恒幅及飞行模拟载荷下厚度对裂纹增长的影响

EFFECT OF THICKNESS ON FATIGUE CRACK GROWTH UNDER CONSTANT AMPLITUDE LOADING AND FLIGHT SIMULATION LOADING

不同厚度试样的疲劳裂纹扩展试验及断口微观分析表明,恒幅加载低应力比飞行模拟载荷条件下具有明显的厚度影响。考查了模型对厚度影响的预测能力。Newman的模型具有预测厚度影响的潜力,广义改进的wellenborg模型不含有厚度影响的考虑,即使通过调整约束系数α的方法也不能计及厚度的影响。厚度对裂纹增长影响的物理原因及模型化有待于进一步研究。

Fatigue crack growth tests were conducted in 7475—T7351 Al alloy with different thickness specimens. From constant amplitude loading test with lower stress ratio and flight simulation loading tests a significant thickness effect was observed. Crack growth life prediction was carried out using some famous models. It was found that Newman's model has the capability to predict thickness effect, generalized modified Willenborg model is not able to consider thickness effect even by adjusting constraint coefficient. The physical reason of thickness effect and the modeling consideration are two of the important subjects for successful crack analysis.