Mechanical Performance of Gomphosis‐Type Fiber Metal Laminates With Meso‐Grooved Interlocking Interfaces

ABSTRACT Shear‐dominated interfacial failure associated with mode II fracture is a critical factor limiting the load‐bearing capacity and crack resistance of fiber metal laminates. In this study, a gomphosis‐type interface strengthening strategy was proposed by prefabricating meso‐grooves on the metal surface, enabling resin infiltration and mechanical interlocking during hot‐press curing. The effects of groove depth on interfacial stiffness, load‐bearing capacity, interfacial damage‐mode evolution, and mode II fracture resistance were systematically investigated using end‐notched flexure tests, geometry‐induced wettability analysis, fracture morphology observation, and an equivalent spring‐mass model. The main contribution of this work is to reveal the groove‐depth‐dependent stiffness‐strength decoupling behavior and to clarify how groove‐induced geometric constraint modifies interfacial slip, crack deflection, and fracture‐energy dissipation mechanisms under shear‐dominated loading. The results show that the gomphosis‐type interface effectively improves the mechanical performance of fiber metal laminates. As the groove depth increased from 0.1 to 0.4 mm, the initial stiffness decreased by approximately 13.4%, whereas the peak load increased by about 35.3%, and the mode II fracture resistance increased from 3.1 to 9.9 kJ/m ² . The optimal performance was achieved at a groove‐depth/metal‐thickness ratio of approximately 20%. Excessive groove depth promoted groove‐root stress concentration and fiber‐involved damage, reducing the beneficial contribution of interlocking.