Patran determination the first-ply-failure

[Zeck]

Hello,
I have results of FE analysis of laminated structure done using Nastran SOL 400.
Material is linear elastic with failure criterion Tsai-Wu.
Could anyone advice how to determine margin of safety and reserve factors using Patran?
Thanks for help.

 

[Zeck]

My model is meshed using 3D solid elements Hex8 (Option: Laminate).

 

[aerostress82]

If you would happen to have a Hex8 layer for each ply, you can actually get the top/bottom face and mid-plane stresses to check this. As it is a combined equation of all stresses on an element, you'll need to customize your solution on these stress outputs. Once you can figure a way of using your Tsai-Wu criteria in a Patran parametric result post-processing, you should be done.

It is a really good workout though. And it should be easy to achieve it if you spend some time on it. I don't have Patran right now, that's why I can't look into this for you currently. But your solution is hidden in Patran parametric equations in "Results" module..

Spaceship!!
Aerospace Engineer, M.Sc. / Aircraft Stress Engineer

 

[VN1981]

Hi,
I hope this is gonna be of help to you. I want you to take a look at this presentation. Once you register, the link to download the presentation pdf becomes active.

http://appliedcax.com/resources-and...technical-seminar-composite-laminate-modeling

Although the folks use FEMAP, there is a short example of modeling & post-processing of a laminate using 3D Solid elements. In one of the contour plots, the max principal stress is displayed and the corresponding ply is shown. Most of the output vectors format in Femap and Patran are similar if not the same. So if you have entered all the material allowables in Patran for 3D, then you should get Failure Indices and reviewing results ply by ply, you can determine which ply has failed.

If I find some time tomorrow, I will fire up Patran and find out if Patran is capable of displaying ply-ply results for a solid laminate.