of Carbon Pipe [4]

    Elasticity Modulus in X Direction 142000 Mpa

    Elasticity Modulus in Y Direction 10300 MPa

    Elasticity Modulus in Z Direction 10300 Mpa

    Poisson Ratio in XY Plane 0,27

    Poisson Ratio in YZ Plane 0,0195

    Poisson Ratio in XZ Plane 0,0195

    Shear Modulus in XY Plane 7200 MPa

    Shear Modulus in YZ Plane 7200 MPa

    Shear Modulus in XZ Plane 4824 MPa

    Density 1500 kg/m Allowable Stresses

    Tensile Yield Stress in X Direction 1035 MPa 1035/1,3=796,2 MPa

    Tensile Yield Stress in Y Direction 41 MPa 41/1,3= 31,6 MPa

    Tensile Yield Stress in Z Direction 41 MPa 41/1,3=31,6 MPa

    Compression Yield Stress in X Direction 689 MPa 689/1,3= 530 MPa

    Compression Yield Stress in Y Direction 117 MPa 117/1,3=90 MPa

    Compression Yield Stress in Z Direction 117 MPa 117/1,3= MPa

    3.LOADING CONDITIONS

    Because of the manueveirs of the aircraft the load factor was considered 1.5 . Load factor

    is defined as the as the ratio of the lift of an aircraft to its weight. The total lift for for the one

    wing can be calculated from Formula 1. The total weight of the structure was 18 N.

    (1)

  • 7/27/2019 Final Structure - Copy

    12/38

    8

    The lift force was for two wings. Since one wing was analyzed, the lift force was divided

    by 2. So the total lift force was 13,5 N.

    First, some parameters were needed. The calculated parameters were shown in Table 3.1:

    Table 3.1: The Parameters Of The ATA Aircrafts

    The lift distribution of lift and drag distributions were calculated as follows:

    Lift DistributionThe wing span and the magnitute of circulation an the root of a three dimensional

    wing were 2s and 0. The formulas used in calculations were below:

    With the data of coordinates given, circulation was found. Then inserting the lift force

    formula lift force was found. The details of the calculations were given in attachments. The

    graph of the lift distribution was shown in Figure 3.1.

  • 7/27/2019 Final Structure - Copy

    13/38

    9

    Figure 3.1: Lift Distribution Of The Single Wing

    Drag DistributionFor a wing with an eliptical lift distribution, induced drag is calculated as follows:

    [6]

  • 7/27/2019 Final Structure - Copy

    14/38

    10

    For a wing with an eliptical lift distribution, parasite drag was calculated and shown

    in Figure 3.2 .

    Figure 3.2 : The Calculation Of Parasite Drag Coefficient

    The total drag force was calculated from the formula given below:

    For all the calculations, the freestream density was taken 1,226 kg/m3 and total drag was

    calculated as 2,5653 N. The wing was divided into 12 zones and these zones were divided

    into 4 areas. The areas were shown in Figure 3.3.

    Figure 3.3 : The Different Divided Areas

  • 7/27/2019 Final Structure - Copy

    15/38

    11

    The distributions of drag and lift forces were applied as pressures and shown in Figure

    3.4 and 3.5.

    Figure 3.4 : The Pressure Distribution On Wing

    Figure 3.5: Pressure Distribution On The Rib At The Root

  • 7/27/2019 Final Structure - Copy

    16/38

    12

    4.FINITE ELEMENT MODEL

    After determining the geometry and appropriate element was choosen as SHELL 63 Elastic

    Element. SHELL63 is well suited to model linear, warped, moderately-thick shell structures.

    The element has six degrees of freedom at each node: translations in the nodal x, y, and z

    directions and rotations about the nodal x, y, and z axes. The deformation shapes are linear in

    both in-plane directions. For the out-of-plane motion, it uses a mixed interpolation of tonsorial

    components.The geometry, node locations, and the coordinate system for this element are

    shown in Figure 4.1.

    Figure 4.1: SHELL 63 Elastic Element [7]

    The element is defined by four nodes, four thicknesses, and the orthotropic material

    properties. A triangular-shaped element may be formed by defining the same node number for

    nodes K and L as described in Triangle, Prism and Tetrahedral Elements. The element has

    plasticity, creep, stress stiffening, large deflection, and large strain capabilities.The meshed

    Figures are shown in Figure 4.2, 4.3 and 4.4.

