Free vibrations of the clamped circular laminated plates containing multiple disk-shaped delaminations of a same size are analyzed on the basis of the theory of small deflection of plates. Analysis of a model assuming the contact of the two crack faces is presented. For non-axially symmetric vibrations, the equations of motion are solved by neglecting the in-plane displacements of the reference-surface and by modeling the crack part as two lapped discs hinged at the edge. Axisymmetric free vibrations are studied by taking account of the radial in-plane displacement of the reference-surface. Analyses and experiments are carried out for the natural frequencies. It is shown that the effect of the in-plane displacements of the reference-surface on the free vibration characteristics of laminated plates is very small.
