Learning Forum

[R421]

"I'm working with an ANSYS shell model and need assistance with constraints. Is it possible to apply a constraint in the +y direction while allowing release in the -y direction? Additionally, is there a way to incorporate a friction coefficient in this setup? Any guidance on achieving this in ANSYS would be greatly appreciated."

[peteroznewman]

One way to allow free motion in one direction and prevent motion in the opposite direction is to add nonlinear contact.  Frictional or frictionless contact requires that you add an extra body.

For a solid block that will experience only small motions, you can avoid manually adding the extra body by using a Compression Only Support scoped to one face of the block. Ansys will automatically create an extra body (under-the-hood) by copying the face and creating frictionless support to provide that functionality. However for large motions, nodes in the block will fall off the surface that was created so it is generally better to manually create a surface larger than the face to accomodate large motions.

When you define Frictional contact, you can add a coefficient of friction.

[R421]

 

Thank you for the reply.

what do you mean by small motions and large motion?

I had model a solid body below the shell. The body is fixed and the contact between the body and shell is frictional.

Does this frictional contact resisit the motion in Y-direction?

I also have a zero displacement support at bottom along Z-dierction.

Is that correct?

 

[peteroznewman]

Yes. Frictional contact between the block face and shell edge will allow the block to prevent -y movement while allowing separation in the +y direction. The Z = 0 BC will prevent the edge from falling off the block in the Z direction. Another constraint prevents large movement in the X direction. Large movement is when nodes fall off the Contact surface.

If the force has a component in the -y direction then the model can solve. If the force has a +y component then the model can't solve it there is no constraint in that direction. 

[R421]

thank you for your help.