Deepesh, it would be helpful if you show your particular geometry.
If you use shared topology between a surface and a solid, the common face or edge will share nodes. If the common edge is a straight line of the surface on the face or edge of a solid, there will be shared nodes along that line, but the solid elements have no rotational stiffness to support the shell elements. The model will have a hinge, also called a mechanism, which can often cause the Static Structural model to fail to solve. If you don't want a hinge you have two choices: 1) Use Bonded Contact and select an area on the solid to bond to the edge of the surface or 2) Extend the surface so that it shares an area on the face of the solid, which will provide a way to support the moment on the straight edge that was a hinge in the original Shared Topology configuration.
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