Elastic-Plastic Simulation Study on 6005A Aluminum Alloy Crack Propagation Based on XFEM

Engineering components are susceptible to numerous fatigue fracture issues in the context of long-term service. The failure of a large number of components is often accompanied by the propagation process of fatigue cracks. The elastic-plastic finite element simulation analysis method was employed to deeply investigate the crack propagation mechanism of aluminum alloy materials under fatigue loading in this paper. First, a finite element model of the CT specimen was constructed based on the constitutive relationship of elastic-plastic materials. Additionally, the crack propagation rule was defined using the extended finite element method (XFEM). Subsequently, the validity and accuracy of the simulation model were verified through fatigue crack propagation experiments using a 6005A aluminum alloy CT specimen. Finally, the simulation model was further utilized to investigate the effects of different stress ratios and specimen thicknesses on the crack propagation behavior. The research findings demonstrated that the crack propagation simulation model established by the elastic-plastic material constitutive and the XFEM is capable of accurately simulating the crack propagation behavior of aluminum alloys under fatigue loading. In the validation CT model, the crack of the simulation model expanded from 13mm to 30mm after 160,000 cycles, and the expansion rate ranged from 2.5 x 10(-5 )to 3 x 10(-3). The height and width of the plastic zone at a crack length of 16 mm were 3.1mm and 2.0mm, respectively, which are very close to the experimental results. Furthermore, the simulation model also reveals the significant role of plastic flow at the crack tip in the fatigue crack propagation process.