基于断裂力学的齿轮箱螺栓的失效分析及改进研究

指出由于铝合金齿轮箱和钢制螺栓的热膨胀系数不同．在齿轮箱温度升高后产生附加的温差载荷．此温差载荷是螺栓失效的根本原因，由此依据相关公式提出了改进措施。在对联接螺栓进行受力分析的基圳上应用断裂力学理论．对改进前后螺栓的疲劳寿命进行了预测。原结构的疲劳寿命短．不满足要求．改进后的结构满足要求：改进措施是有效的，这也为齿轮箱的设计提供了参考。并对45钢和40Cr这2种材质的螺栓进行了对比．进一步说明失郊的根本原因不是材质的问题．而是温差载荷

Failure Analysis on Gear Case Bolt Based on Fracture Mechanics and Improvement Research

It is pointed out that due to the difference of the temperature expand coefficient of aluminum alloy gear case and steel bolt, when the temperature of the gear case increased,additional temperature-difference load is generated,which is the ultimate reason of the bolt failure.Improvement measures are proposed according to relative formulas.On the basis of the analysis on the forces applied to the connecting bolts,the fracture mechanics theory is applied and the fatigue lives are forecasted for the bolts before and after the improvement.The fatigue life of the bolts with original structure is short and do not meet the requirement,while the bolts after improvement meet the requirement.The improvement measures are efficient,which could be taken as reference for the design of gear case.The bolts of 45 steel and 40Cr are compared, which further clarifies that the failure reason does not lie in the material,but in the temperature difference load.