Amir Hossein Modaress-Aval - Amirkabir University of Technology, Tehran, Iran.
Firooz Bakhtiari-Nejad - Amirkabir University of Technology, Tehran, Iran.
Hamidreza Rostami - Amirkabir University of Technology, Tehran, Iran.
Earl H. Dowell - Duke University, Durham, NC, USA.

In the present study, the vibration problem of rectangular cantilever plates with varying aspect ratio has been investigated by using the classical plate theories based on the Kirchhoff hypoth-esis. Rayleigh-Ritz method has been adopted for discretization of the problem and using La-grange equations, the mass and the stiffness matrices have been derived. Using different num-bers of structural mode shapes, the convergence of the results has been shown. The theoretical results have been evaluated by using the experimental data obtained from ground vibration experiment carried out at Duke University. It has been shown that for a relatively low aspect ratio rectangular cantilever plate, by using some techniques in Rayleigh–Ritz method lead to an improvement of the results for the natural frequencies. This technique end up having two sets of decoupled equations obtained from the classical plate theory and consequently, the number of equations which have to be solved simultaneously is divided by two. This could lead to a reduction of computational time significantly.

Free vibration, Rayleigh-Ritz method, Rectangular cantilever plates, Classical plate theory