Shock Compression Behavior of Stainless Steel 316L Octet-Truss Lattice Structures

The compressive shock behavior of stainless steel 316L (SS316L) octet-truss lattice structures was investigated through experimental techniques and numerical simulations. Plate impact experiments were conducted at impact velocities of 270-390 m/s on lattice specimens with 5x5x10 unit cell geometries additively manufactured (AM) using direct metal laser sintering. High-speed imaging with digital image correlation was used to extract full-field measurements of particle velocities and define an elastic wave front and a compaction shock front. A linear shock velocity-particle velocity relation was extracted and may be approximated using a slope of one and linear fit constant equal to the crushing speed. The shock velocity-particle velocity relation was used with the Eulerian form of Rankine-Hugoniot jump conditions to develop relations for the stress and internal energy behind the shock; stress increased with relative density and particle velocity and internal energy per unit mass converged to a curve similar to bulk AM SS316L. Explicit finite element analysis using the Johnson-Cook constitutive model demonstrated similar shock behavior observed in experiments. A linear shock velocity-particle velocity relation and corresponding Hugoniot calculations agreed with experimental results.