The Layout And Fatigue Life Analysis Of Laser Welds For Side Wall Of Stainless Steel Car Body

The current stainless steel body panels and reinforced plate laser welding structure is mainly used continuous welding.But the long distance of the continuous welding process is difficult,it's easy to have a lack of penetration and weld gap,resulting in the mechanical properties of welded structure decreased.To solve this problem,the laser segmented welding be used in side wall,and the welding defects are reduced by discontinuous welding.In this paper,based on the tensile test and fatigue test results of laser welding structure of A and B model,the arrangement and fatigue performance of laser welds are analyzed.The influence of weld length and weld spacing on the performance of laser segment welding structure was simulated by ABAQUS finite element software,and the arrangement of laser welds was optimized based on fatigue performance.The tensile analysis results show that the tensile properties of the laser segment welding structure have decreased compared with the continuous laser welding structure.When the plate width is constant,the shorter the weld length,the worse the tensile properties of the welded structure.Based on the maximum equivalent plastic strain criterion to predict the minimum length of a single weld shall not be less than 13.3mm,The ratio between the weld length and the weld spacing shall not be less than 2:1 to ensure that the static strength of the laser segment welding structure satisfies the design Claim.In addition,increasing the weld width and depth of penetration can significantly improve the tensile properties of welded structuresThe results of the optimization analysis show that when the gap is constant,the longer the weld length is,the stronger the fatigue performance is.The fatigue performance is the best when the weld length and the pitch ratio are 3:1,but continue to increase the length of weld fatigue performance drops.When the length of the weld is constant,the smaller the weld spacing,the stronger the fatigue performance.Also,the weld gap is more noticeable for fatigue performance.When the total length of the weld and the weld spacing of the laser welded structure are the same,the weld structure exhibits excellent fatigue performance:multi-stage welds and short solder spacing.The results of fatigue analysis show that the high-cycle fatigue fracture of the non-fused-lap welding structure is near the weld at the outer plate,and the low-cycle fatigue fracture is near the weld at the inner plate.The stress concentration at the weld is the main reason for its fracture.The fatigue life of laser welding structure is predicted by local strain method.The results show that the low-cycle fatigue life of the laser welding structure is relatively accurate based on the local strain method,but the method predicts high cycle fatigue life are too large.