  • 7/27/2019 Final Structure - Copy

    17/38

    13

    Figure 4.2: The Meshed Carbon Pipe

    Figure 4.3: The Meshed Spar

  • 7/27/2019 Final Structure - Copy

    18/38

    14

    Figure 4.4: The Meshed Structure Containing All Components

    Figure 4.5: The Meshed Ribs

  • 7/27/2019 Final Structure - Copy

    19/38

    15

    In the wing structure there used totally 19307 nodes and 19961 elements. Because of

    limitation on the number of elements, there could not be used another mesh. For that reason

    the most appropriate mesh was choosen and element length was 5 mm. So the convergency of

    different meshes could not be examined also.

    For fixing the sutructure spar and carbon pipe were connected to wing. For that reason,

    boundry conditions were applied on spar and carbon pipe. The degree of freedom or the

    surfaces were limited in every direction. It was shown in Figure 4.6.

    Figure 4.6 : Boundry Conditions

  • 7/27/2019 Final Structure - Copy

    20/38

    16

    5.RESULTS OF ANALYSIS

    Results Of Analyses Of First Design

    Figure 5.1: Displacement Values Of First Design (Max:53 mm)

    Figure 5.2: Von Mises Stress Values Of First Design(Max:40 MPa)

  • 7/27/2019 Final Structure - Copy

    21/38

    17

    Displacement and Von Mises Stress values of first design were shown in Figure 5.1

    and 5.2, respectively. The results were found appropriate. But because of the competition

    rules and the missions that ATA unmanned aircraft would do, the lightness was very

    important property. For that reason, the length of the carbon pipe whose density was very high

    compared to balsa material was shorten and the unnecessary parts of the ribs were substracted.

    After these prosesses, desired geometry was created. Also Tsai-Wu failure criteriation of first

    design was shown in Figure 5.3. The structure was stable that failure criteriation value did not

    exceed 1 under the loading conditions.

    Figure 5.3: Tsai-Wu Failure Criteriation Values Of First Design

  • 7/27/2019 Final Structure - Copy

    22/38

    18

    Results Of Analyses Of Final DesignIn this study, static and modal analysis of the components of the wing structure were

    examined. For each component the analysis results were shown below.

    Figure 5.4: Displacement Values ( Max:67 mm)

    Figure 5.5: Tsai-Wu Failure Criteria (Max: 0,87)

  • 7/27/2019 Final Structure - Copy

    23/38

    19

    The displacement values are appropriate for the structure. Maximum displacement

    occured at the tip and the value was found 67 mm. After that Tsai-Wu criteriation was

    examined and found maximum 0,87. Tsai-Wu criteriation values was under 1 and there was

    no problem in the wing structure. The displacement and Tsai-Wu results were shown in

    Figure 5.4 and 5.5 respectively.

    Figure 5.6: Von Mises Stress Values Of Carbon Pipe For Nodes

    Figure 5.6 and 5.7 showed the Von Mises Stress values for nodes and elements,

    respectively. The maximum stress values were found 46 MPa and 47 MPa. Maximum stresses

    were under the allowable stress values and occured at near the middle of the tube as expected.

  • 7/27/2019 Final Structure - Copy

    24/38

    20

    Figure 5.7 : Von Mises Stress Values Of Carbon Pipe For Elements

    Figure 5.8 : Von Mises Stress Values For Spars For Nodes ( Max:12 MPa)

  • 7/27/2019 Final Structure - Copy

    25/38

    21

    Figure 5.9 and 5.10 showed the Von Mises Stress values of spars for nodes and elements,

    respectively. The maximum stress values were found 12 MPa and 17.9 MPa. Maximum

    stresses were under the allowable stress values and occured at the hole of the root rib as

    expected. The great difference between nodal and element solution is the cause of mesh. As

    mentioned before, because of limitation of the number of elements there could not be used

    more elements. Here could not be found exact value. But the locations where the maximum

    stress occured were same. Also the convergency of the meshes were not appropriate for the

    results for ribs. In fact, the geometry of the ribs was the main reason for the irregularity of the

    meshes.

    Figure 5.9 : Von Mises Stress Values Of Ribs For Elements

  • 7/27/2019 Final Structure - Copy

    26/38

    22

    Figure 5.10: Von Mises Stress Values Of The Spar For Nodes(Max:6.3MPa)

    Figure 5.11: Von Mises Stress Values Of The Spar For Elements(Max:6.3 MPa)

  • 7/27/2019 Final Structure - Copy

    27/38

    23

    Von Mises stress values of the spar for nodes and elements were shown in Figure 5.10 and

    5.11 respectively. The maximum stress values were found 6.3 MPa and same. It did not

    exceed the allowable values. As the geometry was rectangle prism and smooth, the meshes

    was excellent. Because of that the convergency of the meshes was good.

