国产轿车后轴强化路耐久性断裂试验研究

Durability fracture tests for rear axle of a self-made car on enhanced roads

为研究国产某型轿车试验场强化路可靠性试验阶段出现的后轴断裂问题,采集断裂部位附近的应变载荷谱,应用Neuber法则和循环应力-应变滞回环曲线方程,将名义应变历程转换为断裂位置的局部应力-应变响应,根据Manson-Coffin模型修正平均应力对疲劳损伤的影响,在INFIELD软件中编程计算断裂裂纹处的损伤。利用电磁激振器对后轴与车身进行振动模态扫频,识别后轴振动频率与强化路激励频率及车身振动频率关系。试验结果表明,裂纹处的疲劳损伤主要集中在搓板路面,搓板路强迫振动激励频率为24.07 Hz时,后轴振动模态频率与搓板路激励频率较接近而引发共振,致使后轴因高应力集中产生较大应变和疲劳损伤发生振动疲劳断裂。

In order to study rear axle fracture problems of a self-made car appearing in reliability test stage on enhanced roads of an automotive proving ground, the strain loading spectrum near the rear axle fracture location was collected, Neuber rule and the cyclic stress-strain hysteresis loop curve equation were used to convert the nominal strain history into the local stress-strain response of the fracture location, the impact of mean stress on fatigue damage was corrected according to Manson-Coffin model, and INFIELD software was used to calculate the fatigue damage of the rear axle fracture. The electromagnetic vibrators were used to sweep the vibration modal frequencies of the rear axle and the body, to identify the relationship among the vibration frequencies of the rear axle, the excitation frequencies of enhanced roads and the vibration frequencies of the body. The test results showed that the rear axle fatigue damage mainly concentrates on the washboard road, and when the forced vibration excitation frequency of the washboard road is 24.07 Hz, the vibration modal frequency of the rear axle is close to the excitation frequency of the washboard road, leading to resonance and making the rear axle subjected to large strain and fatigue damage and then the vibration fatigue fracture appears due to high stress concentration.