A discrete element procedure for thin-shell instability analysis.

The concepts of the matrix displacement approach to discrete element structural analysis are extended to predict general instability. Instability phenomena are accounted for by considering the influence of element membrane forces on element effective flexure stiffnesses. Particular attention is given to the problem of determining membrane force distributions that account for interelement membrane-flexure coupling. Representations of instability effects are formulated for several levels of approximation for an arbitrary quadrilateral plate element. Critical applied load intensities are predicted for plate, arch, and spherical cap structures to demonstrate convergence characteristics and to provide comparisons with test data and classical solutions.