    Figure 5.12: General Image Of Distribution Of Von Mises Stress Values For Nodes (Max:46 MPa)

    As understood from the figures none of the Von Mises stress values exceeded the

    allowable values. The values of the carbon pipe were the same with general distribution. So

    the maximum stress occured on the carbon pipe. Because of that reason the skin thickness was

    considered as thin as possible and 1 mm. In addition, the rib on the tip of wing was not same

    with the others. It remained same with first geometry for easiness in the covering prosess.

    There was one hole that carbon pipe connected as understood from Figure 5.12 and 5.13.

  • 7/27/2019 Final Structure - Copy

    28/38

    24

    Figure 5.13: General Image Of Distribution Of Von Mises Stress Values For Elements (Max:47 MPa)

    Table 5.1: Convergency Of Meshes

    Component Element Solution(MPa) Nodal Solution (MPa) Convergency(%)

    Carbon Pipe 47.2 45.9 2.75

    Rib 17.9 11.9 33

    Spar 6.37 6.37 0

    The convergency of meshes were shown in Table 5.1. After Von Mises stress analyses,

    modal analyses of 5 modes of the wing were examined and the vibration frequencies were

    found as shown in Table 5.2. The displacements for 5 modes were shown in Figure 5.14, 5.15,

    5.16, 5.17, 5.18.

    Table 5.2 :Vibration Frequencies Of 5 Modes Of The Wing(Hz)

  • 7/27/2019 Final Structure - Copy

    29/38

    25

    Figure 5.14: Image Of 1th

    Mode Of Wing (Max Displacement: 207.3 mm)

    Figure 5.15: Image Of 2

    nd

    Mode Of Wing (Max Displacement: 197 mm)

  • 7/27/2019 Final Structure - Copy

    30/38

    26

    Figure 5.16: Image Of 3rd

    Mode Of Wing (Max Displacement: 199 mm)

    Figure 5.17: Image Of 4th

    Mode Of Wing (Max Displacement: 199 mm)

  • 7/27/2019 Final Structure - Copy

    31/38

    27

    Figure 5.18: Image Of 5th

    Mode Of Wing (Max Displacement: 277 mm)

    After examining the modal analysis, also buckling analysis of the wing was done for one

    mode. The reason of the negative value in the frequency was reasearched and consulted to

    instructors, but could not be found. The value was shown in Table 5.3 and the images of the

    buckling analyses were shown in Figure 5.19, 5.20 and 5.21.

    Table 5.3: The Result Of Buckling Analysis For First Mode

  • 7/27/2019 Final Structure - Copy

    32/38

    28

    Figure 5.19: Front View Of Buckling Analysis For 1st

    Mode

    Figure 5.20: Isometric View Of Buckling Analysis For 1st

    Mode

  • 7/27/2019 Final Structure - Copy

    33/38

    29

    Figure 5.20: Side View Of Buckling Analysis For 1st

    Mode

    Maximum displacement for buckling analysis for first mode was found 1mm. It was

    considered appropriate.

    Weight Of The StructureTable 5.4: The Reaction Forces In Y Direction

    With Gravity Without Gravity

    First Design -12.208 N -13.530 N

    Final Design -12.501 N -13.530 N

    As understood from Table 5.4, in the first design, the weight of the structure was

    found 1.32N, 137.6 g. After idealizing the wing total weight was found 1.029N, 105 gr.

  • 7/27/2019 Final Structure - Copy

    34/38

    30

    6.EVALUATION

    In this study, design and analyses of the wing of ATA unmanned aircraft that

    participated in 'Design/Build/Fly' competition that was held by the supports of American

    Cessna Aircraft Company and Rahytheon Rocket Systems in 2012, April.

    Design, analyses and calculations were done in CATIA V5 , ANSYS 14.5 and

    Microsoft Office EXCEL program, respectively.

    Firstly, the wing was designed then analyses were done.Lightness was very important

    parameter for ATA aircraft.Because of that load and safety factor were taken 1.5 and

    1.3,respectively.Under these conditions, Displacement and Von Mises stress values were

    found 53 mm and 40 MPa. Results were considered appropriate. But that was not ideal one.

    For finding the desired design the wing was optimized. Because of importance of lightness,

    balsa and carbon are choosen as materials for skin and ribs, respectively. SHELL 63 Elastic

    Shell element was used for finite element model.Structure was modeled with 5 mm-length

    elements. There used 19307 nodes and 19961 elements. Because of limitation on the number

    of elements, there could not be used another mesh. Total lift and drag forces were 13,5 N.

    Dividing the wing 14 zones, again dividing zones into 4 areas, the pressures were applied.

