On the implementation of elasto-plastic boundary element analysis

This paper discusses efficient methods for implementing elasto-plastic boundary element programs. A solution strategy based on minimizing the number of computer operations for each iteration of the elasto-plastic algorithm is described for both the direct and indirect formulations. Interior strains may be computed from the integral equations but this is shown to be an order of magnitude greater in terms of operations (excluding evaluation of the kernel functions) than obtaining strains using a finite difference procedure. Cells existing for the volume integrations associated with the initial stress terms may be used for the differencing process. The assumption of constant stress across cells has been used and found adequate for many problems but a linear variation, with stresses being computed at cell nodes, may prove better in certain cases. All integrations must be performed numerically. A simplified flow chart of the algorithm is presented and typical solutions for two test problems are given. Finally a comparison between finite element and boundary element solution times for several problems is attempted, it seems that solution times are similar.