On the elastodynamic response of thick multilayered plates subjected to impact loads

The transient axisymmetric response of thick multilayered plates is considered from a dynamic elasticity point of view. The analysis is based on an exact elasticity formulation and analytical solution, via eigenfunction expansion, for a plate comprised of an arbitrary number of perfectly bonded isotropic layers of arbitrarily differing thicknesses and material properties. Results of numerical simulations based on the exact solution are presented for a single layer plate, for sandwich plates and for bilaminates with a central "adhesive" layer. In each case, frequency spectra and physical through the thickness depictions of selected individual elastodynamic modes representative of the various branches of the spectrum are computed and compared. A forcing function is formulated to simulate transverse impact and results corresponding to both "long" and "short" duration normal impact of each structure are presented in the form of physical depictions of the entire deformed cross-section of the structure as a function of time. In addition, the degree of participation of the various modes for the transient response is monitored by a scaled shade intensity of the frequency spectrum plot. The dimensions of the impactor considered are on the order of the overall thickness of the plate, and the responses are seen to capture the critical wave behavior in the vicinity of the impactor. (C) 1998 Academic Press Limited.