For large problems, solid elements can often take a long time to mesh and solve. For thin bodies with constant thickness, we can replace the solid elements with shell elements which will significantly speed up the process of both meshing and solution.
For bodies which are geometrically symmetric and are loaded symmetrically about a plane, the symmetry condition can also be used to speed up the analysis. The built-in symmetry condition of SolidWorks can only be applied on faces, however when shell elements are cut on a plane, the produce symmetry about edges and not faces. The symmetry condition can then be created manually using the reference geometry condition. In applying this condition, we need to restrict any displacements along the plane of symmetry and at the same time we need to restrict the out of plane rotations. (Shell elements have 6 dof compared to solids which have only 3 dof).
The table below highlights the symmetry condition in the three principle planes.
|Symmetry Boundary ConditionsPlane of Symmetry|