Fatigue crack growth in 1.6‐mm‐thick sheets of aluminium alloy AA2024‐T3 was investigated under very high‐stress conditions using 950‐mm‐wide middle tension (MT) specimens. Experiments were conducted by applying uniaxial load ratios R (0.1, 0.3 and 0.5) with the maximum nominal stress of 120 MPa following conditions relevant for aircraft fuselage structures. The experiments were conducted with digital image correlation to determine loading conditions acting on the crack tip. Stable crack growth rates of up to da/dN > 4 mm/cycle and ΔK > 100 MPa√m were reached, and final crack lengths 2a > 500 mm were obtained. High‐stress intensity factors cause plastic zone sizes that extend up to approximately 100 mm from the crack tip. The da/dN‐ΔK data obtained in this study provide crucial information about the fatigue crack growth and damage tolerance of very long cracks under high‐stress conditions in thin lightweight structures.

中文翻译：

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AA2024-T3薄板材料的高应力疲劳裂纹扩展

使用 950 毫米宽的中等张力 (MT) 试样在非常高的应力条件下研究了 1.6 毫米厚的 AA2024-T3 铝合金板的疲劳裂纹扩展。实验是通过在与飞机机身结构相关的条件下应用单轴载荷比 R（0.1、0.3 和 0.5）以及 120 MPa 的最大标称应力来进行的。实验是通过数字图像相关性进行的，以确定作用于裂纹尖端的载荷条件。达到 da/dN > 4 mm/周期和 ΔK > 100 MPa√m 的稳定裂纹扩展速率，并获得最终裂纹长度 2a > 500 mm。高应力强度因素导致塑性区尺寸从裂纹尖端延伸至约 100 mm。