Impact response of additively manufactured density-graded open-cell foams

Additive manufacturing has made it possible to fabricate materials that were unachievable with traditional methods. This study focuses on understanding the deformation behavior and energy absorption mechanics of additively manufactured cellular materials with gradually varying densities. Foams have unique deformation behavior due to their intricate topology and composition, resulting in excellent energy dissipation capability. Varying the density can significantly influence their deformation response and improve energy absorption and impact resistance. Voronoi tessellation is employed to model the foams, as it effectively captures the cell morphology in foam structures and produces stochastic cellular topologies accurately. Resin-based additive manufacturing techniques are employed to fabricate cellular materials with varying density configurations for low-velocity and high-velocity impact experiments. The study demonstrates that density-graded foams effectively dissipate a broad spectrum of impact energies, surpassing uniform counterparts by transmitting reduced stress, especially at lower energy levels. This characteristic enhances their suitability for advanced energy absorption applications. The results also show that at high impact velocities, the direction of density gradation influences energy dissipation and peak stress transmission.