Density-strength tradeoff appears to be an inherent limitation for most materials and therefore design of cell topology that mitigates strength decrease with density reduction has been a long-lasting engineering pursue for porous materials. Continuum-mechanics-based analyses on mechanical responses of the conventional porous materials with bending-dominated structures often give the density-strength scaling law following the power-law relationship with exponent of 1.5 or higher, which consequentially determines the upper bound of the specific strength for a material to reach. In this work, we present a new design criterion capable of significantly abating strength degradation in lightweight materials, by successfully combining size-induced strengthening effect in nanomaterials with architectural design of cellular porous materials. Hollow-tube-based 3D ceramic nano-architectures satisfying such criterion were fabricated in large area using Proximity field nano-Patterning (PnP) and atomic layer deposition (ALD). Experimental data from micro-pillar compression confirmed that the strengths of these nano-architectural materials scale with relative densities with power-law exponent of 0.93, hardly observable value in the conventional bending-dominated porous materials. Our discovery of new density-strength scaling law in the nano-architectured materials will contribute to creating new lightweight structural materials attaining unprecedented specific strengths overcoming the conventional limit.
Dongchan Jang received the Ph.D. and B.S. degrees in Materials Science and Engineering from the University of Michigan – Ann Arbor and Seoul National University, respectively. From 2008 to 2013, he worked as a postdoc in the Department of Applied Physics and Materials Science at California Institute of Technology. He joined the Department of Nuclear and Quantum Engineering at Korea Advanced Institute of Science and Technology (KAIST) in 2013 as an assistant professor and promoted to associated professor in 2018. His research interests include nanomechanics, focused on understanding mechanical behavior at the nanoscale, and its application for structural and functional materials.
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2005 Mechanical Engineering Lab, University of Illinois at Urbana-Champaign, Urbana, IL