复合材料层合板分析

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1、WS-1 WORKSHOP Define a Composite Material NAS121, Workshop , May 6, 2002 WS-2NAS121, Workshop , May 6, 2002 n Problem Descriptionu A 1 in. x 1 in. composite plate is loaded with 2000 #/in. in the Y direction on the top edge, 1000 #/in. in both the X direction and Y direction on the right hand side e

2、dge.u The left side reacts the loads with X, Y, Z, and Ry constraints. WS-3NAS121, Workshop , May 6, 2002 n Problem Descriptionu The layup is made of graphite/epoxy tape and is shown to the right.u The angles shown are relative to the global axis shown.u Thus, the 0 degree ply 1 has its fibers comin

3、g out of the page in the Y direction. u Note that while the positive sense of the angles are right hand rule around the Z global axis in this layup definition, in the Nastran definition, it is around the Z element axis and thus dependent on the element GRID order. WS-4NAS121, Workshop , May 6, 2002

4、n Problem Description (cont.)u The composite plies are graphite/epoxy tape with a thickness of 0.0054 in.u The elastic and strength properties are shown on the right.u The failure theorem to be used is Hill. E11 20e6E22 2e6U12 .35G12 1e6G13 1e6G23 1e6Xt 120 ksiXc 110 ksiYt 13 ksiYc 16 ksiS 14 ksi Sb

5、 5 ksi WS-5NAS121, Workshop , May 6, 2002 n Suggested Exercise Steps1. Create a geometry model.2. Use mesh seeds to define the mesh density.3. Create a finite element mesh. 4. Apply boundary conditions to the model.5. Apply loads to the model.6. Define ply material properties. 7. Check element norma

6、ls8. Define composite material properties. 9. Define a material coordinate system10. Apply the material coordinate system to the elements.11. Submit the model to MSC.Nastran for analysis.12. Attach xdb Results File13. Display ply stresses using MSC.Patran. 14. View ply failure indices in MSC.Nastran

7、15. Change layup to make failure indices below 1.0.16. Analyze the model with the new composite layup17. View the changed ply failure indices WS-6NAS121, Workshop , May 6, 2002 CREATE NEW DATABASE Create a new database called composite1.db:a. In File select Newb. Enter composite1 as the file namec.

8、Click OKd. Choose Default Tolerancee. Select MSC.Nastran as the Analysis Codef. Select Structural as the Analysis Typeg. Click OK a b c d efg WS-7NAS121, Workshop , May 6, 2002 Step 1. Create a geometry modelIn Geometry create the first curve.a. Select Create / Surface / Vertex b. On the Surface Ver

9、tex “n” Lists enter 0 0 0, 1 0 0, 1 1 0, 0 1 0c. Click Applyd. Click the Show Label icon ab cd WS-8NAS121, Workshop , May 6, 2002 Step 2. Use mesh seeds to define the mesh density In Elements, create mesh seeds. a. Select Create / Mesh Seed / Uniform Click on the top edge of the plate to create a me

10、sh seed Then click on the right edge ab c WS-9NAS121, Workshop , May 6, 2002 Step 3. Create a finite element mesh In the Elements menu create surface mesh based on the mesh seeds assigned in the previous steps. a. Select Create / Mesh / Surfaceb. Select Quad as the Elem Shape Click on surface 1 Clic

11、k Apply abc d WS-10NAS121, Workshop , May 6, 2002 Step 4. Apply boundary conditions to the model a bc de gfIn Loads/BCsa. Select Create / Displacement / Nodalb. For New Set Name enter “constraints”c. In Input Data, enter for Translations, for Rotations then OKd. On the top menu click on the Curve or

12、 Edge icone. In Select Application Region click lefthand edge of the surfacef. Click Add and OKg. Click Apply WS-11NAS121, Workshop , May 6, 2002 Step 5. Apply loads to the model a. On the top menu click Reset Graphicsb. Select Create / Distributed Loads / Element Uniform c. Enter “Dist. Load Y” for

13、 New Set Named. In Input Data, Enter for Edge Distr Load , then OKe. In Select Application Region, click on the top curve of the surfacef. Click Add then OK Click Apply bcde gf a WS-12NAS121, Workshop , May 6, 2002 Step 5a. Apply loads to the model (cont.) In a similar way create Dist. Load X:a. Ent

