多处损伤LY12CZ铝合金加筋板的疲劳裂纹扩展研究

进行了多处损伤LY12CZ铝合金加筋板的疲劳裂纹扩展的分析与试验研究。给出了典型的随机载荷谱下铝合金加筋板多裂纹扩展的预计方法。用组合法和类比法计算多处损伤LY12CZ铝合金加筋板的应力强度因子。考虑每个载荷循环裂纹之间的相互作用影响,以Walker裂纹扩展公式和Willenborg-Chang裂纹扩展公式为基础,用循环续循环进行裂纹累积,用虚拟施加剩余强度载荷和裂尖韧带塑性区连通判据确定临界裂纹尺寸。进行了恒幅谱载荷及程序块谱载荷下加筋板多裂纹的扩展试验研究。对比了铝合金多裂纹扩展的分析预计结果和试验结果,对比结果表明,预测的寿命与试验结果吻合较好。

Study on Fatigue Crack Growth of Stiffened LY12CZ Aluminum Alloy Panels with Multiple Site Damage

An analytical and experimental study were performed on the fatigue crack growth of stiffened LY12CZ Aluminum Alloy panels with multiple site damage(MSD).A typical method was presented for the prediction of multiple crack growth in stiffened panel under random fatigue load spectrum.The stress intensity factor was calculated by the combined approach and analytical method.The interaction between cracks was considered at each load cycle.The Walker equation and the Willenborg-Chang equation for crack were used as the basis for the calculation of cycle-by-cycle crack size accumulation;the fictitious residual strength load is applied,and the residual strength criterion of crack tip ligament plastic zone linkup is used for the determination of critical crack size.Experimental studies for crack growth of stiffened panels with multiple cracks were performed under both constant-amplitude load and program block spectrum load.The experimental results for multiple crack growth were compared with analytical predictions.It is shown that the analytical predictions of the crack growth life coincide well with the experimental ones.