Natural frequencies of symmetrically laminated rectangular plates with free edges

This paper is concerned with the estimation of natural frequencies of undamaged laminated rectangular plates having completely free edges. A possible application of the result is use as a reference in the determination of location and extent of defects in laminated plates from measurements of natural frequencies of damaged plates. The Rayleigh-Ritz energy approach is employed here to obtain the approximate natural frequencies of symmetrically laminated plates. The plates are considered to be thin and to undergo small deflections, satisfying Kirchhoff's hypothesis. A complete power series is used as admissible functions for in-plane and out-of-plane displacements. In the numerical examples the accuracy of the present results is compared with experimental and finite element analysis results. The effects of aspect ratio and fiber orientation on the natural frequencies of symmetrically laminated plates are documented. For each frequency, the associated mode shape is identified and tabulated in this paper.