Effect of bio-mimicked surface texturing on the shear strength of additively manufactured metal single-lap joints: An innovative approach

Abstract

In this paper, we investigate the mechanical performance of metal single-lap joints featuring bio-mimicking surface textures. The inspiration for the surface textures was the foot and toe of the gecko, a creature whose ability to climb smooth shear surfaces is attributed to the meso- and micro-structures of its feet. Three surface textures were investigated: a hexagonal texture based on the central region of the foot, a lamellae-like texture based on the toe, and a mixed texture of both. Metal adherends with these textures were produced using the laser powder bed fusion (LPBF) additive manufacturing method. Finite element analysis was performed to examine the influence of surface texture on stress distribution in the adhesive layer, while mechanical testing was used to determine joint strength and failure mode. Compared to the as-printed surface texture, bio-mimicking surface textures improved the wettability of the bonding surfaces, and significantly improved the lap shear strength of the joints. Mechanical interlocking due to surface texture was more effective than the increase in bonding surface area in enhancing joint strength. The bio-mimicking textures improved the damage tolerance capacity of the joints by reducing local stress concentrations at the overlap edges of the adhesive layer and ensured that the adhesive failure type was mixed mode due to the mechanical interlocking effect. The presented novel bio-mimicked surface texture method offers promising results for both industrial applications and scientific studies.