对7050-T7451铝合金直耳片、对称斜耳片和非对称斜耳片进行了不同方向、不同大小载荷下的疲劳裂纹扩展试验, 对比分析了疲劳裂纹扩展曲线和裂纹扩展路径。结果表明: 在加载方向和载荷峰值相同时, 对称斜耳片的疲劳寿命高于直耳片的, 且增大斜切角有利于提高其疲劳寿命; 对称斜耳片受纵向疲劳载荷时的疲劳寿命高于受斜向疲劳载荷时的, 初始裂纹在斜切角较小侧的非对称斜耳片更容易发生疲劳断裂; 随着加载角度的增大, 耳片的裂纹扩展方向与载荷方向的夹角逐渐减小; 受横向斜载荷的斜耳片, 其耳孔内侧首先出现裂纹, 其扩展方向与载荷方向的夹角约为45°。

The fatigue crack growth experiments under different loads in different directions were conducted on the straight lug, symmetrical and unsymmetrical tapered lug of 7050-T7451 aluminum alloy, and then the fatigue crack growth curves and crack growth paths were analyzed and compared. The results show that under the same loading direction and peak load, the fatigue lives of the symmetrical tapered lugs were higher than those of the straight lugs and the increase of the oblique angle was in favor to improve the fatigue life. The fatigue life of the symmetrical tapered lug subjected to the vertical load was higher than that under the oblique load. The unsymmetrical tapered lugs with initial cracks at the side of relatively large oblique angle were relatively prone to fatigue fracture. With the increase of the loading angle, the angle between the crack extension direction and the loading direction decreased gradually. The cracks first appeared at the inside lug hole of the tapered lug subjected to the lateral load and the angle between the extension direction and the loading direction was about 45°.