Microscale damage modeling of bolt-hole contact interface during the bolt installation process of composite structure

During the interference-fit joining process of composite bolted structure, the bolt-hole contact interface would form naturally. Understanding the microscale damage mechanism of bolt-hole contact interface is crucial for guarantying load bearing and sealing performance of the composite bolted structure. In this paper, a microscale finite element model was proposed to model the damage behaviors of the bolt-hole contact interface during the bolt installation process. The micro rough characteristics of composite hole-wall surface, bolt surface and bolt coatings were explicitly considered and modeled. The damage initiation of the composites and bolt (including coatings) were calculated by the modified 3D Hashin criterion and von Mises criterion. The proposed microscale model was validated by comparing the load–displacement curve and damage modes with experiments. The results show that the damages primarily occur on the composite hole-wall and bolt coatings. The damage of coatings is primary caused by the squeezing and friction. The damage ratio of coatings is approximately linear positive related to the interference-fit size. The proposed microscale model not only has the potential application for the prediction of microscopic damage, but also for the formation of leakage channel and the protection of corrosion location.