EFFECT OF BOUNDARY CONSTRAINT ON THE FREQUENCY-RESPONSE OF MODERATELYTHICK FLAT LAMINATED PANELS

A boundary-discontinuous Fourier-type solution to the problem of free vibration of arbitrarily laminated moderately thick rectangular plates , subjected to general admissible boundary conditions, is presented. T he YNS (Yang-Norris-Stavsky) theory incorporating first-order shear de formation, and rotary and in-plane inertias, is used in the formulatio n, resulting in a system of five highly coupled linear second-order pa rtial differential equations (PDEs) with constant coefficients. For th e purpose of illustration, the SS1 and C4 boundary conditions are sele cted here because they provide the upper and lower bounds for elastica lly supported flat panels used in helicopter rotor blades, aircraft wi ngs and other applications. Numerical results presented here include ( i) comparison with the corresponding available FSDT-based boundary-con tinuous displacement-type Fourier and Galerkin solutions, and (ii) stu dy of the effects of thickness, aspect ratio and fiber orientation ang le on the normalized natural frequencies.