ERRORS IN DOUBLE SINE SERIES SOLUTIONS FOR SIMPLY SUPPORTED SYMMETRICALLY LAMINATED PLATES

The Rayleigh-Ritz method used with double sine series descriptions of transverse deflection has been applied extensively to obtain results f or simply supported symmetrically laminated composite plates. The pres ent work shows that, because of the inherent imposition of certain art ificial derivative constraints, the double sine series is not a genera lly admissible deflection function for such plates. Results are presen ted for linear bending, vibration and buckling analyses of plates in w hich through thickness shear and rotary inertia effects are negligible . The values obtained when using the double sine series are observed t o overestimate the stiffness of plates having bending-twisting couplin g. The extent of the errors possible is shown to be reasonably signifi cant and it is noted that such results might be misleading to the desi gner.