Comparison of the strength of resistance spot-welded, bonded, and hybrid single lap joints: A numerical investigation

• This study investigates the mechanical performance of RSW, ADJ, and hybrid joints. • Investigated spot-weld size and adhesive ductility-brittleness effects. • Adding adhesive layers to hybrid joints boosts energy absorption by 22 %. • Larger welds boost energy absorption 75.5 % and load capacity 53.7 %. • Araldite 2015 absorbs more energy but lacks early failure warning of stiffer adhesives. • Increasing adherend thickness improves hybrid joint performance. Robust and lightweight joining techniques are crucial for good performance and safety in advanced engineering applications, particularly in the automotive and aerospace sectors. While traditional methods such as bolting, riveting, and resistance spot welding have been central to structural assembly, they face limitations under modern engineering demands like higher strength, weight reduction, improved fatigue life and damage tolerance. This study investigates the mechanical performance of resistance spot-welded, adhesively bonded, and hybrid single lap joints, focusing on the effects of spot-weld diameter and the adhesive layer's ductile-brittle properties. The ABAQUS/Explicit finite element program was employed to model three-dimensional adhesively bonded, resistance spot welding, and hybrid (combination of the first two) joints made of advanced high-strength steel (AHSS) DP1000. Cohesive zone elements simulated adhesive damage initiation and propagation as well as the pull-out failure. The models were validated against experimental data from literature. The study examined three adhesives (SikaPower 423 L1, Araldite AV138, Araldite 2015), three spot-welding diameters, and three adherend thicknesses to provide detailed insights for optimizing joint designs, enhancing reliability and durability in complex engineering applications. The results indicate that the hybrid joint employing SikaPower 423 L1 adhesive achieved an energy absorption of 14.4 J, representing a 22 % improvement over the resistance spot-welded (RSW) joint. Notably, the hybrid joint with Araldite 2015 adhesive exhibited the highest energy absorption, reaching 23.1 J—an impressive 96 % increase compared to RSW. Following this, the hybrid joint using Araldite AV138 adhesive demonstrated an energy absorption of 18.1 J, marking a 53 % enhancement over RSW.