Quantitative Design and Residual Strength Assessment of Adhesive-Rivet Hybrid Repairs for Perforated Aluminum Alloy...

Perforation damage can significantly reduce the load-carrying capacity of aluminum alloy plates. Adhesive-rivet hybrid repair combines the continuous load-transfer capability of adhesive bonding with the reliable mechanical connection provided by riveting; however, quantitative methods for matching damage size, rivet parameters, and adhesive load-carrying capacity remain insufficient. In this study, perforated 2A12-T4 aluminum alloy plates were investigated. Based on the equal-strength criterion and load-transfer equilibrium, a strength-matching relationship between the adhesive layer and blind rivets was established, and a residual-strength assessment method for the repaired structure was proposed. Two typical two-part epoxy adhesives with different shear strengths, Araldite-2015 and Lord 320/322, which have application backgrounds in aerospace structural joining and repair, were selected. Combined with blind rivets of different load-carrying capacities, they formed strong-adhesive/weak-rivet and weak-adhesive/strong-rivet configurations to investigate the mechanical response under different adhesive-rivet strength-matching conditions. Quasi-static tensile tests, digital image correlation (DIC) measurements, and finite element analyses incorporating a cohesive zone model and a ductile damage criterion were performed to investigate load distribution and failure behavior. The results show that the maximum deviation between the finite element predictions and the experimental failure loads is 5.02%. Before significant adhesive failure, the adhesive layer carries up to 67.25% of the transferred load, indicating a substantial load-sharing effect on the rivets. The hybrid-repaired structures mainly fail along the cross-section through the outermost rivet holes. The proposed residual-strength model shows agreement with the investigated experimental dataset, with a maximum deviation of 6.37%; because the reduction coefficient contains an empirical calibration component, broader predictive applicability requires independent validation. For the six repair configurations, the strength recovery ratios all exceed 74%, the maximum strengthening ratio reaches 55.49%, and the maximum value of the newly proposed repair ratio is 0.48 kN/g. Unlike previous studies that mainly focused on comparisons of joining methods, failure behavior, or individual process parameters, this study establishes a quantitative framework that links damage size and material load-carrying capacity with adhesive-rivet parameter matching and post-repair residual-strength assessment. The proposed method provides theoretical and experimental support for the design and strength evaluation of adhesive-rivet hybrid repairs for perforated aluminum alloy thin plates under fully cured conditions.