Influence of a supersonic flowfield on the elastic stability of cylindrical shells

Abstract

The rather complex interaction problem of shell divergence and panel flutter that may be encountered by an aerospace vehicle during the boost phase of a trajectory is treated theoretically and the results then compared qualitatively with recent experimental observations. The analytical model considers the combined influence of internal pressure and axial compressive loading on a thin-walled cylindrical shell in a supersonic flowfield. Radial edge constraint and initial imperfections also are considered. The formulation employs the nonlinear Donnell shell equations and a linear piston theory aerodynamic approximation and utilizes a kinetic stability approach. The aeroelastic stability of the shell is determined about its deformed middle surface using Galerkin's technique in a modal solution. The results of the analysis indicate that the supersonic flowfield has no effect on the critical buckling load or the unstable mode of the shell. Small amounts of axial loading, however, were found to reduce significantly the critical panel flutter speed of the shell. These results were verified, at least qualitatively, in recent wind-tunnel tests on shell models.