Discussion Forum

See https://www.comsol.com/forum/thread/37691/about-fixed-constraint

Best,

Jeff

I see the link.

In comsol I can not constrain the rotation of point. so the point is free is that right?

and I have one more question. In 2D solid mechanics module, there is prescribed point displacement opition. but i want to apply the initial point displacement. how can I apply initial displacement?

Thank you

Hi,

Whether or not you can constrain the rotation of a point depends on which physics interface you are using. In Solid Mechanics you cannot, since that interface only has translational degrees of freedom. In Beam and Shell you can, since there are both translational and rotational degrees of freedom.

You also have the Rigid Connector feature in Solid Mechanics. There you can prescribe the rotation at a point. But that point is attached to a whole boundary, which then behaves as a rigid body in terms of rotation.

Initial displacements (given in the Initial Values node) are only relevant as initial conditions for time dependent dynamics analysis. Initial values can only be given at the domain level, since an initial value at a point would be something highly singular (as all neighboring nodes in the mesh would have the value zero).

Regards,
Henrik

Hi,

Whether or not you can constrain the rotation of a point depends on which physics interface you are using. In Solid Mechanics you cannot, since that interface only has translational degrees of freedom. In Beam and Shell you can, since there are both translational and rotational degrees of freedom.

You also have the Rigid Connector feature in Solid Mechanics. There you can prescribe the rotation at a point. But that point is attached to a whole boundary, which then behaves as a rigid body in terms of rotation.

Initial displacements (given in the Initial Values node) are only relevant as initial conditions for time dependent dynamics analysis. Initial values can only be given at the domain level, since an initial value at a point would be something highly singular (as all neighboring nodes in the mesh would have the value zero).

Regards,
Henrik

Thank you for you reply.

can I ask more?

first, if is apply the prescribed displacement to make initial displacement, is that possible to use prescribed displacement as initial displacement? after then I move the jig by using prescribed displacement.

and second, At initial value node, I can apply initial displacement and velocity. is this domain is free from rotation?

Thank you