Enhancing adhesive joint strength through interlocking design: experimental and FE analysis of 3D-printed PA12 structures

This study investigates the mechanical performance of adhesively bonded single-lap joints manufactured from PA12 using the Multi Jet Fusion additive manufacturing (AM) process. A modified Single Lap Adhesive Joint (SLAJ) configuration is proposed by introducing square and circular interlocking patterns within the bonded region to enhance load transfer and joint integrity. The experimental program includes tensile and bending tests conducted on conventional SLAJ, square interlocking (S-SLAJ), and circular interlocking (O-SLAJ) specimens bonded using Araldite 2015 adhesive. The experimental results indicate that the S-SLAJ configuration exhibits consistently higher average load-carrying capacity and energy absorption compared to the conventional SLAJ and O-SLAJ configurations. Failure mode observations further reveal a transition from interfacial debonding to adherend fracture for the S-SLAJ specimens, suggesting improved mechanical interlocking and load redistribution. Finite element analyses are employed to examine stress distribution and load-transfer characteristics, highlighting localized stress concentrations associated with the interlocking geometries. The combined experimental and numerical findings demonstrate that the incorporation of square interlocking patterns into SLAJ designs is associated with improved mechanical performance in adhesively bonded joints fabricated via AM, offering useful insights for the design of advanced bonded structures.