Impact loading of additively manufactured metallic stochastic sheet-based cellular material

The mechanical response of additively manufactured sheet-based stochastic cellular materials under impact loading was investigated in this work. Samples with four different relative densities (13%, 16%, 19%, and 21%) were fabricated out of 316 L stainless steel using the powder bed fusion (PBF) additive manufacturing (AM) technique. The samples were then tested under quasi-static and dynamic (impact) compressive loading conditions to evaluate their mechanical behavior. All analyzed samples showed a similar progressive plateau stress behavior at all analyzed strain rates. The Crash Force Efficiency (CFE) values of samples at analyzed strain rates were in the range of 67–70%, indicating the uniformity of their mechanical response, which is a vital application feature. The samples exhibited excellent Specific Energy Absorption (SEA) capacity ranging between 5 and 9.2 J/g in the quasi-static deformation mode while achieving up to 35 J/g in the shock deformation mode. Thus, the proposed design approach has great potential for impact and blast mitigation applications. The first and second critical loading velocities of analyzed samples are proportional to the relative density and are in the range of 25–32 m/s and 43–56 m/s, respectively. Minor strain rate hardening was observed in quasi-static deformation mode, while a significant strain rate hardening was observed in shock deformation mode achieved by powder gun testing. The developed and validated computational models offered a more detailed analysis of the deformation mechanism and provided means to predict the sample's behavior at very high strain rates.