A systematic review on interlocking structures to enhance dissimilar materials joining by additive manufacturing

Multi-material systems are increasingly pursued to meet industrial demands for lightweight, high-performance structures. However, reliable joining remains critical. In recent years, mechanical interlocking has emerged as a promising strategy to overcome limitations of conventional joining methods such as adhesive bonding, mechanical fastening, and welding. By exploiting the geometric freedom of Additive Manufacturing (AM), interlocking structures can be directly integrated into the interface, enabling new opportunities for multi-material integration. Yet, the literature remains fragmented and lacks transferable design principles. This study reframes AM-enabled interlocking as a design-driven interface strategy and, through a PRISMA-guided literature review, introduces a unified design-material-process-performance mapping of the field. Interlocking structures are classified across scales as micro-features, macro-pins, and macro-lattices, and further interpreted through a common set of mechanism-based descriptors. These design categories are then examined alongside dominant material combinations, AM and joining processes, reported mechanical response and failure modes. Sector-specific requirements in aerospace, mobility, biomedical, robotics, and electronics applications are mapped onto the proposed framework, and the main barriers to industrial uptake - lack of standardization, limited non-destructive inspection, scalability, and sustainability - are translated into concrete research directions.