Equivalent meso-scale constitutive damage model for an aluminum alloy welded by oscillating laser welding

Analysis of mechanical properties of welded joints considering material and geometric inhomogeneity helps to improve the accuracy of joint performance prediction. The influence of material and geometric inhomogeneity on the mechanical properties of welded joints, encompassing stress–strain behavior, microstructural characteristics, and hardness profiles, was investigated. The present study focuses on the aluminum alloy oscillating laser welded (OLW) joint and employs response surface method and entropy weight method to establish an approximate model, thereby determining the optimal welding parameters. Subsequently, the stress–strain characteristics and microstructure of the weld (WM), base metal (BM), and heat-affected zone (HAZ) were obtained. To characterize the overall stress–strain characteristics of welded joints, three equivalent meso-damage model methods based on the Gurson-Tvergaard-Needleman (GTN) model were proposed, and the advantages and disadvantages of the methods were comprehensively evaluated by comparing the accuracy and efficiency of joint performance prediction. In addition, the stress–strain simulation analysis of the joint’s sub-region was performed to verify the effectiveness of the three-material equivalent model method in predicting the performance of the welded joint sub-region. Built on the study contents discussed above, the equivalent meso-damage model suggested in this paper completely accounts for the joint’s inhomogeneity and can accomplish high-precision prediction of the joint’s overall and local performance.