Dynamic response of shell type structures subjected to impulsive mechanical and thermal loadings

Abstract

In order to achieve better understanding of impulsive loading effects on shell structures, a dynamic response analysis method is developed using continuous shell elements as the mathematical model. The present work is limited to the consideration of linear elastic effects. The extension to stability problems in terms of the bifurcation points of the static equilibrium, to the inelastic response, and to the postbuckled mode shape analysis based on geometric nonlinearities is being considered as the continuation of the present work. The modal approach is used for the response analysis. An original method, capable of handling large numbers of branched shells, is developed for the analysis of free vibration modes and frequencies. Hamilton's principle, suitably modified to consider the thermal effects, is employed for the analysis of the dynamic response. Static analysis (to be covered in a separate paper) for asymmetric loadings is a by-product of the present analysis. While the building blocks of the dynamic analysis are the mode shapes of free vibration of the axisymmetric shell model, the response definition is such that structural and mass non-symmetries can be included. The method as outlined here is very general in nature, and efficient for practical applications. At present it is used for the analysis of the dynamic structural response of missiles and re-entry space vehicles, and as well for the analysis of nuclear reactor vessels and internals subjected to axisymmetric time dependent thermal and mechanical loadings.