腐蚀疲劳裂纹扩展的马尔可夫链模型

在腐蚀环境下对LY12CZ铝合金试验件进行疲劳裂纹扩展试验,通过高倍显微镜观测并记录裂纹长度及相应的循环数。基于疲劳裂纹扩展数据的分散性及统计特性,提出用马尔可夫链模型模拟腐蚀疲劳裂纹的扩展,得到给定疲劳寿命时的裂纹超出数概率分布和给定裂纹长度时的疲劳寿命累积概率分布。将模拟结果与试验结果进行比较表明:马尔可夫链模型能够很好地模拟腐蚀疲劳裂纹扩展情况,为飞机结构的寿命预测和可靠性分析提供参考。

Markov Chain Model of Corrosion Fatigue Crack Growth

To study the problems of fatigue crack growth under corrosion conditions,an experimental work was carried out to obtain the crack growth data of a batch of LY12CZ aluminum alloy specimens.In view of the scatter and statistical nature of fatigue crack growth data,a rather universal stochastic Markov chain model is employed to analyze the data.The model gives us the crack exceedance probabilities of random crack size as well as the cumulative distributions of random loading cycle to reach a specified crack size.Through comparison between the analytical results and experimental data,it is found that the model can fit the experimental data rather well.It can be used for the prediction of fatigue life and reliability of aircraft structures made of the tested material.