Rotation around axis

mdsimulationgroup

Hi,

I'm trying to make this cube rotate about the x-axis with a moment and pinned supports but I'm guessing my constraints are not enough because the cube is going sideways.

Any ideas?

Thanks,
Frank

Victor

You're right, it doesn't have sufficient constraints.

Beware that the pinned support only pins one point even if you apply it to two nodes. If you want two pinned supports, either use two of them or 3 displacement constraints on two nodes.

There's also no constraint to react the applied moment. You can't do static analysis of a cube rotating freely under a moment load because it's not in static equilibrium. Maybe fix the opposite face, or use nonlinear dynamic response. It depends what you're trying to model.

mdsimulationgroup

Hello,

The attached liml works to cause a rotation around the x-axis. However, I do not want to use a moment. I would like to be able to set rotation based on angle because I need to have a set RPM. "Node Rotation" is only for beams and shells. How can I set up a rotation similar to "Node Rotation"?

Thanks,
Frank

Victor

You can use Node-surface coupling for that.

mdsimulationgroup

Thanks Victor, right after I posted the previous comment, I figured out the node-surface coupling and ended up with the same solution as yours

Another question, with the node rotation, are you unable to put a displacement on the node? I am trying to model a piece being wrapped around a bar.

Victor

You can't have a time-dependent displacement on the same node as the time-dependent rotation. That's a limitation of Mecway. You also can't have constraints on the surface of node-surface coupling, which is a limitation of CCX.

A workaround is to extrude a thin layer that doesn't have the X displacement constraints.

mdsimulationgroup

Awesome! That works perfectly!