基于PFM的B级钢侧架耐久性分析

Durability analysis of B grade steel side-frame based on the PFM method

基于概率断裂力学对B级钢货车侧架的圆角细节进行了模拟耐久性试验研究,提出了一种新的通用当量初始缺陷尺寸分布的计算方法,建立了裂纹超越概率模型,从存活概率P,应力水平σ,裂纹形成时间t和经济维修极限ae 4个角度评估了结构的损伤度,并结合实测的应力谱预测了其经济寿命。结果表明,裂纹萌生时间能很好地服从三参数Weibull分布,求得的通用EIFS分布参数通过了K—S检验,拟合效果很好。裂纹超越概率模型可以对结构产生的耐久性损伤进行定量度量,预测的经济寿命随裂纹穿越概率的增加呈现增长的趋势,验证了新的计算方法和概率模型的合理有效性。

Based on probabilistic fracture mechanics, the simulated durability test is performed to study the details with angle of side-frame of wagon bogie made of B grade steel. A new general computational method is pro- posed to evaluate the EIFS（equivalent initial flaw size） distribution, and the probabilistic crack exceedanee model is established. The structural damage value is evaluated from the viewpoints of the survival probability P, stress level tr, crack initiation time t and economic maintenance limit ae according to the actual measured stress spectrum. As a result, , and the corresponding economic life is predicted the TTCI （time to crack initiation） can be better characterized by the three-parameter Weibull distribution, and the validity of general EIFS distribution parameters obtained by the new computational method are verified by the K-S checkout. Furthermore, the structural damage value is quantitatively evaluated by the probabilistic crack exceedance model. The predicted economic life tends to increase with the increasing of the crack exceedance probability, and the rationality and validity of the new computational method and probabilistic model are proved.