Experimental and numerical investigations on fatigue behavior of aluminum alloy 7050-T7451 single lap four-bolted joints

Xiaomei Liu¹，Hao Cui¹，Shangzhou Zhang¹，Haipo Liu¹，Shujun Li³

1. School of Environmental and Materials Engineering, Yantai University3. Institute of Metal Research, Chinese Academy of Sciences

摘 要：The fatigue behavior of aluminum alloy 7050-T7451 single lap four-bolted joints was studied by highfrequency fatigue test and finite element（FE） methods. The fatigue test results showed that a better enhancement of fatigue life was achieved for the joints with high-locked bolts by employing the combinations of cold expansion, interference fit, and clamping force. The fractography revealed that fatigue cracks propagated tortuously; more fatigue micro-cliffs, tearing ridges, lamellar structure were observed,and fatigue striation spacing was simultaneously reduced. The evaluation of residual stress conducted by FE methods confirmed the experimental results and locations of fatigue crack initiation. The extension of fatigue lives can be attributed to the evolution of fatigue damage and effect of beneficial compressive residual stresses around the hole, resulting in the delay of crack initiation, crack deflection, and plasticity-induced crack closure.

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