problem with rigid body motion 1

[ndrssenjaya]

Hi, I'm new to ANSYS. I am trying to built up a model with support definition like it is shown in the attachment. The idea is to bend a wire to a designated bent radius with frictional contact involved between wire and the target tubular surface.
The popped up problem is always about rigid body motion so I think the problem must be on the support definition. could anybody help? thank you in advance.

 

[FEA way]

Are these two parts already in contact at the beginning of the analysis ? Without such connection they are underconstrained. Try running modal analysis to see what happens. I also advise using prescribed displacement instead of force if possible.

 

[ndrssenjaya]

hi, thanks for the insight. it has initial gap of about 5 mm, so it is not contact initially. I'm trying to investigate the capacity of the wire bended in a specific radius, so I put the force to see how much it cant endure before failure. Could you please tell me specifically how to run modal analysis in ANSYS? I really am blind in using this program. thank you again.

 

[FEA way]

Then you should make the parts contact at the beginning of the analysis to eliminate RBMs occuring before contact initializes. Or use inertia relief to stabilize the model until both parts contact each other.

To run modal analysis in ANSYS follow these steps:
- select Modal analysis type
- add geometry and mesh as well as materials (density is needed for this type of simulation)
- in Analysis Settings specify the requested number of modes (10 should be enough)
- define linear (bonded) contact between parts and make sure that they are initially in contact (otherwise you will get rigid body modes for both parts - the analysis will complete but these modes are not what you are looking for)
- add boundary conditions from static analysis but remove the load (forces aren’t take into account in such analysis)
- solve
- select all modes from the bottom window, click on them with right mouse button and choose „Create Mode Shape Results”
- review the mode shapes