For solid models, every face that is coincident with a plane of symmetry should be prevented from moving in its normal direction. The Symmetry restraint type applies this condition automatically to all selected faces. The planes of symmetry should be orthogonal to each other.
Symmetry requires that geometry, restraints, loads, and material properties are symmetrical. In general, using symmetry is not recommended for buckling and frequency studies.
The following are some examples of models that are symmetric with respect to one or more planes.