Finite element time domain - Modal formulation for nonlinear flutter of composite panels

Abstract

A finite element time domain modal approach is presented for determining the nonlinear flutter characteristics of composite panels at elevated temperatures. The von Karman large-deflection strain-displacement relations, quasisteady first-order piston theory aerodynamics, and quasisteady thermal stress theory are used to formulate the nonlinear panel 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 obtained through a modal transformation and reduction. All five types of panel behavior-flat, buckled, limit-cycle, periodic, and chaotic motions-can be determined