ENHANCED VISUALIZATION OF FAILURE MECHANISMS BY FINITE-ELEMENTS

The finite element method, in conjunction with elasto-plastic constitu tive laws, is able to give accurate estimates of collapse loads in geo technical problems. The mechanisms of failure produced by these analys es, however, are often diffuse and poorly defined, as compared with th ose assumed in classical limit analysis techniques. This paper describ es two methods for improving their visualization. It is shown that by introducing a small degree of post-peak material softening into the co nstitutive law, a considerably more localized mechanism is achieved. I n contrast to previous attempts to ''trigger'' mechanisms whereby sele ct elements were weakened, all elements are given the same constitutiv e law in the present approach. A second method involves a re-gridding approach, together with the use of incremental displacements. In this approach, the displacement field is enhanced by interpolating between the nodal values.