Laser-induced surfaces biomimetic texturing for high-strength GFRTP/Al alloy joints: Analysis of failure modes and strengthening mechanisms

Metal-thermoplastic composite hybrid structures are increasingly required in lightweight engineering, whereas their reliability is often restricted by weak interfacial bonding. In this work, laser-induced surface texturing was applied to 5083 aluminum (Al) alloy to improve the hot-pressed joining performance with glass fiber reinforced thermoplastic composite-PA6 (GFRTP). Four surface textures, including square, rhombus, honeycomb, and fishbone patterns, were fabricated and systematically compared. The effects of surface morphology, wettability, interfacial infiltration, chemical bonding, and fracture behavior on joint strength were investigated. Laser texturing significantly increased the surface roughness and improved the wettability of the aluminum alloy, which promoted the infiltration of molten PA6 into the grooves and formed mechanical interlocking. XPS analysis confirmed the formation of C-O-Al bonds at the interface, indicating the contribution of chemical bonding. Compared with the untreated joint, all textured joints exhibited higher tensile-shear strength. The fishbone-textured joint achieved the highest strength of 23.12 MPa, which was 2.59 times that of the untreated joint. Fracture morphology and finite element analysis indicated that biomimetic textures promoted stress redistribution and crack deflection, leading to a higher proportion of resin cohesive failure. These results suggest that laser-induced biomimetic texturing is an effective strategy for strengthening GFRTP/Al alloy joints.