NONLINEAR FLUTTER OF A BUCKLED SHEAR-DEFORMABLE COMPOSITE PANEL IN A HIGH-SUPERSONIC FLOW

The non-linear dynamic behavior of a uniformly compressed, composite p anel subjected to non-linear aerodynamic loading due to a high-superso nic co-planar flow is analyzed. The effects of in-plane edge restraint s, small initial geometric imperfections, transverse shear deformation , and transverse normal stress are considered in the structural model which satisfies the traction-free condition on the panel faces. The pa nel flutter equations, derived via Galerkin's Method, are solved using Arclength Continuation for the static solution and a predictor-correc tor type Shooting Technique to obtain periodic solutions and their bif urcations. The possibility of hard flutter is demonstrated when consid ering non-linear aerodynamics. Furthermore, edge compression could yie ld multiple buckled states or coexistence of multiple periodic solutio ns with the stable static solution, that is, the panel could either re main buckled or flutter. Edge restraints normal to the Row appear to s tabilize the panel, whereas those parallel to the flow may result in a buckled-flutter-buckled transition. Quasi-periodic and chaotic motion s and associated Lyapunov exponents are also obtained. For perfect pan els, results obtained by the Shooting Technique and the Method of Mult iple Scales are in agreement only within the immediate post-flutter re gime. Results indicate that a shear deformation theory is required for moderately thick composite panels.