October 10, 2023 at 12:21 pmAhmetKayaSubscriber
Dear ANSYS community,
I am currently engaged in modeling a quasi-static compression analysis on structures constructed from paperboard. In my pursuit of precise design, I recognized the value of commencing with a simplified plate model to proactively identify potential errors. My material of choice is orthotropic elastic with multilinear isotropic hardening and the Hill yield criterion. I initially created the composite part using ACP and subsequently transferred the shell composite data to Static Structural, LS-DYNA, and Explicit Dynamics.
For your reference, I have included a visual representation of my workflow and a related case study in the form of an image, which can be viewed in this YouTube video: [insert link here].
However, I am encountering a significant issue in my simulation. Specifically, when I enable the multilinear isotropic hardening and Hill yield criterion in the material definition, LS-DYNA produces an error (*** Error 40724 (SOL+724) routine eigab fails to obtain eigenvalues), and Explicit Dynamics also fails with the error message stating, "Could not transfer material Sheet A 190 gsm to the solver. Error reading in the CAERep from Simulation."
Curiously, when I suppress the multilinear isotropic hardening and Hill yield criterion in the material definition, both LS-DYNA and Explicit Dynamics perform as expected without errors. I am seeking guidance to diagnose and address the root cause of this simulation problem.
Any insights or assistance from the community would be greatly appreciated.
October 12, 2023 at 12:56 amReno GenestAnsys Employee
I don't think multilinear isotropic hardening and Hill yield combined with orthotropic elasticity is supported in Explicit Dynamics and LS-DYNA. In LS-DYNA, you can open the input.k file in a text editor to check what material model that is used.
At Ansys 2023R2, there is a new orthotropic strength material model for Explicit Dynamics:
You can define orthotropic strength coefficients (A11 - A66) along with a master Stress-Plastic strain curve. See image above.
You will find more information here:
There is information on how to obtain and calculate the coefficients here:
This information is in the Composite modelling guide for Autodyn:
This model can be combined with orthotropic elasticity.
In LS-DYNA, *MAT_PAPER (*MAT_274) could be used. Here is an excerpt from the LS-DYNA User Manual Vol II:
You can download the LS-DYNA manuals here:
Note that *MAT_PAPER is not available in Ansys WB yet, but you can include it in your model using a command snippet or using the Keyword Manager. You can use *PART_COMPOSITE to build the composite layup with *MAT_PAPER using a command snippet as well.
Let me know how it goes.
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