The effects of structural symmetry of laser‑constructed patterns on the adhesive bonding performance of 6061 aluminum alloy

This study systematically investigates the effects of the rotational symmetry of laser constructed polygonal patterns on the interfacial bonding properties of adhesive joints in 6061 aluminum alloy. Based on the difference in rotational symmetry, triangular, rectangular, and hexagonal morphologies were fabricated via laser surface texturing, and their wettability, surface physicochemical properties, mechanical properties, and bonding strength were evaluated. The results show that, as the symmetry factor n increases from 3 to 6, surface roughness decreases, while wettability, mechanical properties, and chemical bonding at critical anchoring sites improve monotonically, significantly enhancing the adhesion at the bonded interface. Within the selected range, the hexagonal pattern, which possesses the highest rotational symmetry coefficient, exhibits the highest surface free energy (81.21 mJ/m 2 ) and the lowest stress concentration factor K t , leading to uniform stress distribution and a high failure strain (0.061438) and bending moment (2.93°). Accompanied by the formation of Al–O–C chemical bonds, the maximum shear strength of 20.53 MPa was achieved—a 27.5 % increase over the 1000# grinding sample—with cohesive failure. Moreover, thermogravimetric analysis confirms its superior thermal stability (decomposition peaks at 372.66 °C and 452.18 °C, lowest mass loss), reflecting high fracture energy. These results demonstrate that rotational symmetry greatly affected the synergy between mechanical interlocking, stress distribution, and chemical bonding with high-performance adhesive joints, providing new insights for the design of more complex surface textures.