Postbuckling analysis and imperfection sensitivity of general shells by the finite element method

Buckling and imperfection sensitivity are the primary considerations in ana lysis and design of thin shell structures. The objective here is to develop accurate and efficient capabilities to predict the postbuckling behavior o f shells, including imperfection sensitivity. The approach used is based on the Lyapunov-Schmidt-Koiter (LSK) decomposition and asymptotic expansion i n conjunction with the, finite element method, This LSK formulation for she lls is derived and implemented in a finite element code, The method is appl ied to cylindrical and spherical shells. Cases of linear and nonlinear preb uckling behavior, coincident as well as non-coincident buckling modes, and modal interactions are studied. The results from the asymptotic analysis ar e compared to exact solutions obtained by numerically tracking the bifurcat ed equilibrium branches. The accuracy of the LSK asymptotic technique, its range of validity, and its limitations are illustrated. (C) 1999 Elsevier S cience Ltd. AIL rights reserved.