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[parth.shingte]

Hi all,

I am trying to simulate a forming process for PET material. I am trying to use the MAT275 material model on LS DYNA V4.10.8. When I try to simulate the process, the part with MAT275 disappears from the simulation and the simulation immediately shows normal termination. I see no error messages in the .out or messag file. If i use another material model (say MAT124) then the simulation runs correctly. I am using ELFORM 15 shell elements. (Axisymmetric Solid)

What could be the reason for this? Is it due to bad material parameter definition or is there another issue?

[Nanda]

Hi,

Your suspicion is correct. It could be something related to a bad material parameter or a complete mismatch between material parameter units and input deck units. I would narrow it down by checking for units and adjusting the parameters here and there to see if it resolves the issue.

Regards,

Nanda.

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[parth.shingte]

Hi,

I tried to change a few parameters based on the documentation, but it did not help.

I also tried using MAT256 since in the material manual there are typical material parameters provided for polycarbonate. I used those values just to check if the simulation runs normally. But even with that I see the same issue. The part disappears and the simulation shows normal termination instantly.

[Nanda]

I would do a simple tensile test with the same material model and see what happens. Even a single element cube stretched in one direction should tell us if the material parameters are at fault.

 

[parth.shingte]

Hi,

I just did a test with a single element cube with the same material model MAT275 and it works. Is there an issue with the implementation of the material model with axisymmetric solid elements (ELFORM 15)?

[Nanda]

Seems like it, but it is not mentioned in the manual, though. Does ELFORM 12 or 13 work as expected? Then we can say ELFORM 15 with MAT_275 is a limitation for now!

[parth.shingte]

It doesnt work with ELFORM 13 either, with ELFORM 14 it shows out of range velocities NaN. In the manual it is mentioned that solids and 2D continuum elements i.e. shell formulations 13, 14 ,15 are supported for MAT_275.