基于功率密度的大功率拖拉机变速箱壳体疲劳分析

Fatigue Analysis of Gearbox Shell of High Horsepower Tractor Based on Power Density

摘要:

引入功率密度的概念，提出功率密度与时频分析相融合的疲劳寿命预测方法，研究了应力幅值和载荷频率2个因素对大功率拖拉机关键零部件疲劳寿命的影响。以某型号88kW拖拉机为研究对象，在实际调研、用户反馈和有限元分析的基础上，确定变速箱壳体疲劳损伤危险点位置，搭建动态应力测试系统，采集拖拉机不同作业工况下的应力-时间历程。基于实测载荷，利用功率密度与时频分析相融合的疲劳寿命分析方法对拖拉机变速箱壳体的疲劳寿命进行预测，得到危险点的疲劳寿命为24001h，与基于Miner损伤理论和名义应力法分析得到的疲劳寿命（35676h）相比较，更接近实际工作寿命。本研究可为农机装备关键零部件的疲劳寿命预测提供更符合实际的分析方法

Abstract:

As an important power machine in agricultural machinery, high-powered tractors have a wide range of speeds and large horsepower, which can be loaded with different agricultural implements to achieve diversified operations. During the field operation, the gearbox housing is subjected to various loads, including the coupling of stress amplitude and load frequency, and it is necessary to perform a fatigue analysis of the gearbox housing close to the actual situation. The concept of power density was introduced, and the fatigue life prediction method combining power density and time-frequency analysis was proposed. The effects of stress amplitude and load frequency on the fatigue life analysis of key components of high horsepower were studied. Taking 88kW tractor as research object, a dynamic strain test system was set up, and the load-time history of 88kW tractor under different operating conditions was collected. Based on the measured load, the fatigue life analysis method of the 88kW tractor gearbox shell was predicted by the fatigue life analysis method combining power density and time-frequency analysis. The fatigue life of the dangerous point was 24001h, compared with the fatigue life (35676h) obtained from the nominal stress method based on Miner theory, the actual working life was more accepted. The research result provided a more realistic analysis method for the fatigue life of key components of agricultural machinery and equipment, and promoted the development of fatigue analysis theory.