Dynamic response of composite sandwich plates subjected to initial stresses

The transient response of composite sandwich plates under initial stresses is investigated using a new finite element formulation. An assumed strain nine node shear deformable plate bending element with nine degrees of freedom per node is formulated based on a refined higher order theory. The higher order theory contains in-plane displacements that are expanded to include the higher order terms in the Taylor series expansion as a result of which there is no need for shear correction factors. The popular assumed strain concept is used to ensure that the developed nine node element passes the patch test and shows no signs of shear locking and spurious zero energy modes in the present finite element formulation. The Newmark time integration algorithm is used to solve the time dependent equations of the plate. Numerical results are presented to show the effects of initial stresses on deflection and stresses of composite sandwich plates.