基于田间实测载荷的拖拉机转向驱动桥壳疲劳寿命分析

针对拖拉机作业过程中承载幅值大、随机非对称的特点,综合考虑应力集中、尺寸效应、表面质量和载荷特性等因素对疲劳寿命的影响,从相对应力梯度、疲劳损伤区域和实测载荷应力比3方面对传统应力场强法进行优化,获取修正S-N曲线,结合拖拉机田间作业的实测载荷数据,分析某88 kW拖拉机转向驱动桥壳的疲劳寿命,并与传统应力场强法的预测结果进行对比。结果表明,相比于传统方法的预测结果(31 860 h),优化后的应力场强法的预测结果(25 467 h)更接近实际工作寿命(24 000 h)。本研究可为农机装备关键零部件的疲劳寿命预测提供分析方法。

Fatigue Life Analysis of Tractor Steering Drive Axle Housing Based on Field Measured Loads

When a tractor is working in the field,its key components are usually subjected to harsh geographical environment and weather conditions,moreover,the complex and variable loads,these make the key components of the tractor prone to fatigue failure.In order to accurately predict the fatigue life of large-horsepower tractors and provide theoretical basis for the design of key components of tractors,the stress field intensity method was adopted to analyze the fatigue life of steering drive axle housing of an 88 kW tractor.The fatigue-life influencing factors,including stress concentration,size effect,surface quality and load characteristics were considered to optimize the traditional stress field intensity method.Traditional stress field intensity method was optimized from three aspects,i.e.the relative stress gradient,the fatigue damage area,and the measured load stress ratio,in order to obtain the modified S N curve.The modified S N curve was combined with the field measured load data to perform the fatigue life analysis of the steering drive axle housing,followed by comparing the prediction results of the optimizing stress field intensity method with the traditional method.The fatigue life of the dangerous point predicted by the optimizing method was 25467 h,while the fatigue life obtained from the traditional method was 31860 h.The comparison results showed that the optimized stress field intensity method was more accurate,since the perdition result was closer to the actual working life(24000 h).The research result provided a more practical method for predicting the fatigue life of the key components of agricultural machinery equipment.