Learning Forum

[duchm19]

Hello,

I encountered a problem when using submodeling and cyclic symmetry in a transient structural model. The cut boundary constraint was applied on the symmetry plane (see figures below), resulting in an artificial stress. 

 

I wonder if anyone has any ideas for this case.

Thanks in advance.

[mjmiddle]

When you make a submodel you have to apply all the loads and supports (all boundary conditions) on the submodel exaclty as they were applied on the full model, for any faces that remain in the submodel, used for BC selections. This includes the cyclic symmetry you set up, and the rotational velocity and whatever supports you had used in the full model. You probably set up some support on the faces near the axis of rotation.

You may have applied a pressure on the blades, and if the edge of those selected faces for the pressure load lie on the cut boundary faces, then you can't define a pressure on those nodes that are on that edge in the submodel.

In addition, the cut faces for the submodel should be away from any high stress gradients, and I think it's typical to have high stresses at the blade roots. It looks like your submodel cut faces are at the blade roots.