Incremental elastoplastic analysis for active macro-zones

In this paper a strategy to perform incremental elastoplastic analysis using the symmetric Galerkin boundaryelement method for multidomain type problems is shown. The discretization of the body is performedthrough substructures, distinguishing the bem-elements characterizing the so-called active macro-zones,where the plastic consistency condition may be violated, and the macro-elements having elastic behaviouronly. Incremental analysis uses the well-known concept of self-equilibrium stress field here shown in adiscrete form through the introduction of the influence matrix (self-stress matrix). The nonlinear analysisdoes not use updating of the elastic response inside each plastic loop, but at the end of the load incrementonly. This is possible by using the self-stress matrix, both, in the predictor phase, for computing the stresscaused by the stored plastic strains, and, in the corrector phase, for solving a nonlinear global system, whichprovides the elastoplastic solution of the active macro-zones. The use of active macro-zones gives rise toa nonlocal and path-independent approach, which is characterized by a notable reduction of the number ofplastic iterations. The proposed strategy shows several computational advantages as shown by the results ofsome numerical tests, reported at the end of this paper. These tests were performed using the Karnak.sGbemcode, in which the present procedure was introduced as an additional module.