Crack insertion, meshing and fracture analysis of structures using tetrahedral finite elements

In this study, a method and corresponding tools are presented to insert a three-dimensional crack of a given size and location into a finite element model without any cracks using fully unstructured finite elements. For research purposes, publicly available two and three-dimensional meshing software, Triangle© and Tetgen©, are utilized and integrated with an in-house developed program to compatibly select and re-mesh the three-dimensional crack region of the original input model. Within the procedure, the boundary conditions and loads existing on the original model are also book kept and transferred to the new model containing the crack. Next, the new finite element model, which now contains the crack geometry, the loads and boundary conditions, is solved in a general-purpose finite element program employing enriched elements. The above procedure is demonstrated on a series of surface crack problems in finite-thickness plates including mixed-mode fracture conditions. The obtained results are compared to well-known solutions available in the literature. These comparisons showed good agreement for all cases analyzed. It is, therefore, concluded that the procedure developed is valid, efficient and yields accurate three-dimensional fracture solutions.