Last modified: 2017-06-22
Abstract
Simulation of fatigue crack propagation and prediction of structural life is crucial to ensure the safety of engineering structure. The standard Extended Finite Element Method (XFEM) requires sufficiently fine mesh for crack propagation problems, which is computationally expensive and inconvenient to operate. In the present work, a simple dynamic adaptive mesh refinement method is proposed using the Virtual-node Polygonal Element method within the framework of the XFEM. Through this method, a multi-level refinement of the custom region near the crack tip can be realized. The refinement area changes dynamically with the crack tip position during the crack propagation process, so that the demands of the computational cost and accuracy can be reconciled. The domain based interaction integral approach is used to obtain the stress intensity factors(SIFs). The propagation direction of the crack is determined by the maximum circumferential stress criterion and the fatigue life of the cracked structure is evaluated by Paris Law. Then two simple examples are presented and the accuracy and convergence of the algorithm are verified. Compared with the standard XFEM, the proposed method requires far fewer degrees of freedom for the same accuracy. Finally, two fatigue crack growth problems are solved, and the SIFs and fatigue life cycle show good agreement with the results available in literature.