| The series of cold-rolled 301L stainless steel plates are main material in mannufacture of light-weight vehicle body,with a large number of EMU's with the 200 km/h put into use and the expansion of metro, suburban railway,light-weight vehicle demand is rapidly increasing. At present, the domestic cold-rolled stainless steel sheet has been put into use, but it is lack of basic research in the application field,there are many problems demanding prompt solution in stainless steel vehicle body design, manufacturing process. In this paper, the research object is domestic 301L-HT plate, based on the fatigue properties of single spot welding in the early stage,to static tensile shear strength test,high-cycle fatigue tests and finite element failure simulation of multi-spot welding specimens,study on the relationship between static strength, fatigue strength and the number and arrangement of spot, optimizing the structure and welding process parameters of multi-spot welding, the body design, manufacture provide basic reference data and theoretical basis, provide basic reference data and theoretical basis for the vehicle body design and manufacture.The results show that a good linear relationship between static strength and the number of spot,arrangement of spot no effect on the static strength; With the increase of number of spot,The stiffness and fracture absorbed energy of spot welding specimens will be increase,the stiffness of equilateral triangle arrangement of spot better than other;along the tensile direction and vertical arranged get the maximum fracture absorbed energy;Fatigue specimens cracked at two-sided through-thickness sheet, fatigue crack appeared initially in HAZ of inner surface of lap plates,along the thickness direction extended to outer surface; a linear relationship between fatigue limit of 99.9% survival rate and the number of spot,while the fatigue limit of 50% survival rate only for single,double, four spot welding specimens, three spot samples get the lower fatigue limit and almost double spot,because of unbalanced distribution of load.ANSYS/LS-DYNA finite element analysis software is used to simulate the failure analysis of tensile shear test of multi-spot welding specimens. The results show that exist serious stress concentration in part of spot of multi-spot welding specimens, resulting in the lowest strength of spot welded joints and the fatigue crack initiation and growth of the position;The results of finite element analysis,fatigue testing and fracture analysis show that the arrangement of single spot,double-spot, four-spot structure is more reasonable and conducive to balance distribution of load,the performance of resistance fatigue is better than triple-spot specimens. Finite element analysis software is feasible to simulate the failure analysis of tensile shear test,even partial replacement of shear tensile test.
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