Bergan–Wang theory for thick plates is extended from statics to dynamics. In line
with static theory, kinematic assumptions are developed and explored that allow the
equations of motion to be expressed in terms of the transverse displacement only.
These assumptions include approximations of the shear strains in terms
of spatial and temporal derivatives of the transverse displacement, as well
as a simplification of the rotational inertia. The equations of motion are
derived systematically through variational principles. The resulting partial
differential equations are eighth-order in space and, depending on the kinematic
assumptions, can be second-, fourth- or sixth-order in time. An analysis
of dispersive flexural waves is used to compare and contrast the various
theories.