On the Interfacial Bonding Strength Formation in Overmolded Thermoplastic Composites: An Integrated Experimental and Numerical Investigation

ABSTRACT Understanding interfacial bonding strength formation mechanisms in overmolded hybrid composites is critical for designing high‐performance structural components, as bond integrity governs overall structural performance. This work investigates interfacial bonding mechanisms of overmolded thermoplastic composites. An approach integrating experiments with a predictive framework incorporating crystallization kinetics into fusion bonding theory was employed. The results reveal that interfacial strength is governed by two coupled mechanisms: multi‐scale mechanical interlocking and polymer healing with crystallization effects, which are influenced by material, surface, process, and geometric parameters. Framework validation demonstrated the critical role of polymer healing with crystallization effects in thermally driven phenomena. Furthermore, integrated analysis of simulation and experimental results revealed that for geometrically complex parts, macro‐scale pressure‐induced mechanical interlocking can be the dominant mechanism compared to molecular‐level healing. This study provides mechanistic insight and a validated numerical tool for the design and optimization of overmolded thermoplastic composites.