An interface-level adhesive–friction model for hybrid-bonded joints: energy-consistent coupling and validation

Hybrid-bonded (HB) adhesive joints can retain a non-negligible load after peak because contact – friction is activated by clamping or surface roughness. Existing models either require explicit hardware (anchors/bolts) or risk double-counting energy when friction is superposed on adhesive fracture. This study proposes an interface-level adhesive – friction framework, implemented via a cohesive-zone model (CZM), that reproduces hybrid-bonded effects without explicitly modelling anchors. The tangential adhesive response follows a baseline-removed trilinear traction – separation law (i.e. the elastic toe is excluded from the fracture-energy accounting), while a spatially localised frictional branch acts in parallel with a pressure-dependent threshold and optional pre-compression enhancement. Mixed-mode evolution uses the Benzeggagh – Kenane criterion, and opening – closure laws govern post-failure contact. A single low-torque specimen calibrates the adhesive channel once; transfer across torque levels updates only the friction plateau amplitude. Validation against published single-shear FRP – concrete joints reproduces the peak load, post-peak shape, and late retention. Ablation that removes the friction branch eliminates the sustained-load tail, isolating friction’s role. The formulation is compact, energy-consistent, and immediately usable for design studies of HB layouts and torque – retention relationships.