Structure-performance relationships of multi-material jetting polymeric composites designed at the voxel scale: Distribution and composition effects

Multi-material jetting (MMJ) allows for printed parts with intricate distributions of photopolymer materials deposited through hundreds of tiny nozzles at the voxel design scale. In this study, the mechanical tensile performance of various two-material composite designs is compared with respect to various volumetric ratios of two constituent materials, one rigid and strong and the other soft and ductile. Layered samples exhibited convergent, alternating layer failure due to interfacial bonding and fracture mechanisms of the dissimilar materials. To assist with predicting deformation profiles and explaining this behavior, a multilayer composite model was developed. Additionally, newly accessible voxel-scale digital material creation software was used to create custom “digital material” (DM) composites with a greater range of tunable strength, stiffness, and modulus of toughness over multilayer composites and manufacturer preset DM composites. Specifically, custom DMs increased the tunable ranges of ultimate strength and Young's modulus by 25.8 % and 5.5 %, respectively, and the achievable modulus of toughness by 56.3 % over the other composites. This study highlights the benefit of utilizing the full potential of MMJ by creating composite geometries designed at the voxel scale and provides groundwork for future comparative studies where customized voxel-scale material distributions can be tuned to achieve a desired mechanical performance over traditional composite designs.