In most industrial applications, adhesive joints experience impact fatigue loads in service. The energy of each impact is too low to cause joint failure. Although the repetitive impacts usually do not apparently affect the joints, they can significantly reduce the strength of adhesively bonded structures. Accordingly, understanding the effect of impact fatigue on the residual strength of the bonded components is crucial in real applications. This study deals with this issue where the effect of impact fatigue on the residual static strength of single lap joints is analyzed. To achieve this, the manufactured single lap joints were categorized into four different groups. Group 1 joints were tested under static loading conditions. Joints in group 2 were tested under impact to obtain the impact strength of the single lap joints. To analyze the impact fatigue life of the joints, the single lap joints in group 3 were tested under cyclic impact at different energy levels until failure. To investigate the effect of impact fatigue on the residual static strength of the joints, single lap joints in group 4 were tested under a specific number of impact cycles followed by a static tensile test. Using microscopic analysis, the fracture surfaces of the tested specimens were analyzed. The results showed that cracks initiate from the middle of the bonded area as a result of cyclic impact stress waves. Then, by increasing the number of impacts, a large number of cracks nucleate from the edges of the joints and grow along the width to the middle of the overlap. A 3D finite element method was employed to analyze the stress distribution along the bondline under impact loads.

在大多数工业应用中，粘合接头在使用中会承受冲击疲劳载荷。每次撞击的能量过低，不会导致关节故障。尽管重复冲击通常不会明显影响接缝，但它们会大大降低粘合结构的强度。因此，在实际应用中，了解冲击疲劳对粘结部件残余强度的影响至关重要。本研究针对这一问题进行了分析，分析了冲击疲劳对单搭接接头残余静强度的影响。为此，将制造的单膝关节分为四个不同的组。第1组关节在静态载荷条件下进行测试。在冲击下测试第2组的关节，以获得单膝关节的冲击强度。为了分析关节的冲击疲劳寿命，对第3组的单膝关节在不同能量水平下的循环冲击下进行了测试，直到失效。为了研究冲击疲劳对接头残余静态强度的影响，在特定的冲击次数下对第4组的单搭接接头进行了测试，然后进行了静态拉伸试验。使用显微镜分析，对测试样品的断裂表面进行分析。结果表明，由于周期性冲击波的作用，裂纹从结合区的中间开始。然后，通过增加冲击次数，大量的裂纹从接缝的边缘成核，并沿宽度方向延伸到重叠的中间。采用3D有限元方法分析了冲击载荷作用下沿粘结线的应力分布。