Dynamic response of two-layered cylindrical shells to time-dependent loads

Abstract

A modal analysis is used to predict the response to time-dependent loads of a finite-length, simply supported elastic circular cylindrical shell composed of two bonded isotropic layers. A shell of infinite length subjected to an external load with no axial component is also analyzed. Calculations were made for the specific case of a two-layered cylindrical shell loaded impulsively by a lateral blast distributed sinusoidally around half of the circumference. It is found that, for the particular loading treated, the axial stress in the finite-length shell has a larger amplitude than the circumferential stress, even though the load has no axial component and even though the shell is not axially constrained in any way at the edges. A dynamic edge effect is seen to propagate into the shell. Use of a ring model of an infinitelength shell subjected to an axially uniform pressure pulse leads to an accurate prediction of the normal stresses at the middle of the finite shell for very early response times. However, the radial displacement response is four times as great for the ring as for the finite shell, and the fundamental frequency of the ring is a seventh of that for the finite shell. The axial stress amplitude predicted by the ring model (crx = va0) is much smaller than that predicted by the finite-length model, and of course no edge effect is possible in the ring.