    The wing was attached from spar and carbon pipe to fuselage. Because of that the movement

    of areas that were connected was limited in translation and rotation in x, y, z directions. In the

    results part, displacement values were found suitable for 76cm wing. Then none of Von Mises

    values exceeded the allowable stress values for different components. The convergency of

    meshes were good except mesh of ribs. Because of the geometry of ribs meshes were irregular

    and convergency was too high. Tsai-Wu failure criteriation values were under 1 as expected.

    Then 5 modes of modal analyses were done. The vibrations were evaluated as normal. Then

    buckling analysis was done for one mode and maximum displacement for that mode was 1

  • 7/27/2019 Final Structure - Copy

    35/38

    31

    mm. The sources used and calculations were given in bibliography and attachments,

    respectively. For under all these conditions, the structure can be tought as resistent and could

    do missions successfully.

    This study was just an approximation to real case. In theory, under some assumptions,

    the structure had no problem. But to get exact results, the aircraft had to be flied and tested by

    experts.

  • 7/27/2019 Final Structure - Copy

    36/38

    32

    BIBLIOPGRAPHY

    [1]Url-1 Taken Date : 01.05.2013

    [2]Url-2 Taken Date : 01.05.2013

    [3]Url-3 Taken Date : 06.05.2013

    [4]Url-4

    [5]Url-5

    [6]Url-6

    [7] ANSYS 14.5 Help Topics

    ATTACHMENTS

  • 7/27/2019 Final Structure - Copy

    37/38

    33

    ATTACHMENTS

    Area(mm2) Pressure (Mpa) Applied Pressure(Mpa)

    1. Area (upper) 8071 0,00008784927 0,000114204

    2.Area (upper) 8018 0,00008727239 0,000113454

    3. Area (Lower) 7760 - 0,0000263554.Area (Lower) 7825 - 0,000026182

    1. Area (upper) 8071 0,00008614798 0,000111992

    2.Area (upper) 8018 0,00008558227 0,000111257

    3. Area (Lower) 7760 - 0,000025844

    4.Area (Lower) 7825 - 0,000025675

    1. Area (upper) 8071 0,00008538880 0,000111005

    2.Area (upper) 8018 0,00008482807 0,000110276

    3. Area (Lower) 7760 - 0,000025617

    4.Area (Lower) 7825 - 0,000025448

    1. Area (upper) 8071 0,00008419116 0,000109449

    2.Area (upper) 8018 0,00008363830 0,0001087303. Area (Lower) 7760 - 0,000025257

    4.Area (Lower) 7825 - 0,000025091

    1. Area (upper) 8071 0,00008247669 0,000107220

    2.Area (upper) 8018 0,00008193509 0,000106516

    3. Area (Lower) 7760 - 0,000024743

    4.Area (Lower) 7825 - 0,000024581

    1. Area (upper) 8071 0,00008012876 0,000104167

    2.Area (upper) 8018 0,00007960258 0,000103483

    3. Area (Lower) 7760 - 0,000024039

    4.Area (Lower) 7825 - 0,000023881

    1. Area (upper) 8071 0,00007697721 0,0001000702.Area (upper) 8018 0,00007647172 0,000099413

    3. Area (Lower) 7760 - 0,000023093

    4.Area (Lower) 7825 - 0,000022942

    1. Area (upper) 8071 0,00007276948 0,000094600

    2.Area (upper) 8018 0,00007229162 0,000093979

    3. Area (Lower) 7760 - 0,000021831

    4.Area (Lower) 7825 - 0,000021687

    1. Area (upper) 8071 0,00006711053 0,000087244

    2.Area (upper) 8018 0,00006666983 0,000086671

    3. Area (Lower) 7760 - 0,000020133

    4.Area (Lower) 7825 - 0,0000200011. Area (upper) 8071 0,00005931621 0,000077111

    2.Area (upper) 8018 0,00005892669 0,000076605

    3. Area (Lower) 7760 - 0,000017795

    4.Area (Lower) 7825 - 0,000017678

    1. Area (upper) 8071 0,00004793766 0,000062319

    2.Area (upper) 8018 0,00004762287 0,000061910

    3. Area (Lower) 7760 - 0,000014381

    4.Area (Lower) 7825 - 0,000014287

    1. Area (upper) 8071 0,00002714268 0,000035285

    2.Area (upper) 8018 0,00002696445 0,000035054

    3. Area (Lower) 7760 - 0,0000081434.Area (Lower) 7825 - 0,000008089

    9.Zone

    10.Zone

    11.Zone

    12.Zone

    8.Zone

    3.Zone

    4.Zone

    5.Zone

    6.Zone

    7.Zone

    1.Zone

    2.Zone

  • 7/27/2019 Final Structure - Copy

    38/38