Why does the holding plate move unexpectedly in CNTNLSUB, even with SPCs applied?

diogo_leiras
diogo_leiras Altair Community Member
in Community Q&A

I have a transient nonlinear analysis in OptiStruct with two subcases to analyze (subcase 2 is a CNTNLSUB relative to subcase 1). In the first subcase, a holding plate engages with the rubber teeth to geometrically position them in their final location, having in consideration their final stress state (which is important for the CNTNLSUB). Consequently, in subcase 2, a punch presses down on the top of the rubber, and the holding plate's purpose is to remain in place so the rubber can be pressed against it.

During subcase 1, the holding plate has an enforced displacement applied until it reaches its final position. The objective is for it to stay static and fixed in its six degrees of freedom in subcase 2.

subcase_1.avi


However, when subcase 2 begins and the punch presses down on the rubber from above, the holding plate starts moving in the opposite direction, returning, gradually, to its initial position (before subcase 1).

subcase_2.mp4

The issue I’m facing is that I already have an SPC applied to the nodes of the holding plate in the SPC load collector associated with subcase 2, so this behavior doesn’t make sense. What could be causing this to happen? I’d appreciate any help!

P.S: I’ve attached a first video showing subcase 1 and a second video where the holding plate in subcase 2 can be seen moving (unexpectedly).

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Answers

  • Rajashri_Saha
    Rajashri_Saha
    Altair Employee

    Please verify the SPC applied to the holding plate in 2nd subcase. Have you done this by MODCHG?

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