15 March 2018
- Last edited 15 March 2018
Warning messages like these are often of no consequence to the solution.
If your solution has small deformations, you could turn off Large Deflection under Analysis Settings, solve and get the same results without the warning.
An example of a support that can become invalid under large deformation is a compression only support, which is a quick and easy way to add frictionless contact to a model without manually creating another face. ANSYS automatically makes a copy of a selected face of the model to become a fixed rigid surface. The selected face of the model has frictionless contact elements to the invisible rigid surface. However, if the model has a significant lateral motion on the rigid surface, nodes can "fall off" the surface and the support becomes "invalid" because the user probably did not want that to happen.
The second warning is very common and very often understood as acceptable. If the lower body has contact elements on the top edge, and a displacement BC on the left or right side, the node in the corner has both, which generates the warning. It is possible (but unnecessary) to eliminate the warning by applying the displacement BC to all the nodes on the edge except for the corner node, which eliminates it from having two masters. In fact, there is no conflict in what the solution is asking that node to do, it can do both.
It is possible to add incompatible BCs to a model, and that is when the warning should be heeded and corrective action taken. For example if a Fixed support is added to the bottom face, and a displacement BC added to an adjacent face, nodes on the common edge can't both move and not move at the same time.