Simulation of Interactions between Pores and Cracks inside Fusion Welded Aluminum Alloys

In order to investigate the influence of interactions between cracks and pores within fusion welded aluminum alloys on the performance of the joints, polygonal elements each embedded with a single elliptical hole or multi cracks were constructed based on the hybrid polygonal element (HPE). Then, a plane stress model was formulated for a fusion welded aluminum alloy joint, which consisted of both a main crack and arbitrarily distributed pores, and the influences of the distribution of these pores on the cracks initiated from the weld root were studied. The result shows that errors between the HPE method solutions and the theoretical ones can be limited to the level of 0.5%, even if sparse meshes are used. Smaller-sized pores in the bottom of the welding joint can increase the stress intensity factor (SIF)Ⅰand SIFⅡby 2.15% and 324%, respectively, showing a significant enhancement effect on the stress field of the crack tip; what's more, the smaller the distance between pores and cracks, the greater the coupling effect.