Flutter analysis of composite panels using high-precision finite elements

Abstract

A high-precision 18-degree-of-freedom triangular thin plate finite element procedure is presented for studying the panel flutter of composite thin plates. Classical lamination theory, together with linearized piston theory, is used to study the effects of aerodynamic damping, boundary constraint, flow orientation, composite filament angle, and orthotropic modulus ratio on the flutter characteristics of both isotropic and composite panels. The numerical results indicate that aerodynamic damping, which enlarges the flutter boundary, is generally beneficial. The panels with stronger structural boundary constraint possess a better capacity to resist flutter instability. Alignment of the composite filament and flow orientations results in the best flutter performance for both fully simply supported and fully clamped panels, whereas alternative flutter-divergence type instability, which is not observed in the isotropic cases, takes place as the composite filament angle varies in the cases of cantilevered panels. The orthotropic modulus ratio is shown to be very effective in enlarging the flutter boundary; however, a reverse trend may occur if the instability type is changed from flutter to divergence. Substantial improvement or even complete avoidance of flutter can be attained if the composite panel is properly tailored.