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March 27, 2017, 14:37 |
Coordinate system and orthotropic materials
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#1 |
New Member
Chris
Join Date: Mar 2017
Posts: 2
Rep Power: 0 |
Hello all,
I'm trying to set up a cylindrical coordinate system in order to orient an orthotropic material correctly (Epoxy Carbon Woven (230 GPa) Wet) on a 2D axisymmetric model. The problem is, the radial direction defaults to x, whereas the properties I want to lie radially are defined as z on the material. I thought there may be two ways around this: 1. Change the coordinate system such that z is the radial axis. 2. Change the data so that the properties I want lie on the x axis. I can't figure out how to do 1, so I tried doing 2 and I get an error "The stress-strain matrix of material 1 is not positive definite, which is required for real materials. Being positive definite means that 1.0 - PRXY**2*EY/EX - PRYZ**2*EZ/EY - PRXZ**2*EZ/EX - 2.0*PRXY*PRYZ*PRXZ*EZ/EX must be positive, but is equal to -0.4782336. Consider reducing the Poisson's ratios. EX = 7.5E+09 EY = 5.916E+10 EZ = 5.916E+10 PRXY = 0.3 PRYZ = 4.E-02 PRXZ = 0.3 GXY = 2.7E+09 GYZ = 1.75E+10 GXZ = 2.7E+09. " I've checked that I placed the mechanical data in the correct place a load of times and I'm pretty sure it's right. Any suggestions? Thanks! |
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