Design scheme for lattice structures supporting simultaneous uniaxial static and impulsive loads*

Owing to their ability to provide tunable mechanical responses, additively manufactured lattice materials are frequently 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. In contrast, this work outlines a design scheme for lattice materials which must simultaneously support static loads while enduring high-magnitude impulsive loads. For a class of impulse shapes associated with laser shocks, 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.