Free vibration of unidirectional sandwich panels, Part II: Incompressible core

The free vibration response of a unidirectional sandwich panel with an incompressible core using shear deformable and layered models is presented. The models considered include the layered model, ordinary sandwich panel theory that uses a zig-zag in-plane displacements distribution in addition to the shear deformations and the first and high-order shear deformable theories that adopt an approach which replaces the layered sandwich panel with a single layer with equivalent properties. The mathematical formulations use Hamilton's principle to present the general equations of motion and the specific mass and stiffness matrices for a simply-supported panel. The results of the models are compared with the closed-form solution of the 2D elasticity equations of motion and finite element results of ADINA. The numerical comparison is described in terms of eigenfrequencies and eigenmodes of displacements and stresses and reveal a good correlation at the lower modes only.