基于SWT模型和威布尔分布的CFRP环带微动疲劳寿命预测

Fretting Fatigue Life Prediction of Pin-loaded CFRP Strap Based on SWT Model and Weibull Distribution

以铰销式碳纤维增强基复合材料(CFRP)环带为研究对象,基于SWT疲劳寿命预测模型,推导了服从威布尔分布的概率疲劳寿命预测方法。在给定的荷载条件下,建立ANSYS有限元模型,获得最不利破坏点处的应力、应变数值,并将其代入SWT模型计算微动疲劳损伤参量。根据微动疲劳寿命实验结果,采用最大似然估计法,建立在双参数威布尔分布下微动疲劳寿命与损伤参量的函数关系,得出在一定可靠度下的微动疲劳寿命预测值。结果表明:有限元的数值模拟结果与实验结果具有一致性,在四个荷载工况下,SWT模型损伤参量和威布尔分布参数值的三次项插值函数均方误差最小,得出95%可靠度下的疲劳寿命循环次数预测值均小于疲劳实验最小测量值,可作为工程设计值使用,同时说明了此疲劳寿命预测模型的正确性。

Based on the SWT fatigue life prediction model,the probabilistic fatigue life prediction method of pin-loaded CFRP strap obeying Weibull distribution is derived.The ANSYS finite element model is established to obtain the stress and strain at the most unfavorable failure location at given load conditions,and the SWT model is used to calculate the fretting fatigue damage parameters.According to the experimental results of fretting fatigue life,the maximum likelihood estimation method is used to establish the functional relationship between fretting fatigue life and da-mage parameters under two parameter Weibull distribution,and the prediction value of fretting fatigue life under certain reliability is obtained.It is shown that FEA results are consistent with that in the test.Under four load cases,the mean square error of the cubic interpolation function of the damage parameters and Weibull distribution parameters of the SWT model is the minimum.The fatigue life prediction model is validated by the comparision between the calculation results and the test,in which the predicted fatigue life under 95%reliability is less than the minimum mea-sured value in the test.It is obvious that the predicted model can be used in the design.