Fracture analysis of plates and shells using FEM and XFEM

摘要

Fracture mechanics is the field of mechanics concerned with the study of propagation of cracks in materials and recognizes the role of cracks in the performance of structures leading to damage tolerant design approach. Cracks or crack like defects is observed in many structures which may lead to their catastrophic failure under a tensile stress field. In this paper, the structural integrity of plates with surface and embedded cracks is investigated using ABAQUS FEA code and the fracture parameter-stress intensity factor (SIF)-is evaluated. Convergence study is conducted to arrive at the optimum mesh parameters using both the conventional finite element method and the extended finite element method (XFEM). The FE model is validated by comparing FE results with published numerical solutions. The effect of varying crack depth and location on SIF is studied. The FE results matched well with the closed-form solutions and experimental results. It is observed that the crack depth and its location have significant influence on SIF. The conventional finite element method requires a mesh that conforms to the crack geometry, typically with a very detailed, focused mesh at the crack tip. The crack front must be defined explicitly and must specify the virtual crack extension direction in addition to matching the mesh to the cracked geometry. XFEM gives better result for cylindrical shells without mesh refinement around crack tip.