Exploring the enhanced energy-absorption performance of hybrid polyurethane(PU)-foam-filled lattice metamaterials

In this study, the experimental and numerical investigations are performed to explore the enhanced energy-absorption performance of hybrid polyurethane(PU)-foam-filled lattice metamaterials subjected to low-velocity impact (LVI). Initially, three types of lattices are prepared by additive manufacturing technique, and then filled with the PU foams using freeze casting technique. Experimental and numerical LVI tests have been performed to characterize the energy-absorption performance of pure and hybrid lattice structures. These experimental and numerical results indicate that the hybrid structures possess the longer elastoplastic and damage evolution stages than the pure ones. The overall absorbed energy of the hybrid structures is distinctly higher than the sum of pure lattices and PU foams, disclosing the enhancement of the energy-absorption capacity induced by the PU-foam-filling. Besides, the pure and hybrid hyperbolic lattice structures exhibit the better energy-absorption capacity than two other types, due to the compression-twist effect. As the foam collapse occurs, the lattice damages are significantly inhibited in the hybrid ones. It reveals that the filled foams protect the embedded lattices via causing foam collapse to dissipate impact energy. Meanwhile, foam-filling prevents the excessive twisting behavior of the hyperbolic lattice and makes the stress distribute more evenly.