Very important meshing check for assembly of components.
Natural frequency calculations without applying any restraints /constraints.
Any single object allowed to vibrate freely, should show first 6 modes as rigid (natural frequencies = 0) and 7th onward show deformable modes with positive value of natural frequency.
Suppose there are 100 parts in the assembly, 99 are connected to each other and 1 left out due to mistake. Free-Free run of the assembly will show 6 rigid modes and by observing mode shapes one can easily detect which component is un-connected.
