Adaptive strategies for explicit 3D crack propagation simulations in brittle materials by means of a mixed continuous-discontinuous model

Complete three-dimensional crack propagation with minimal incorporation of restrictions to the crack path is still a challenge. For efficient modeling of regions with highly localized strains, enriching the standard GALERKIN finite element approximation has become an established method. In this context the Strong Discontinuity Approach (SDA) is used to enrich the standard regular part of the finite element interpolation with Enhanced Assumed Strains (EAS). This ensures that the resulting discontinuities in the displacement field can be traced in a realistic way allowing a non-geometrical representation of crack discontinuities. Within the crack propagation context, a threshold value for the development of a crack has to be obtained. By means of a mixed continuous-discontinuous model, the element representation is subsequently transfered from a non-geometrical to a geometrical one. Therefore, full adaptive procedures have to be incorporated into a three-dimensional finite element model. To ensure that element sizes remain as big as possible, different adaptive element splitting procedures are necessary.