重型拖拉机液压机械无级变速器箱体疲劳寿命分析

针对重型拖拉机液压机械无级变速器（简称HMCVT）实际作业过程中由于箱体受载复杂，载荷不对称从而易发生疲劳破坏的问题。本文提出了一种基于虚拟样机技术修正材料S-N曲线对HMVCT箱体进行疲劳寿命预测的方法。利用Adams建立变速器刚柔耦合虚拟样机模型，提取HMCVT箱体各轴承孔处的动态激励。综合考虑HMCVT箱体载荷特点，结构参数，表面工艺等因素，重新拟合了箱体结构S - N曲线，根据Miner线性累计损伤理论对HMCVT箱体进行疲劳寿命预测。结果表明，结构S - N曲线较传统材料S - N曲线有较大程度的修正，HMCVT箱体危险点疲劳累计损伤量为D = 4.8353×10?8，变速箱寿命为57447 h，满足全寿命使用要求。该研究为设计及优化农机装备关键零部件时的疲劳寿命预测提供了参考。

Fatigue Life Analysis of Hydro-mechanical Continuously Variable Transmission Box of Heavy Tractor

In order to solve the fatigue failure problem of the hydro-mechanical continuously variable transmission(HMCVT) boxof the heavy tractor due to the complex load in the actual process, a fatigue life prediction method for HMCVT box based on the virtual prototype technology was proposed. A rigid-flexible coupling virtual prototype model for HMCVT box was established based on Adams. Besides, the dynamic excitation of each bearing hole of gearbox shell under different working conditions was acquired. S - N curves of HMCVT boxwere re-fitted under the consideration of load characteristics, structure parameters, and surface technology. Finally, the prediction offatigue life of the HMCVT boxwas conducted based on the Miner linear accumulative damage theory. The results indicated that the S - N curve of the structure has a certaindegreeof modification comparing with the traditional material. The dangerous point of the shell was located at the bore of the idler axle under the dynamic excitation, while the fatigue cumulative damage (D) was 4.8353×10?8, and the life of the HMCVT box is 57447 hours. So, the structure design of the box was conservative and satisfied the requirement of service time.