飞机铆钉孔排布及孔边裂纹对2024-T3铝合金剩余强度的影响

Effect of arrangement of rivet holes and cracks in fuselage on residual tensile strength of 2024-T3 aluminum alloy

基于数字图像相关技术,研究了老龄飞机机身外蒙皮含铆钉孔和裂纹的2024-T3铝合金板材剩余强度性能。首先,通过拉伸实验研究了铆钉孔行距和列距对剩余强度的影响;其次,预制了4类裂纹,模拟飞机蒙皮多部位损伤现象,分析了其方向变化对含交错孔试样剩余强度影响,并进一步对裂纹扩展路径进行了讨论;最后,对净截面屈服准则进行了修正。结果表明:剩余强度随着铆钉孔列距的增加而增大。当列距一定时,试样剩余强度随行距的增大而升高,当行距大于32 mm时,剩余强度出现下降趋势。修正后的净截面屈服准则可以较好地预测含多部位损伤交错孔结构的剩余强度值,预测误差在8%以内。

The residual tensile strength(RTS)of 2024-T3 aluminum alloy sheet with rivet holes and cracks in fuselage of aged aircraft was evaluated by using digital image correlation(DIC)technology.Firstly,the effects of row spacing and column spacing on RTS were studied by tensile test.Then,four types of cracks were prefabricated to simulate the multi-site damage phenomenon of aircraft skin,the influence of the change of crack direction on the RTS of samples with staggered holes was analyzed,and the crack growth path was further discussed.Finally,the net section yield criterion was modified.The results show that the RTS increases with the increase of the column spacing.When the column spacing is fixed,the RTS increases with the increase of the row spacing,and when the row spacing is greater than 32 mm,the RTS tends to decrease.The modified net section yield criterion can predict the RTS of the staggered hole structure with multi-site damage,and the prediction error is less than 8%.