Finite Element Nonlinear Random Response of Composite Panels of Arbitrary Shape to Acoustic and Thermal Loads

摘要

A finite element formulation in modal coordinates is presented for postbuckling of thin laminated composite plates subjected to combined thermal and mechanical loads. The mechanical load considered is a uniformly distributed transverse load which is to simulate the static pressure differential applied to the aircraft skin panel. A modal participation value is defined and the minimum number of modes for convergence and accurate postbuckling solution can be determined. The modal formulation reduces the number of coupled nonlinear equations in the structure nodal degrees of freedom of hundreds, if not thousands, to a number of coupled nonlinear equations in the modal coordinates of usually ten. This greatly reduces the computation costs. Deflection shape change for a long rectangular plate is observed and investigated. Three multiple postbuckling solutions or branches are obtained from the modal formulation. The total potential energy and its second variation indicate that there exist only two stable, primary and secondary branches and the third is an unstable peak.