防振橡胶材料疲劳寿命可靠性分布模型研究

STUDY ON RELIABILITY DISTRIBUTION MODELS OF FATIGUE LIFE OF ANTI-VIBRATION RUBBER MATERIALS

橡胶隔振器主体隔振橡胶疲劳寿命具有很大的分散性,仅采用裂纹萌生法和裂纹扩展法等确定方法是不足的,还需从概率的角度对橡胶结构的疲劳寿命做出合理的预测。基于橡胶单轴拉伸疲劳试验测试数据,推导三参数威布尔分布(Three Parameters Weibull Distribution,3PWD)和对数正态分布(Logarithmic Normal Distribution,LND)两种典型概率分布模型对应的疲劳剩余寿命的累积分布函数和概率密度函数,应用到剩余寿命可靠性的预测中,以此确定不同概率分布模型下所需最小的试样数和工况数。结果表明,3PWD更适合用来表征橡胶疲劳寿命的概率分布规律;橡胶疲劳试验样本数和工况数的最小值分布在4~6个之间;在确定中值寿命时应优先选择对数平均值作为后续的疲劳分析。研究工作可以为橡胶隔振器抗疲劳设计和试验提供指导。

Fatigue life of filled natural rubbers used in isolators is very dispersive owing to many uncertainties such as loads and temperature.Conventional crack initiation methods and crack propagation methods to determine fatigue life of rubbers are insufficiently to characterize the phenomenon;thus,probabilistic methods are desired in practical engineering.Based on the test data of uniaxial tensile fatigue experiment of rubbers,the cumulative distribution function and probability density function of residual fatigue life corresponding to two typical probability distribution models of three parameters Weibull distribution(3 PWD)and logarithmic normal distribution(LND)were derived and applied to the prediction of residual life reliability,in order to determine the minimum required under different probability distribution model of sample number and working condition number.The results showed that 3 PWD was more suitable to characterize the probability distribution of rubber fatigue life.The minimum values of the number of rubber fatigue test samples and the number of working conditions are distributed between 4 and 6.The log mean should be preferred for subsequent fatigue analysis when determining the median life.The research can provide guidance for the anti-fatigue design and test of rubber vibration isolators.