Crack growth based FEM with embedded discontinuities

University essay from KTH/HÄllfasthetslÀra

Abstract: In recent years there have been a major developments in the computational mechanics community when it comes to modelling of fracture mechanics. There are now several well established numerical methods that are implemented in commercial programs such as: Phase Field Modelling, Enhanced Assumed Strain (EAS), Smeared Crack Methods, Extended Finite Element Method (XFEM) and Partition of Unity Finite Element Method (PUFEM). This work has been based on PUFEM and it has been of interest to investigate if this numerical method can be combined with plastic deformation. The reason for this is that it has been known that complex structural and material phenomenon such as embrittlement of steels or composites show a variation of fracture toughness. Thus more advanced approaches are required to capture the response of such structures and materials. The analysis was split in to three parts. First, a benchmark analysis was done with linear tetrahedral elements and, which has been implemented in previous applications. Thereafter the same analysis was done for quadratic tetrahedral elements. Finally, the interface between plasticity and PUFEM was implemented and was analysed with the same geometries as in the benchmark case. The analysis show that it is possible to combine plasticity in PUFEM setting and that it has a possibility to be used in future applications.

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