Insight into the coordinated jetting behavior in periodic lattice structures under dynamic compression

Abstract

Architected lattices are gaining prominence for structural applications as additive manufacturing technologies mature. Emergent behavior, such as material jetting and wave propagation, arising from the open architecture has been observed under dynamic loading conditions. The origin of the observed jetting and how it might come about across a broad spectrum of lattice types, material compositions, length scales, and dynamic loading conditions is still an open question. The jetting behavior due to lattice structures was studied through a series of dynamic compression plate impact experiments with in situ x-ray imaging. The role of the impact conditions, the lattice spacing, the lattice architecture, and the lattice base material is explored in the context of promoting or suppressing jet formation. A transition from lattice-led to impactor-led jetting is observed above a certain impact threshold. Complementary direct numerical simulations were also performed to compare with the experiments, to study the underlying stress state giving rise to jetting, and to provide insight into conditions not accessed experimentally. We present a geometric argument on the competitive process leading to lattice and/or impactor jetting which incorporates base material properties, the periodicity of the lattice, and basic tunable length scales of the lattice. Using two-dimensional calculations, we further look at how tuning of a single parameter of the studied systems changes the observed jetting transition.