Flutter analysis of flat rectangular anisotropic panels in a high Mach number supersonic flow

Abstract

A study of the flutter of a flat, simply supported, rectangular, anisotropic panel, exposed to supersonic flow on one side, is carried out using small deflection thin-plate theory and two-dimensional piston theory aerodynamics. The effect on flutter of the following items are examined: individual orthotropic ply orientation with respect to the freestream; inplane compressive stresses in the streamwise direction; aerodynamic and/or structural damping; and the number of layers in an angle-ply panel, with plies of the same orientation angle but alternating signs. Solutions are obtained using a twenty term Rayleigh-Ritz procedure. Three different fiber-matrix combinations for the individual orthotropic plies are used, These are: boron-epoxy, graphite-epoxy and boron-aluminium. The results indicate that the parallel alignment of the ply principal axis with the freestream direction does not necessarily raise the flutter boundary. The flutter value is dependent on the relative stiffnesses of the individual plies, their orientation with respect to the freestream, and the panel aspect ratio. Increasing the number of plies in the panel and the addition of inplane compressive stresses lowers the flutter boundary while the addition of damping always raises it.