FINITE-ELEMENT METHOD FOR NONLINEAR FREE-VIBRATIONS OF COMPOSITE PLATES

A multimode time-domain modal formulation based on the finite element method for large-amplitude free vibration of thin composite plates is presented. Accurate frequency-maximum deflection relations can be pred icted for the fundamental and the higher nonlinear modes, A modal part icipation is defined, and accurate and convergent frequencies can be d etermined with minimum number of linear modes. A procedure for the sel ection of initial conditions for periodic plate response is presented. Convergence of frequency with gridwork refinement and number of linea r modes is studied. The classical single-mode elliptic function freque ncy solutions for simply supported beams and square plates are assesse d. Examples of orthotropic and composite plates are given, and the cha racteristics of nonlinear response are studied.