A LOCAL-GLOBAL MODEL FOR THE NONLINEAR-ANALYSIS OF LOCALLY DEFECTIVE SHELLS OF REVOLUTION

In this paper a local-global analysis technique is presented for the n on-linear analysis of shells of revolution with a localized material d iscontinuity in the form of a crack or a cutout. The local zone is mod elled using two-dimensional general shell elements. Axisymmetric shell elements with Fourier description in the circumferential direction ar e used away from this local zone. In contrast to the earlier work of t he authors, the geometric non-linearity is taken into account in the a xisymmetric zone as well. The harmonic coupling in the axisymmetric zo ne is efficiently handled through the pseudo-load approach. A special preconditioned conjugate gradient iterative method is employed in conj unction with the are length method for achieving improved convergence and negotiating the limit points. The attractive features of this meth odology are that the tangential stiffness matrix of the structure is n ever assembled and factorized and that most of the computations are si mple matrix-vector multiplications which are carried out efficiently a t the element level. Numerical examples are presented to demonstrate t he applicability of this method.