基于连续损伤力学的剩余疲劳寿命随机预测

Stochastic prediction of the remaining fatigue life based on continuum damage mechanics

由于材料特性和外部加载具有随机性,变幅加载下的剩余疲劳寿命往往具有很大的分散性。因此,为了量化由材料特性和外部加载引起剩余疲劳寿命的不确定性,提出一种两级加载下剩余疲劳寿命预测方法,该方法主要包括4个步骤:首先,考虑外部加载的随机性,应用基于连续损伤力学的非线性损伤累积模型;其次,考虑材料特性的随机性,采用不同可靠度下三参数应力寿命(S-N)曲线;然后,为了筛选对剩余疲劳寿命的随机性有显著影响的模型参数,引入基于Sobol方法的全局敏感性分析;最后,利用K-L散度量化预测和实验剩余疲劳寿命概率分布之间的差异。此外,借助热轧16Mn合金钢的疲劳试验数据验证所提方法的有效性。

Due to the randomness of material properties and external loading,the predicted remaining fatigue life under variable amplitude loading often has a very great dispersion.Thereby,to quantify the uncertainty of the remaining fatigue life arising from material properties and external loading,this paper proposes a remaining fatigue life prediction method under two-level loading.This proposed method mainly consists of four steps.Firstly,considering the randomness of external loading,a nonlinear damage accumulation model based on continuum damage mechanics is applied.Secondly,considering the randomness of material properties,three-parameter S-N curve under different reliability is adopted.Thirdly,in order to screen the model parameters that contribute greatly to the randomness of the predicted remaining fatigue life,a global sensitivity analysis based on Sobol method is introduced.Finally,the K-L divergence method is utilized to quantify the differences between the predicted and the probability distribution of the experimental remaining fatigue life.In addition,the effectiveness of the proposed method is verified through the fatigue test data of hot-rolled 16 Mn alloy steel.