3D lattice structures at the interface of hybrid metal–SMC composite joints: Effect on joint strength

In the context of lightweight design, particularly in the automotive and transportation sectors, increasing attention is being devoted to multimaterial design strategies, in which component performance is optimized through the combined use of different materials. Within this framework, composite materials are increasingly adopted, often in combination with metallic components. Among the various types of composite materials, Sheet Moulding Compounds (SMCs) are widely used for manufacturing components that require a suitable balance between mechanical performance, cost efficiency, and production speed. However, the structural joining of these components to metallic parts remains a critical issue due to the limited strength of the metal–composite interface. Recent studies have demonstrated that interfacial strength can be significantly enhanced through the introduction of lattice structures at the interface, which are infiltrated by composite fibers during the compression moulding process. The present work aims to investigate the ability of the fibers to infiltrate such lattice structures as a function of selected geometrical parameters, with the objective of maximizing joint strength. Metal–composite joints featuring different interfacial lattice configurations will be manufactured. The effectiveness of the infiltration process will be assessed through microscopic observations of specimen cross-sections as well as through mechanical pull-off tests. The expected outcome of this study is the identification of the most influential geometrical parameters for optimizing joint strength and the quantification of the performance improvement achievable compared to conventional joints employing state-of-the-art surface preparation techniques.