3D printed, dissolvable molds for the fabrication of geometrically complex, elastomeric energy absorbers

Elastomeric, architected energy absorbers are fabricated by fused filament fabrication (FFF) of dissolvable molds, casting and curing elastomeric resins in the mold cavities, and then dissolving the mold. Multiple mold materials and dissolution solvents are considered, with water-soluble, butenediol vinyl alcohol copolymer (BVOH) molds down selected based on compatibility and dissolution rate studies. A diverse set of lattices, springs, and generalized cylindrical shells are fabricated using cast silicone and urethane elastomers with durometers from 20A to 60D, as well as a foamed elastomer lattice and a glassy epoxy lattice. The use of vacuum during casting enables fine features with high geometric accuracy. Comparisons between cast springs and elastomeric springs fabricated directly via FFF show the superior geometric resolution, and mechanical property space, available using this casting approach. Quasistatic and dynamic compression are performed demonstrating a wide range of mechanical responses, including high energy absorption efficiency. Additional hybrid lattices are fabricated using two different polymers within a single, interlocked structure. The results of this study demonstrate that FFF of dissolvable molds can be used to fabricate complex geometry energy absorbers over a wider range of material properties and chemistries, and with superior feature resolution, compared to the direct FFF fabrication of such structures.