A B.E. approach for elasto-damaging fracture mechanics

A great interest has been devoted in the last years to the description of the non-linear phenomena accompanied by highly localised strains occurring in the brittle materials. Such interest has triggered off the development of various techniques in the Finite Element (FE) context. A comparative study on such techniques is given in [1]. A different approach which results to be more suitable in the Boundary Element (BE) context is the fictitious crack model: the developing fracture zone is modeled in a softening way, i.e. contact stresses decrease while the crack opening displacement increases. The dual boundary element method (DBEM) developed by [4] has shown to be very effective when applied to the fictitious crack model. The above approaches do not cope properly with the existence of a narrow fracture process zone containing a large number of distributed microcracks. The continuum damage mechanics is an attempt to link the distributed microcracking with the fracture mechanics. Its main drawback is the ill-posedness related to the strain softening behavior produced by the material damage, i.e. the numerical solution is non-objective with respect to the choice of the mesh. Following some recent results (see [2]- [3]), the Authors couple a simple nonlocal damage model (which overcomes the mesh-dependence) with the crack analysis in order to describe the formation and propagation of a crack in brittle materials