Strain Rate Effect on the Structural Performance of Mathematically Generated Metastructures

Additive manufacturing approaches enable designing and fabricating structures with complex geometries, such as triply periodic minimal surface (TPMS) lattices with unique mechanics. TPMS structures are pursued for impact mitigation for civilian and military applications. Herein, additive manufacturing of TPMS structures (gyroids, Schwarz diamond, and Schwarz primitive) is done using hyperelastic photocurable resin with glass microballoon reinforcements and the strain rate effects on the mechanical responses are investigated. A successful optimization of vat photopolymerization 3D printing is done to realize TPMS structures with modified photocurable resin with up to 20.6 vol% (20 wt%) glass microballoons. An exploratory investigation is performed using a split-Hopkinson pressure bar to test the impact response of bulk samples and TPMS structures. It is found that glass-reinforced hyperelastic resins exhibit favorable mechanical and structural behaviors, motivating comprehensive experimental regimens as a function of strain rates, including quasi-static and low- and moderate-velocity loading scenarios. The results highlight the affinity of gyroid structures to self-contact and relative sliding, enhancing the performance at low strain rates. The primitive TPMS structures outperform the remaining counterparts in the impact loading scenarios based on the structural performance. The outcomes of this research evidence the potential of 3D-printed TPMS structures with glass-reinforced hyperelastic photocurable resins for improved impact efficacy.