The effects of hybrid design and post-curing time on the mechanical performance of 3D printed lattice structures

To overcome the trade-off between strength and energy absorption capacity inherent in conventional single-topology lattices, a novel hybrid lattice structure, SC-Flu, combining SC (simple cubic) and Flu (fluorite) topologies, was proposed and fabricated using VPP (vat photopolymerisation) technique for its high manufacturing precision. Meanwhile, the effects of hybrid ratio and post-curing time on the compressive stress–strain curves, deformation mechanisms, and mechanical properties of the designed hybrid lattice structures were explored and discussed. The results indicate that adjusting these parameters of the hybrid structure enhances its specific energy absorption (SEA) up to 5.76 J/g by shifting from brittle to progressive failures, which is 3.03 and 1.56 times higher than that of SC and Flu lattices. While extended post-curing improves stiffness and strength, excessive post-curing reduces crushing force efficiency (CFE) by over-strengthening lattice units, as demonstrated by mechanical tests with varying post-curing times. Therefore, achieving the exceptional mechanical performance of SC-Flu requires careful adjustment of design and process parameters to establish an optimal balance between SEA and CFE. Simulations have been conducted and support the experimental findings regarding deformation mechanisms and elastic modulus. Overall, the enhanced and adjustable mechanical response of the hybrid lattice structures was achieved through integrated design and fabrication.