基于动态扭矩测试的综合传动系统主轴低周疲劳寿命预测与验证

为解决履带车辆综合传动系统主轴低周疲劳失效的问题，开展主轴疲劳样件检测及材料力学性能测试。通过实车测试获得主轴动态扭矩，在此基础上，建立主轴弹塑性有限元模型并预测主轴的低周疲劳寿命；进一步开展主轴低周疲劳台架试验，对寿命预测方法进行验证。研究结果表明：履带车辆在起步阶段下的冲击扭矩是造成综合传动系统主轴低周疲劳的主要载荷；由于双侧非对称的结构特点，导致主轴右侧冲击扭矩均值是左侧的1.54倍；主轴最大Mises应力为1 510 MPa， 最大应变为0.008 692 3，均发生在右侧输出花键与过渡圆弧交界位置的齿根处，与主轴疲劳断裂位置一致；实车条件下主轴能承受冲击扭矩的次数为17 082次；台架试验获得的主轴能承受冲击扭矩的次数为5 000，预测获得的主轴能承受冲击扭矩的次数为5 843次，仿真结果与试验结果基本吻合，验证了低周疲劳寿命预测方法的可行性。

Low-cycle Fatigue Life Prediction and Validation of Main Shaft of Power-shift Steering Transmission Based on Dynamic Torque Measurement

In order to solve the low-cycle fatigue failure of main shaft of power-shift steering transmission, the dynamic torque of main shaft was measured during pavement testing, and the fatigue sample was analyzed. An elastoplastic finite element model of main shaft is established to predict the low-cycle fatigue life of main shaft. The low-cycle fatigue test of main shaft was made to verify the low-cycle fatigue life prediction method. The results show that the impulsive torque of tracked vehicle in starting stage is the main cause of low-cycle fatigue of main shaft. For the asymmetric structure, the impulsive torque on the right side of main shaft is about 1.54 times of that on the left side. The maximum stress of main shaft is 1 510 MPa, and the maximum strain is 0.008 692 3, both occur at the root of boundary between output spline and transition arc on the right side, which is consistent with the fatigue fracture location of fatigue sample. The number of main shaft withstanding the starting impact torque is 17 082, the number of main shafts withstanding the starting impact torque obtained by bench tests is 5 000, and the number of main shafts withstanding the starting impact torque obtained by low-cycle fatigue life prediction is 5 843. The simulated results are basically consistent with test results, which verifies the feasibility of the low-cycle fatigue life prediction method. Key