VIBRATIONS OF LAMINATED COMPOSITE COMPLETELY FREE TRIANGULAR AND TRAPEZOIDAL PLATES

The first known natural frequencies for laminated composite angle-ply triangular and trapezoidal plates with completely free boundaries are presented. The Ritz method with algebraic polynomials is used. Detaile d convergence studies are made and show that relatively accurate resul ts can be obtained. Results are then obtained and listed for the lowes t eight frequencies, and for various sets of shapes including right an d symmetrical triangular and trapezoidal thin plates. The method can b e used for these plates with arbitrary shape.