Novel plate-cell architecture reaches theoretical limit of performance
Researchers have closed-cell plate-nanolattices that are stronger than diamonds in terms of a ratio of strength to density. The performance of this arrangement had been theorized but never experimentally validated until now.
"Previous beam-based designs, while of great interest, had not been so efficient in terms of mechanical properties," said corresponding author Jens Bauer, a UCI researcher in mechanical & aerospace engineering. "This new class of plate-nanolattices that we've created is dramatically stronger and stiffer than the best beam-nanolattices."
According to the paper, the team's design has been shown to improve on the average performance of cylindrical beam-based architectures by up to 639 percent in strength and 522 percent in rigidity.
Cameron Crook, Jens Bauer, Anna Guell Izard, Cristine Santos de Oliveira, Juliana Martins de Souza e Silva, Jonathan B. Berger, Lorenzo Valdevit. Plate-nanolattices at the theoretical limit of stiffness and strength. Nature Communications, 2020; 11 (1) DOI: 10.1038/s41467-020-15434-2
Though beam-based lattices have dominated mechanical metamaterials for the past two decades, low structural efficiency limits their performance to fractions of the Hashin-Shtrikman and Suquet upper bounds, i.e. the theoretical stiffness and strength limits of any isotropic cellular topology, respectively. While plate-based designs are predicted to reach the upper bounds, experimental verification has remained elusive due to significant manufacturing challenges. Here, we present a new class of nanolattices, constructed from closed-cell plate-architectures. Carbon plate-nanolattices are fabricated via two-photon lithography and pyrolysis and shown to reach the Hashin-Shtrikman and Suquet upper bounds, via in situ mechanical compression, nano-computed tomography and micro-Raman spectroscopy. Demonstrating specific strengths surpassing those of bulk diamond and average performance improvements up to 639% over the best beam-nanolattices, this study provides detailed experimental evidence of plate architectures as a superior mechanical metamaterial topology.
