Abstract: In order to find out the application method and life prediction pattern of the multi-axial high cycle fatigue criteria under random loads， based on a brand B-class car， the wheel center six component force signals of test field strengthening road were collected， and the dynamics model of the vehicle multi-body was established， and the virtual iteration method was used to obtain the load time of the knuckle and the connecting points of other parts. The finite element model of knuckle was established， and the accuracy of the finite element model was verified by modal simulation and modal test. The stress component time history was extracted for the node with the minimum lifetime value under von Mises stress. Three type critical plane calculation methods of eight high cycle fatigue criteria were studied， and the normal stress amplitude and shear stress amplitude of the critical surfaces were extracted by multi-axis cycle counting， and the equivalent stress amplitudes of different criteria were calculated， and the prediction rules of amplitude distribution and life expectancy were summarized. The results show that for the amplitude distribution and life prediction， the equivalent shear stress amplitude of the Zhang-Yao criterion is large， and the prediction life is as 1.09×105 times， which is more conservative than that of other criteria. The large stress amplitude of McDiarmid criterion only accounts for 3.4%， the predicted life is as 1.25×106 times， significantly higher than that of other criteria， and the prediction life value of improved McDiarmid criterion is significantly reduced. For the calculation cost， the von Mises criterion does not need to extract the critical surface and the multi-axis cycle count， so the applications are the most convenient. Findley criterion extraction critical surface processes require the calculation of normal and shear stress data for all planes， so the calculation cost is highest.

Key words: random load, multi-axis cycle count, critical plane, high cycle fatigue criterion, equivalent stress amplitude

摘要： 为探明汽车底盘构件在随机载荷下多轴高周疲劳准则的应用方法与寿命预测规律，以某品牌B级轿车为研究对象，通过采集试验场强化路轮心六分力信号，建立了整车多体动力学模型，应用虚拟迭代法获取转向节与其他零件连接点的载荷时间历程；建立转向节有限元模型，通过模态仿真与试验验证了有限元模型的准确性；提取了von Mises应力下寿命值最小节点的应力分量时间历程；研究了8种高周疲劳准则所基于的3种类型临界平面的计算方法，通过多轴循环计数提取临界面上正应力幅与剪应力幅，并计算不同准则对应的等效应力幅，总结幅值分布与寿命预测规律。研究结果表明，在幅值分布与寿命预测方面，Zhang-Yao准则的等效剪应力幅值整体偏大，预测寿命为1.09×105周次，较其他准则偏于保守；McDiarmid准则的大应力幅仅占3.4%，预测寿命为1.25×106周次，明显大于其他准则的预测寿命值，而改进的McDiarmid准则预测寿命值明显减小。在计算成本方面，von Mises准则无需提取临界面与多轴循环计数，应用最为便捷；Findley准则提取临界面过程需要计算所有平面的正应力与剪应力数据，故计算成本最高。

关键词: 随机载荷, 多轴循环计数, 临界平面, 高周疲劳准则, 等效应力幅