Assessing the Design Space for Architected Materials in Extreme Loading Scenarios

Owing to the tunability of mechanical response for structural applications, additively manufactured lattice structures are increasingly being studied to elucidate their response to static and dynamic loads. However, these roles are typically in opposition: static loads must be supported sufficiently far away from the onset of buckling or yielding, whereas dynamic loads are typically ameliorated by crushing of the lattice, which provides excellent energy-absorption due to the large plastic deformation accompanying densification. Moreover, emergent behavior, such as material jetting and elastic wave propagation, arising from the open architecture has been observed in situ under dynamic loading conditions. In this work we will outline a design scheme for lattice structures that must simultaneously support static loads while enduring high-amplitude impulsive loads. For a class of impulse shapes associated with laser-based shock compression, our key findings show that the static and dynamic responses of the lattice can be uncoupled and linked by a strength model that accounts for variability in the additive manufacturing process. Moreover, costly global search optimization can be replaced by sequential one-dimensional optimization following the direction of the wave propagating through the lattice. The design rules developed in this study expand the domain of applicability of lattice structures to challenging dual-loading regimes spanning decades of strain rates.<br/>This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.