A study of wave propagation in thick/multilayer panels using theory of elasticity

Light weight multifunctional and multilayer panels are being considered as an alternative to traditional panels used in the design of aerospace vehicles. However, for design and development of future aircraft sidewall panels with reliable acoustic performance, it is necessary to understand the fundamental wave propagation modes (i.e., bending, shear, extension, and through-thickness breathing/dilatation) in the panel material system at the design stage. Thin and thick plate theories capture bending, shear (approximately), and extension in the panel, but fail to capture the dilatation motion, which is significant in sandwich plates with soft core material. In this paper, we present a generalized approach based on theory of elasticity for analyzing the wave propagation in thick and multilayered plates. The theory can be used to discover and calculate all wave modes and plot detailed dispersion diagrams. Furthermore, a strain energy based metric is presented for quantifying the relative contribution of extension/bending, shear, and dilatation in a wave mode of interest. The analysis is thus ideally suited for use in the vibroacoustic design of future multilayered sandwich plates.