实况下机械零件的动态可靠性分析

考虑不同工况下载荷变化和强度退化对机械零件可靠性的影响，采用雨流计数法对工况载荷进行统计处理，运用Goodman直线修正法与线性积累损伤法则估计出零件的疲劳寿命.在此基础上，利用等时间段内最大载荷替代载荷变化，Gamma过程模拟强度随机退化的方法来建立渐变可靠性数学模型，最后由随机摄动理论和四阶矩法相结合推导出可靠性灵敏度的表达式.以采煤机扭矩轴为例，估算出扭矩轴在实际载荷下的疲劳寿命，给出各参数变量在疲劳寿命内动态可靠性灵敏度变化规律，分析了参数变量改变对扭矩轴可靠性的影响，并用Monte Carlo仿真进行了验证，结果表明所采用的动态可靠性分析过程符合实际工况，能够为实况下机械零件的动态可靠性分析提供一种方法.

Dynamic Reliability Analysis of Mechanical Parts Under Actual Operation Conditions

The fatigue life of the parts were estimated by using the Goodman linear correction method and the linear cumulative damage rule， and the working load was statistically analyzed by the rain flow count method， considering the impact of the load change and the strength degradation on the reliability of mechanical parts. Then， the gradient reliability mathematical model was set up with maximum load in equal time to replace the variable load by using Gamma random process simulating strength degradation. Finally， the expression of reliability sensitivity was derived by stochastic perturbation theory and four rank moment method. The torque shaft of coal mining machine was taken as an example， the fatigue life of the shaft under actual load was estimated and the each parameter variables′ variation rule of dynamic reliability sensitivity during the fatigue life was given. Furthermore， the influence of the parameter variables′ variation on torque shaft reliability was analyzed， and the Monte Carlo simulation method was used to verify the results. All analysis results show that the dynamic reliability analysis process adopted conforms actual working conditions， and can provide a method for dynamic reliability analysis of mechanical parts in real situations.