FINITE-ELEMENT TIME-DOMAIN - MODAL FORMULATION FOR NONLINEAR FLUTTER OF COMPOSITE PANELS

A finite element time domain modal approach is presented for determini ng the nonlinear flutter characteristics of composite panels at elevat ed temperatures. The von Karman large-deflection strain-displacement r elations, quasisteady first-order piston theory aerodynamics, and quas isteady thermal stress theory are used to formulate the nonlinear pane l flutter finite element equations of motion in nodal displacements. A set of nonlinear modal equations of motion of much smaller degrees of freedom for the facilitation in time numerical integration is then ob tained through a modal transformation and reduction. All five types of panel behavior-flat, buckled, limit-cycle, periodic, and chaotic moti ons-can be determined. Examples show the accuracy, convergence, and ve rsatility of the present approach.