Observing High Strain Rate Compression of Gradient Density Octet Lattices using Ultrafast X-Ray Imaging

Architected materials are a new class of engineered materials with controlled internal structures that give rise to properties that differ or surpass those of their constituent materials. Micro- and nano-structured lattices have demonstrated superior quasi-static mechanical properties compared to traditional materials or composites but, their dynamic mechanical behavior under high strain rate conditions is poorly understood. Here we compressed gradient density octet lattices fabricated using Nanoscribe under high strain rates and observed the deformation behavior using ultrafast X-ray imaging at Argonne National Lab. We used high fidelity hydrocode modeling of the lattices and utilized X-ray imaging to directly relate the measured in-situ compressed lattice to the model predictions for the expected output ramp profile. We observed that the direction of increasing density profile (higher density at the substrate compared to lower density at the substrate) affected the onset of acceleration and the compression profile at the backend of the substrate. We show that micro-architected lattices with smoothly varying density gradients have a great potential for creating tailored ramp compression profiles.<br/><br/>IM release number LLNL-ABS-850153. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.