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Timo Ksr

Parts with free DOF "grow" in Result of Analysis

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Hi, 

 

I have a model with certain parts with a free degree of freedom (rotational, actually ball bearings).

 

In the static analysis it happens, that the part "grows", which obviously is wrong, and I believe the reason is that it is not constraint for every dof. 

 

How can I fix this and still keep the dof6 unconstrained? 

 

Thank you all!

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The shaft grows, it has a rotational dof. It is connected to the middle part with RBE2 and CBUSH which connects the rbe2 spiders, which has a K6 = 0 Stiffness.

 

 

2045120588_shaftsmall.JPG.ed64ab572e17cca1a74a6874c06fb4d5.JPG1261124462_Shaftbig.JPG.5009f24f5d14a19aad32a635bc4bd717.JPG

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you have to check how much of rotation you get and if this makes sense for your model and analysis type.

If the large rotations are really expected, HV in static mode doesn't "understand" rotations too large, and it shows the rotational displacement as if it was expanding.

You can take a look at transient mode animation to see the proper model rotating.

If this model is explicit, it is ok to let it free to rotate, and you just need to use 'Transient' animation. 

If it is implicit, I would make sure this rotations are controlled.

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