Failure Criteria Outputs

General Questions
1

Hi, how can I enable composite failure criteria in the Field Outputs?

Either Tsai-Wu Criterion or Hashin Criterion. I would like to examine the failure mode in each ply.

I have tried adding *FAILURE CRITERION, TYPE=HASHIN under my material properties but it doesn’t work.

2

This is not even Abaqus keyword (it should be *DAMAGE INITIATION, CRITERION=HASHIN/TSAIWU or *FAIL STRESS) but CalculiX doesn’t support those criteria anyway. Here’s a full list of the keywords supported by CalculiX: https://www.dhondt.de/ccx_2.22.pdf#page.6

Since there are no such failure criteria in PrePoMax and CalculiX, you could try computing them in postprocessing with the new Create Field Output → Equation tool or in ParaView.

3

Available through this fork of PrePoMax:

3 Likes
4

just look up example input menus, it’s really interesting and perhaps will be merge and publish in next development versions. Thank you.

shell_composite
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in addition, CalculiX composite shell may not good in several conditions, and it could be useful to have button menus to convert to solid element. Each layer is separated parts and coincident nodes connected by equal displacement constraint to avoid averaging in stress results.

1 Like
5

As a workaround, I guess prepomax can already extrude shell mesh using ‘check model’ tool (using applied thicknesses).We could then export it as INP and import the volumic mesh back. I am just concerned if nodes will be condensed or not. But there is another tool to merge coincident nodes automatically. Never tried yet. I am pretty sure it will not catch the variable thicknesses from shell sections, but should work for constant thickness laminates. I will see to integrate the 2D to 3D conversion in my fork. Thanks.

6

There are multiple ways to get solid element layers:

  • with the built-in Thicken Shell Mesh tool (but it supports only constant thickness)
  • with the Multi-layered option of the Extrude and Revolve tool (but it operates on solid geometry) - this supports different numbers of elements per layer and different relative element sizes
  • with CalculiX’s internal expansion of shells (also composite ones) to solids - as you said, you can use the Check Model option instead of running an analysis, but layers indeed become separate solid parts and need to be connected manually