Response of composite cylindrical Shells to high frequency acoustic Excitation using statistical energy Analysis

Abstract

newline Aerospace structures employ high specific strength and specific stiffness based design for which composite material is the prime choice. In many applications they are of honeycomb sandwich construction with composite face sheets. These structures experience high frequency acoustic and shock loads during the launch. For a reliable design of these elements to high frequency dynamic excitation, it is necessary to have a theoretical prediction model, in the absence of which one has to rely on the acoustic test which needs a hardware. Behaviour of the structures in the high frequency region is characterised by the higher order modes. Conventional methods are adequate to predict the behaviour in the lower order modes but they have very little applicability in estimating the responses in high frequency region. Energy based methods are reported to be viable alternatives. Among them Statistical Energy Analysis (SEA) is the widely used technique. Composite cylindrical shell is an essential part of spacecraft and launch vehicle structures. Though the methodology of estimating the response using SEA exists, its applications to composite cylindrical shells are seldom reported. Therefore, the aim of this research work is to study the dynamic response behaviour of composite cylinders in spacecraft structures using SEA. Diffused acoustic field is the dynamic load. In SEA, modal density, coupling loss factor and dissipation loss factor are the parameters, called SEA parameters, that are required to form the governing equations. The accuracy of the estimated response depends on the accuracy with which the SEA parameters are determined. The SEA parameters of composite cylindrical shells are not reported in literature. In this work, the SEA parameters of composite cylindrical shells are derived analytically and validated through experiments. newline newline