Analytical solutions, based on the Ritz method, are derived for the lowest natural
frequency of rectangular symmetric angle-ply laminated plates. Since symmetric
angle-ply plates have nonzero cross-elasticity constants, the solutions are
approximate. The accuracy of these solutions is tested with a convergence
study using the Rayleigh quotient iteration method. With the solutions
available in symbolic form, parameter studies are presented that establish
the effect of plate aspect ratio and ply orientation angle for a number of
stacking geometries. The results are also verified through a comparison with
numerical Ritz solutions, showing a maximum error of 5% in our approximate
solution.