Optimizing Infill Patterns for Enhanced Durability and Resilience in Direct Ink Writing-Additive Manufacturing of Silicone Elastomers

This study investigates the influence of internal infill geometry and density on the mechanical and rheological behavior of 3D-printed silicone structures fabricated using direct ink writing. Test samples with three different infill patterns (linear, triangular, and honeycomb) and four infill densities (55%, 70%, 85%, and 100%) were manufactured and evaluated through rheological creep–recovery analysis, static tensile and compression tests, and cyclic compression loading. The results demonstrate that both geometry and infill degree significantly affect the rheological and mechanical properties, such as static and cyclic compressive tests of the printed structures. Linear infill exhibited the highest compressive strength at 85% density and maintained favorable short-term stability during initial cyclic loading. Triangular patterns displayed significant sensitivity to infill density, with distinct stiffness characteristics, while honeycomb structures offered a balanced trade-off between density and mechanical response. Microscopic observations confirmed that print path quality and structural continuity correlate with the mechanical properties. The findings underscore the importance of tailored infill design in optimizing the functional performance of silicone-based components for applications such as orthotic insoles, soft robotics, and cushioning systems.