14、er “Dist. Load X” for New Set Name.b. In Input Data, Enter , then OKc. In Select Application Region, click on the right hand side curve of the surface, then Add, then OK. Click Apply abc And then create Dist. Load XY:a. Enter “Dist. Load XY” for New Set Name.b. In Input Data, Enter , then OKc. In Se

15、lect Application Region, again click on the right hand side curve of the surface, then Add, then OK.d. Click Apply e. Note that since the same edge was picked, the loads are combined de WS-13NAS121, Workshop , May 6, 2002 Step 6. Define ply material properties Go to Material menua. Select Create / 2

16、d Orthotropic / Manual Inputb. For Material Name enter “graphite-epoxy_tape” c. Click Input Properties, Select Linear Elastic, enter 20e6, 2e6, .35, 1e6, 1e6, 1e6d. Click OKe. Click Applyf. Click Input Properties again, Select Failure / Stress / Hill and enter 120e3, 13e3, 110e3, 16e3, 13e3, 5000. g

17、. Click OK h. Click Apply again abc d e fg h WS-14NAS121, Workshop , May 6, 2002 Step 7. Check Element NormalsCheck element normals to determine the location of ply 1.Select the Element menu:a. At the top menu click Reset Graphicsb. At the top menu click Hide Labelsc. Select Verify / Element / Norma

18、ls d. Click Draw Normal Vectorse. Click Applya b cd e WS-15NAS121, Workshop , May 6, 2002 Step 8. Define composite material properties Go to Materials:a. Select Create/ Composite/ Laminateb. At Material Name enter 8_ply_symmetric_quasic. Click tape property name (graphite-epoxy_tape) slowly 8 times

19、to make 8 pliesd. At Thickness for all layers enter .0054e. Click on ply 1s empty Orientation cellf. Enter the following into the Insert Orientations box: 0 -45 45 90 90 45 -45 0 . Note that the +-45 degree plies have changed sign due to the element Z axis being in the opposite direction to the glob

20、al Z axis.g. Click Load Text Into Spreadsheeth. Click Apply a bcde hf g WS-16NAS121, Workshop , May 6, 2002 Step 9. Define a material coordinate system Go to Geometry:a. Select Create / Coord / 3Pointb. Enter Coord ID (99 in this case) you want at Coord ID listc. At Origin enter 0 0 0d. At Point on

21、Axis 3 enter 0 0 1e. At Point on Plane 1-3 enter 0 1 0f. Click Apply abcde f WS-17NAS121, Workshop , May 6, 2002 Step 10. Apply the material coordinate system to the elements Go to Properties:a. Select Create / 2D / Shellb. Enter “composite1” at Property Set Namec. At Options select Laminated. In In

22、put Properties click on the composite material name (8_ply_symmetric_quasi)e. At Material Orientation select CID and then click the material coordinate system 99 on the screenf. Click OKg. Click Application Region and click on Surface 1h. Click Addi. Click Apply abd ef gh cg WS-18NAS121, Workshop ,

23、May 6, 2002 Step 11. Submit the model to MSC.Nastran for analysis Go to Analysis:a. Select Analyze / Entire Model / Full Runb. Click Subcasesc. At Available Subcases click Defaultd. Click Output Requestse. At Form Type select Advancedf. At Output Requests, click twice STRESS(SORT1,REAL,VONMISES,BINL

24、IN)=ALL;PARAM,NOCOMPS,-1g. At Composite Plate Opt: select Ply Stresses. Note that PARAM, NOCOMPS,-1 has now changed to 1.h. Click OKi. Click Apply at Subcases and then Cancelj. And click Apply at the Analyze menu a bce f gh i jd WS-19NAS121, Workshop , May 6, 2002 Step 12. Attach xdb Results File Go

25、 to Analysis:a. Select Attach XDB / Result Entities / Localb. Click Select Results File c. Use the Select File tool to find your xdb file in your local Patran directory and click it, in this case, “composite1.xdb”d. Click OKe. Click Apply abc d e WS-20NAS121, Workshop , May 6, 2002 Step 13. Display

26、ply stresses using MSC.PatranTo display the ply 8s 1 direction stresses: go to the Results menu:a. First turn off the geometry in Plot/Erase Geometry Eraseb. Select Create / Quick Plotc. Click Stress Tensord. Click Position then select Layer 8 and click Closee. Click Quantity and select X Componentf

27、. Click Displacements Translationalg. Click Apply bcd efg a WS-21NAS121, Workshop , May 6, 2002 F A I L U R E I N D I C E S F O R L A Y E R E D C O M P O S I T E E L E M E N T S ( Q U A D 4 ) ELEMENT FAILURE PLY FP=FAILURE INDEX FOR PLY FB=FAILURE INDEX FOR BONDING FAILURE INDEX FOR ELEMENT FLAG ID

