Abstract In this study, the effects of patch shape on the performance of bonded composite repairs on aircraft structures are investigated using experimental and numerical approaches. Fatigue tests under constant amplitude loading, with a positive stress ratio, are performed on V-notch cracked specimens using two aluminum alloys, 2024-T3 and 7075-T6 that are repaired with bonded carbon/epoxy patches. Three composite patch shapes are used: rectangular, trapezoidal, and triangular. Left- and right-oriented triangular patch shapes are used to analyze the effects of the patch orientation on the repair efficiency. Numerical models are built with these patch shapes and orientations. The stress intensity factors and adhesive stresses are computed to numerically evaluate the repair performances obtained with the different patch shapes and orientations. The experimental results demonstrate that rectangular patches provide the most efficient repair, whereas the triangular shape with a left-orientation may lead to catastrophic results, particularly with the 2024-T3 aluminum alloy. The numerical results concur with the experimental observations.

中文翻译：

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不同形状单面复合补片修复的铝板疲劳裂纹扩展

摘要 在这项研究中，使用实验和数值方法研究了补片形状对飞机结构粘合复合材料修复性能的影响。使用两种铝合金 2024-T3 和 7075-T6 对 V 型缺口裂纹试样进行了恒幅载荷下正应力比下的疲劳测试，这些铝合金用粘合碳/环氧树脂补片修复。使用了三种复合贴片形状：矩形、梯形和三角形。使用左右方向的三角形补片形状来分析补片方向对修复效率的影响。数值模型是用这些面片形状和方向构建的。计算应力强度因子和粘附应力以数值评估不同补片形状和方向获得的修复性能。实验结果表明矩形补片提供了最有效的修复，而具有左方向的三角形可能会导致灾难性的结果，特别是对于 2024-T3 铝合金。数值结果与实验观察一致。