SECTION COMPOSITE MATERIALS

1. SECTION COMPOSITE MATERIALS

2. COMPOSITE MATERIALS • Classical Lamination Theory • Composite Material Definition • QUAD4 and TRIA3 elements • Ply Data Recovery • Composite Failure Theorems Post Processing Not Supported in MSC.PATRAN

3. Ply Definition • Typically a ply is a flat group of fibers imbedded in a matrix. • The matrix is usually an isotropic material that holds the fibers together. • In a ply called a tape, the fibers are unidirectional. • In a ply called a cloth, the fibers are woven at 0 and 90 degree directions.

4. Tape Plies • Fiber: • Unidirectional in tape • direction is the 1 axis of the ply coordinate system • Matrix: • glue that holds fibers together • matrix direction is the 2 axis • 90 degrees to the 1 axis • Material properties are: • 2D orthotropic material in Patran • MAT8 in Nastran

5. MAT8 bulk data entry • Defines the ply orthotropic properties. • Elastic properties are E1, E2, NU12, G12, G1Z, G2Z. • Allowables are Xt, Xc, Yt, Yc, S. • Use STRN if allowables are in units of strain. • F12 is for the Tsai-Wu failure theorem. • Thermal coefficients of expansion are A1 and A2, • initial temperature is TREF, • density is RHO, • damping is GE. • The example below is typical for a graphite/epoxy tape. .bdf file extract mat8, 1, 20.+6, 2.+6, 0.35, 1.5+6, 1.6+6, 1.4+6, 1.3-4,+ +, -2.3-7, 4.5-6,, 1.1+5, 1.05+5, 1.2+4, 1.5+4, 2.+4

6. Patran 2D Orthotropic Materials: Create/ 2d Orthotropic/ Manual Input Material Name Input Properties Linear Elastic Apply Input Properties Failure Apply

7. Composite Material • Stack of plies • Each ply has a different direction, material, and thickness • Composite properties are calculated in the material coordinate system (Xm, Ym, Zm) • Zm is the same as the element Z axis (Ze) • Xm is either an angle relative to element G1G2 vector or is the projection of the X axis of a defined coordinate system • Positive angles are defined by right hand rule around Zm

8. PCOMP bulk data entry • Defines the composite layup. • The example composite below is an 8 ply layup, symmetric about it’s centerline, with an equal number of plies is each of the 0, +-45, 90 degree directions. .bdf file extract pcomp,1,,,5000.0,hill,,,,+ +,1,.0054, 0.0,yes,1,.0054, 45.,yes,+ +,1,.0054,-45.,yes,1,.0054, 90.,yes,+ +,1,.0054, 90.,yes,1,.0054,-45.,yes,+ +,1,.0054, 45.,yes,1,.0054, 0.0,yes

9. Patran Composite Materials: Create/ Composite/ Laminate Click on tape property name for each of the plies Thickness for all layers: .0054<cr> Orientations: 0 45 –45 90 90 –45 45 0 Load Text Into Spreadsheet Apply

10. CQUAD4 bulk data entry • Defines the composite plate. • Material coordinate system can be defined one of two ways: • MCID – (integer) - ID of a user defined coordinate system who’s X-axis is projected onto the element to define the element’s material coordinate system’s X-axis. This along with the Z-axis of the element coordinate system defines the material coordinate system. • THETA – (real) - an angle between the G1G2 vector of the element and the X-axis of the material coordinate system. The positive sense of this angle is the right hand rule direction around the element’s Z-axis. cquad4,1,1,1,2,3,4,99 cquad4,1,1,1,2,3,4,25.0

11. Patran Composite Properties Properties: Create/ 2D/ Shell Option: Laminate Input Properties Click on composite material name Click on coord. sys. for projection to material coord. sys. OK Select elements Apply

12. Patran Material Coord. Z-axis Elements: Verify/ Element/ Normals Draw Normal Vectors Apply

13. Patran Material Coord. X-axis Properties: Show/ Shell Orientation Angle Apply

14. Patran Ply Output Request Analysis: Analyze/ Entire Model/ Full Run Subcases/ Create Output Requests/ Advanced/ Element Stress Ply Stresses OK Apply

15. Patran Ply Stress Results Attach xdb: Results: Create/ Quick Plot Result/ Stress Tensor Position/ Layer 1 Quantity/ X Component Apply

16. Composite Failure Indices • Hoffman: • Hill: • Tsai-Wu: s1, s2, t12 are ply stresses from the Nastran analysis X, Y, S are ply stress allowables from the PCOMP bulk data entry F12 is experimentally determined

17. Composite Failure Indices e1, e2, g12 are ply strains from the Nastran analysis X, Y, S are ply strain allowables from the PCOMP bulk data entry (set STRN term on PCOMP to 1.0) • Max Strain: • Three failure indices • One for each direction • Uses strain allowables • Max Stress: • Same as Max Strain but allowables are in stress units s1, s2, t12 are ply stresses from the Nastran analysis X, Y, S are ply stress allowables from the PCOMP bulk data entry

18. Nastran Failure Index Output 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 STRESSES/STRAINS) (INTER-LAMINAR STRESSES) MAX OF FP,FB FOR ALL PLIES 1 HILL 1 6.6183 0.1776 2 4.1766 0.1822 3 14.5333 0.0315 4 20.0144 20.0144 *** 2 HILL 1 1.8251 0.1288 2 0.9096 0.1322 3 4.0140 0.0228 4 9.5973 9.5973 *** 3 HILL 1 6.0914 0.1912 2 8.4410 0.1961 3 7.4905 0.0339 4 10.2642 10.2642 *** 4 HILL 1 0.0641 0.1153 2 0.8806 0.1183 3 8.7623 0.0204 4 19.9326 19.9326 *** • Printed in the f06 file if allowbles on PCOMP bulk data entry are present. • Failure index display not supported in Patran. .f06 file extract