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ANSYS - Creo Simulate discrepancy

mlindqvist
12-Amethyst

ANSYS - Creo Simulate discrepancy

In  a previous discussion I presented a contact example to compare ANSYS with Creo. In that case, both results were credible, and Creo's results was somewhat more realistic, but that was with default ANSYS mesh, and no particular effort to refine mesh/convergence in either model.

I have here made a similar example, a pre-loaded bolt that clamps two parts together. The pre-load is generated with a coeff. of thermal expansion= 0.001 for the bolt, and a -1 temp load that makes the bolt contract. The aluminium plates have coeff. of thermal expansion = 0. The bolt is made of stainless steel.

The results here differ more. Creo's contact area is smaller but has higher max contact pressure. ANSYS was run with frictionless contacts and 1 and 10 in normal stiffness factor in two different runs. The ANSYS solution seem indifferent to mesh refinement, i.e. the mesh should be OK. As far as I can see, the material properties are identical. I'm not too experienced with ANSYS, so I struggle with the UI. The Creo solution (SPA, about 7000 elements) took 2+ hours, ANSYS took about 2 minutes. I also ran the Creo model as a "quick check" which was much faster, and did not change the results considerably. Creo's mesh is slightly refined compared to default mesh settings.

ANSYS max contact pressure is about 8 MPa, Creo: 14 MPa.

Which solution is correct?

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ACCEPTED SOLUTION

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I found the error! The contacts between bolt heads and plates were "bonded" in the Creo model. With frictionless contacts, the results are more or less idenetical with the ANSYS model. A bit surprising that such a seemingly small difference in the model can produce a significant difference in results. Since neither "bonded" nor "frictionless" contacts in this case.represents reality, the correct results should be somewhere between these solutions.

Best regards...

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1 REPLY 1

I found the error! The contacts between bolt heads and plates were "bonded" in the Creo model. With frictionless contacts, the results are more or less idenetical with the ANSYS model. A bit surprising that such a seemingly small difference in the model can produce a significant difference in results. Since neither "bonded" nor "frictionless" contacts in this case.represents reality, the correct results should be somewhere between these solutions.

Best regards...

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