Effect of Bushing Structure on Mechanical Properties and Failure Mechanism of CFRP Laminated Titanium Nail Riveting

In the aerospace field, the riveting process is one of the main methods for connecting the Carbon Fiber Reinforced Polymer/Plastic (CFRP). During the riveting process, components are prone to problems such as damage to CFRP hole walls and reduction in joint strength. To this end, this paper proposes two new bushing structures based on riveting. The riveting damage behavior and mechanical properties of composite materials under three riveting methods: non-bushing, non-boss bushing, and boss bushing were compared. Furthermore, the tensile and hysteretic mechanical properties of CFRP under different riveting structures were studied. The results show that the stress distribution around the hole is more uniform than that of the non-bushing riveting method, and the delamination damage at the hole wall is significantly reduced. In the tensile test, the maximum tensile loads of the non-boss bushing and the boss bushing increased by 2.49% and 5.03% compared to the non-boss bushing schemes. In addition, the tensile failure modes of the three schemes also showed different failure modes due to different riveting forms. The failure mode of the non-bushing riveting scheme is rivet shear failure, and the failure mode of the bushing riveting scheme is rivet pull-off failure. In the hysteretic test, the maximum tensile loads of the non-boss bushing and the boss bushing increased by 5.49% and 12.03% compared to the non-bushing scheme. The failure mode of the three schemes is rivet pull-off failure. The bushing structure not only enhances the connection strength, but also improves the damage to the CFRP hole wall. This study provides a new understanding of the design and optimization of CFRP riveted connection structures.