Learning Forum

[YX_trick]

When I was simulating a shell-solid contact problem with ANSYS. That is a thermal expasion task, which a surface(shell) contacting with a volume(solid). The friction coeffcient was set as 0.1 or 0.01. The bottom volume is totally fixed, while the surface is only supported by the volume. And gravity, temperature is applied on the surface. It kept bring me errors like "An extremely large pivot ratio has been detected by the sparse solver. This usually indicates a very ill-conditioned matrix or possibly rigid-body motion. The solution may be inaccurate or even erroneous. Please check your results carefully", "element has excessive distortion" or "element has excessive thickness change" since I was simulating a hyperelastic material.

However, the contact element I have used is CONTA174. To solve the rigid body problem, I tried everything with KEYOPT(5), (9) and (15), while it didn't improve a lot. Since I am simulating shell element, I also turned the thickness effect on , which is KEYOPT(11),1.

Meanwhile, I need to do a lot of simulations with different material assigned to the shell element in my project. I found that sometimes the simulation can give me a good result under case 1, it might show the errors mentioned above when I changed the material to another case. I want to achieve a universal command and solution.

[YX_trick]

This is the error message.

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And here is the simulation results. Successful one on the top and unsuccessful one on the bottom. By the way , sometime the unsuccessful simulation just exploded.