Description:
An expression is obtained from which the natural frequencies of a rectangular orthotropic plate, under any combination of boundary conditions of simply supported, elastically supported, or clamped. The Mindlin-Timoshenko theory, which includes the effects of transverse shear and rotary inertia, is used to describe the plate motion. The solution is obtained with an extension of the Galerkin procedure previously developed, in part, by the author. Comparison of results with the limited results of previous investigations is excellent. Numerous data are presented for the lowest natural frequencies of rectangular and square plates for boundary conditions on all four edges that vary continuously from simply supported to clamped, and for various combinations of length-to-thickness ratios.