随机谱下裂纹扩展统计模型

 结合断裂力学及概率随机过程理论,应用概率断裂力学方法研究随机谱下裂纹扩展的随机性。提出一种裂纹扩展统计模型预测裂纹随机扩展的统计分布特性。预测结果与大子样随机谱下裂纹扩展试验结果吻合良好。

A STATISTICAL MODEL OF FATIGUE CRACK GROWTH UNDER RANDOM LOADING

The analysis of fatigue crack growth damage accumulation is one of the most important tasks to the durability and damage tolerance design and the fatigue reliability design of structure. It is widely recognized that fatigue crack growth is fundamentally a random phenomenon, which can be predicted only in terms of probability. The phenomenon is much more complex if a structural element is subjected to random loading because of the fatigue crack growth retarding and accelerating effects. In thsi paper, by using the theorem of probabilistic fracture mechanics and stochastic process, a statistical model coupled with the root mean square method has been developed for the predicting of fatigue crack growth damage accumulation under random loading. Both the distribution of crack length at any given life and the distribution of load cycles to reach any given crack length are predicted. A special experiment, in which specimen size is 96 and specimen material is LY12CZ, an aluminium alloy, is conducted under a fighter random loading for the purpose of verification. A good correlation is obtained between the predicted distribution and the experimental results.