Rational design and additive manufacturing of grain boundary-inspired, multi-architecture lattice structures

The advent of additive manufacturing has facilitated the design and fabrication of hybrid lattice structures with multiple morphologies. These structures combine multiple distinct architectures into a single structure with an exceptional performance that far exceeds that of each constituting architecture. However, combining strut-based lattices poses serious challenges in establishing effective connections, primarily due to complications in formulating mathematical expressions. Here, we introduce a novel approach, inspired by the connections observed in the grain boundaries of polycrystalline materials, to design the interconnections of hybrid structures. This strategy involves shrinking the unit cell linkage, thereby addressing the difficulty of forming efficient connections at arbitrary spatial interfaces within strut-based lattice structures. We then use the relevant design theories to tune the performance of these connections and simplify the design process for hybrid structures - even for inexperienced designers. Our experimental observations confirm the efficacy of the proposed strategy, bridging the knowledge gap in the design of connected strut-based multi-lattice structures. Furthermore, this approach enhances the design of tailored hybrid structures and fosters the development of metamaterials with advanced, unique functionalities. The proposed approach has important implications for the development of designer materials, with applications in medical devices, (soft) robotics, and implants.