基于系统PSN曲线的齿轮箱疲劳可靠度评估

蒙特卡罗方法可以准确评估复杂机械系统疲劳共因失效概率,但效率偏低,因此提出系统PSN曲线的概念和基于此概念的系统可靠度蒙特卡罗评估方法。在给定的恒幅载荷下,基于同一零件的疲劳寿命在不同应力水平下的概率分位点具有一致性的原则,对系统中零件PSN曲线进行随机抽取;根据线性累积损伤法则和相应的系统可靠度模型,得到齿轮传动的恒幅载荷下的疲劳寿命分布,拟合恒幅载荷与寿命分布之间的关系得到系统PSN曲线。将系统视为一个零件,完成"零件"-"系统"-"零件"的寿命分析过程。通过损伤等效原则,将随机载荷下的复杂串联系统可靠度评估问题转化为恒幅载荷下零件的可靠度评估问题。

Assessment of gearbox fatigue reliability based on system PSN curve

To improve the efficiency of Monte Carlo simulation applied to evaluating the common cause failure probability of complex mechanical system,the concept of system fatigue life PSN curve was set up first, and then a Monte Carlo method for system reliability assessment based on this concept was proposed. With a given constant load,based on the correspondence of probability percentiles between specimen fatigue lives as-sociated with different cyclic stress levels,every single PSN curve of component can be extracted stochastical-ly.According to the linear cumulative damage rule and the corresponding system reliability model,the fatigue life distribution of gear-series-system was acquired.System PSN curve can be obtained by fitting constant load and life distribution.The system can be treated as a component,and the life analysis process of component-system-component has been completed.By means of damage equivalence principle between random load and constant load,the problem of reliability assessment of a complicated series system under random load can be converted to the problem of reliability assessment of component under constant load.