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目的：分析转向架用SMA490 BW钢对接接头的应力集中系数,提高转向架焊接接头的超高周疲劳性能,保障高速列车的安全可靠运行。方法对转向架用SMA490 BW钢对接接头的超高周疲劳试样进行有限元建模,应用有限元软件ABAQUS计算不同焊趾过渡圆弧半径、焊趾倾角下接头的应力集中系数,并通过Origin软件分析建立应力集中系数(Kt)与焊趾过渡圆弧半径(r)、焊趾倾角(θ)的关系。结果当r=0.2 mm,θ分别为10°,20°,30°,40°,50°,60°时, Kt 分别为1.391,1.747,1.976,2.263,2.425,2.525；当θ=30°,r 分别为0.2,0.5,1,1.5,2,2.5,3,4 mm 时,Kt 分别为1.976,1.763,1.535,1.419,1.345,1.306,1.257,1.201。结论应力集中在对接接头焊趾处较大, r和θ对K t 有显著影响。 r相同时,Kt 随θ的增大而增大；θ相同时,Kt 随r的增大而减小。应力集中系数关系方程对于焊趾处应力集中的改善以及转向架对接接头的超声疲劳试样设计具有指导意义。

Objective To analyze the stress concentration coefficient of SMA490BW steel butt joint for bogie, which has an im-portant significance for improving VHCF properties of bogie welded structure and ensuring the safe, reliable operation of high-speed train. Methods Finite element model of very high cycle fatigue sample of SMA490BW steel butt joint for bogie was built. The in-fluences of joint geometric parameters ( weld edge transition arc radius r,weld toe inclination angleθ) on stress concentration coeffi-cient Kt of weld toe were studied based on the finite element software ABAQUS, and the relationship between the stress concentra-tion coefficient and the geometric parameters was analyzed and established based on regression analysis of Origin software. Results When the weld edge transition arc radius r was 0. 2 mm, the stress concentration coefficient Kt was 1. 391, 1. 747, 1. 976, 2. 263, 2. 425, 2. 525 respectively at weld toe inclination angle θ of 10°, 20°, 30°, 40°, 50°, 60°;when the weld toe inclination angleθwas 30°, the stress concentration coefficient Kt was 1. 976, 1. 763, 1. 535, 1. 419, 1. 345, 1. 306, 1. 257, 1. 201 respectively at weld edge transition arc radius r of 0. 2, 0. 5, 1, 1. 5, 2, 2. 5, 3, 4 mm. Conclusion Stress concentration at weld toe of butt welded joint was relatively large, and weld edge transition arc radius r and weld toe inclination angle θ played important roles in stress concentration coefficient Kt . For the same weld edge transition arc radius r, the stress concentration coefficient Kt at weld toe increased with increasing inclination angle θ. While in the case of the same weld toe inclination angle θ, the stress concentration coefficient Kt at weld toe decreased with increasing transition arc radius r. The stress concentration coefficient equation has a gui-ding significance to the improvement of stress concentration at weld toe and the design of ultrasonic fatigue sample of butt joint for bogie.