Numerical and experimental analysis of shear strength on SLM 3D-printed stainless-steel bonded joints enhanced by bio-inspired surface pattern

The performance of adhesive joints is significantly influenced by the surface texture of the adherends, making texture a crucial factor in their analysis and optimization. Existing literature on numerical modeling of bonded joints predominantly focuses on smooth surfaces, often neglecting the impact of surface patterns. As a result, there is limited understanding of how complex surface textures affect joint performance. Advanced surface textures, such as those inspired from biomimetic systems, have the potential to enhance joint strength. This study addresses this gap by developing two numerical models: one representing a smooth surface (without-texture) and another incorporating a biomimetic fish-scales (FS) texture. The models use Cohesive Zone Modeling with a local approach to simulate the effects of surface texture and adhesive behavior on block-shear joint performance. These models were validated through experimental block-shear tests on P1000 (polished with 1000-grit abrasive paper) and FS-textured stainless-steel joints. Experimental results demonstrated that the FS texture significantly improved joint strength by approximately 44% compared to the P1000 surface. This enhancement is attributed to better adhesive anchoring and extended contact area. Numerical results indicated that the model without-texture exhibited significant stress concentrations at the edges of the overlap, suggesting failure initiation in these regions. However, the FS texture caused repetitive stress peaks along the overlap, and the vertical walls of this texture effectively hindered crack propagation at the interface. Additionally, both models accurately predicted the maximum shear load and failure modes of the P1000 and FS bonded joints, demonstrating good agreement with experimental results, particularly for the hyper-elastic adhesive behavior.