Spatially-graded 3D-printed viscoelastic truss metamaterials for impact trajectory control and energy absorption

• Demonstrated superior energy absorption capabilities in both 2D and 3D spatially-graded truss-based metamaterials. • Experimental and numerical techniques confirmed the efficiency of periodic viscoelastic trusses in dissipating energy. • Spatially graded viscoelastic lattices in 2D and 3D showed enhanced impact mitigation by redirecting the trajectory. • The combined choice of base material and metamaterial design enables optimized energy absorption under varying impact scenarios. • Breakthrough in tailoring lightweight materials for targeted impact functionality achieved through innovative metamaterial design. This study demonstrates that two- and three-dimensional spatially graded, truss-based polymeric-material metamaterials can be designed for beneficial impact mitigation and energy absorption capabilities. Through a combination of numerical and experimental techniques, we highlight the broad property space of periodic viscoelastic trusses, realized using 3D printing via selective laser sintering. Extending beyond periodic designs, we investigate the impact response of spatially variant viscoelastic lattices in both two and three dimensions. Our result reveal that introducing spatial variations in lattice topology allows for redirecting of the impact trajectory, opening new opportunities for engineering and tailoring lightweight materials with target impact functionality. This is achieved through the combined selection of base material and metamaterial design.