28、THEORY ID (DIRECT STRESSES/STRAINS) (INTER-LAMINAR STRESSES) MAX OF FP,FB FOR ALL PLIES 1 HILL 1 6.1711 0.0000 2 7.7170 0.0000 3 6.4169 0.0000 4 7.3154 0.0000 5 7.3154 0.0000 6 6.4169 0.0000 7 7.7170 0.0000 8 6.1711 7.7170 * . Step 14. View ply failure indices in MSC.Nastran To view the failure indi

29、ces, open the composite1.f06 file in an editor and search for the following section. It is organized as follows:a. Element numberb. Ply numberc. Ply failure indexd. Ply interlaminar failure indexe. Highest failure index in elementf. Flag if highest failure index is greater than 1.0 (indicating ply f

30、ailure)a b c d e fNote that Patran does not display composite failure indices. WS-22NAS121, Workshop , May 6, 2002 n Hand calculationsu Element 1, ply 2, a 45 degree ply, has the highest failure index of 7.72 but all of the plies have similar values, thus it is difficult to determine which direction

31、 to add plies. However, looking at the terms of Hills theorem may tell us: u Substituting values: u Shows that the 1 direction is the largest contributor to the failure and thus the composite needs more -45 degree plies. u Using this same method, it was found that a 20 ply symmetric layup will give

32、failure indices less than 1.0. The layup is a 0 ply, 4 45 plies, 2 45 plies, and 3 90 plies and then a symmetric layup for the other 10 plies.SXYX 2212221222221 t 92.739.110.014.029.6313 453.13120 378.4501.3313 378.43120 501.3 2222222 eee eeeeee Step 15. Change layup to make failure indices below 1.

33、0 WS-23NAS121, Workshop , May 6, 2002 Step 15a. Change layup to make failure indices below 1.0To change to a new layup: go to Materials:a. Select Modify / Composite / Laminateb. In Laminated Comp. To Modify click 8_ply_symmetric_quasic. At New Material Name enter 0_4x45_2x-45_3x90_symd. In the Lamin

34、ated Composite popup click on ply 1 and then shift click on ply 8 to select all the pliese. Click on Delete Selected Rowsf. Select Text Entry Mode Insert. g. In the Modify Menu on the right, click slowly on graphite-epoxy_tape 10 times, once for each plyh. On Stacking Sequence Convention select Symm

35、etrici. At Thickness For All Layers enter .0054j. Click on the empty ply 1 Orientation cellk. Select Text Entry Mode Overwritel. In Overwrite Orientations enter 0 45 45 45 45 -45 -45 90 90 90m. Click Load Text Into Spreadsheetn. Click Apply ab cd e gk jih nml f WS-24NAS121, Workshop , May 6, 2002 St

36、ep 16. Analyze the model with the new composite layup Go to Analysis:a. Select Analyze / Entire Model / Full Runb. Click Applyc. Click Yes on both overwrite messages. a bcc WS-25NAS121, Workshop , May 6, 2002 Step 17. View the changed ply failure indicesTo view the changed failure indices, again ope

37、n the composite1.f06 file. Note that the failure indices are all below 1.0. F A I L U R E I N D I C E S F O R L A Y E R E D C O M P O S I T E E L E M E N T S ( Q U A D 4 ) ELEMENT FAILURE PLY FP=FAILURE INDEX FOR PLY FB=FAILURE INDEX FOR BONDING FAILURE INDEX FOR ELEMENT FLAG ID THEORY ID (DIRECT ST

38、RESSES/STRAINS) (INTER-LAMINAR STRESSES) MAX OF FP,FB FOR ALL PLIES 1 HILL 1 0.6422 0.0000 2 0.7709 0.0000 3 0.7709 0.0000 4 0.7709 0.0000 5 0.7709 0.0000 6 0.6580 0.0000 7 0.6580 0.0000 8 0.7494 0.0000 9 0.7494 0.0000 10 0.7494 0.0000 11 0.7494 0.0000 12 0.7494 0.0000 13 0.7494 0.0000 14 0.6580 0.0000 15 0.6580 0.0000 16 0.7709 0.0000 17 0.7709 0.0000 18 0.7709 0.0000 19 0.7709 0.0000 20 0.6422 0.7709