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

The non-linear dynamic behavior of a uniformly compressed, composite panel subjected to non-linear aerodynamic loading due to a high-supersonic co-planar flow is analyzed. The effects of in-plane edge restraints, 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 panel flutter equations, derived via Galerkin's Method, are solved using Arclength Continuation for the static solution and a predictor-corrector type Shooting Technique to obtain periodic solutions and their bifurcations. The possibility of hard flutter is demonstrated when considering non-linear aerodynamics. Furthermore, edge compression could yield multiple buckled states or coexistence of multiple periodic solutions with the stable static solution, that is, the panel could either remain buckled or flutter. Edge restraints normal to the Row appear to stabilize the panel, whereas those parallel to the flow may result in a buckled-flutter-buckled transition. Quasi-periodic and chaotic motions and associated Lyapunov exponents are also obtained. For perfect panels, results obtained by the Shooting Technique and the Method of Multiple Scales are in agreement only within the immediate post-flutter regime. Results indicate that a shear deformation theory is required for moderately thick composite panels.