Advancing 4D printing through designing interlocking blocks: enhancing deformation uniformity in active composite structures

Interlocking assemblies have been explored to address large assembly and complex parts and are now integral to additive manufacturing (AM) for creating objects with dissimilar materials and multiple properties. 4D printing technology, which combines smart materials (SMs) with AM, aligns with this approach by enabling the creation of objects that can change shape or properties when exposed to external stimuli. As 4D printing trends towards strategically arranging active and passive materials for improved control and performance, challenges arise due to the limited compatibility of existing 3D printers with the required SM properties. To address this issue, interlocking blocks of dissimilar materials can be printed and then assembled into a desired shape. This work aims to generalize the applicability of the interlocking block assembly approach. This will be achieved by improving the deformation uniformity in a 4D multi-material interlocked assembly. This paper also addresses limitations that can occur due to the interfaces between interlocking blocks, such as lack of deformation and contact continuity. Thus, it will be a question of customizing the shapes of the blocks in the early stages of assembly generation, considering SMs and their potential transformations. Finally, this approach is illustrated with an example, shedding light on the practical implications.