Hybrid bonded–bolted composite material interference connections significantly enhance the collaborative load-bearing capabilities of the adhesive layer and bolts, thus improving structural load-carrying capacity and fatigue life. So, these connections offer significant developmental potential and application prospects in aircraft structural assembly. However, interference causes damage to the adhesive layer and composite laminate around the holes, leading to issues with interface damage. In this study, we employed experimental and finite element methods. Initially, different interference-fit sizes were selected for bolt insertion to analyze the damage mechanism of the adhesive layer during interference-fit bolt installation. Subsequently, a finite element tensile model considering damage to the adhesive layer and composite laminate around the holes post-insertion was established. This study aimed to investigate damage in composite bonded–bolted hybrid joints, explore load-carrying rules and failure modes, and reveal the mechanisms of interference effects on structural damage and failure. The research results indicate that the finite element prediction model considering initial damage around the holes is more effective. As the interference-fit size increases, damage to the adhesive layer transitions from surface debonding to local cracking, while damage to the composite matrix shifts from slight compression failure to severe delamination and fiber-bending fracturing. The structural strength shows a trend of initially increasing and then decreasing, with the maximum strength observed at an interference-fit size of 1.1%.

The interfacial contact status of a joint determines the sealing performance of an aircraft hydraulic system, which is influenced by inevitable multiscale assembly errors and joint manufacturing deviations. To address these challenges, a novel geometric analysis model was heuristically created that incorporates assembly and manufacturing-related topographies to accurately estimate the initial relative assembly position of joint surfaces. A microscopic contact model was constructed using the reverse reconstruction approach based on measured surface characteristics. Combining the relative position, a multiscale finite element contact model was generated to investigate the impact of each scale topography on the contact state of the seal ring. The experimental data verified the simulated indentation findings, confirming the model's efficacy in estimating contact status and seal performance characteristics. It is found that the flare angle has a more obvious effect on the contact state of the sealing interface, and a 2° difference in angle under the same load can cause a 28.19% difference in contact area, which greatly affects the sealing performance.