Professor Xiaoyu (Rayne) Zheng, Virginia Tech
Printing with Light: Ultralight, Hierarchical Architected Metamaterials
Abstract: Few solid materials exist considerably lighter than water. To decrease the density beyond this point, materials must have a porosity, which generally comes at the cost of a disproportional degradation of other desirable properties. For example, graphene aerogels have among the lowest record densities ~1kg/m3, but their strength have been degraded to tens to hundreds of Pascal (<10-8 of that of graphene). The attainment of low density has come with a price — significant reduction of mechanical properties.
3D architected metamaterials are among the lightest manmade materials created to date yet with exceptional strength and stiffness. These materials are capable of holding more than 160,000 times of their own weight while being as light as a carbon aerogel. Their performance is attributed to the hierarchical layout of structural 3D architectures from nanometers to tens of centimeters and above. I will discuss a suite of scalable additive micro- and nanoscale additive manufacturing technologies that have been developed in our group to enable fast manufacture of these architected materials in polymer, metals, ceramics and nanocomposites. Attention is focused on the exceptional mechanical performance of these micro and nanolattices, including their ultra-high strength, damage tolerance, and stiffness, and examine their potential for multifunctional applications beyond mechanics. The introduction of hierarchical 3D architectures from tens of nanometers to tens of centimeters and above has been transforming our ability to tailor metamaterial properties that break the existing scaling laws between density, strength and toughness in materials.
About: Xiaoyu (Rayne) Zheng has been an Assistant Professor of Mechanical Engineering and directs the Advanced Manufacturing and Metamaterials Laboratory at Virginia Tech since December 2015. He holds an affiliate position at the Macromolecules and Innovation Institute and the Department of Materials Science and Engineering at Virginia Tech. His research interests includes using principles of optics and mechanics to develop scalable, high precision additive manufacturing techniques, metamaterials and their multi-functional applications in material design, mechanics, energy storage and transductions. Prior to joining Virginia Tech, from 2011 to 2015, he had been a Member of Technical Staff and Principle Investigator at DOE Lawrence Livermore National Laboratory, California, where he worked on high volume additive manufacturing initiatives and materials with controlled micro-architectures (DARPA MCMA). He received his Ph.D. degree in Mechanical Engineering from Boston University in 2011 with the Outstanding Dissertation Award. He and his team had developed the world’s lightest materials capable of holding more than 160,000 of their own weight with a mass density as light as aerogels. Zheng has published over 40 journal articles, proceeding papers and book chapters. His work on Micro/nano 3D printing and architected metamaterials has been selected as top 10 innovations of 2015 by MIT Technology Review. He received ICTAS Junior Faculty Award, Inventor’s Award, Director’s Publication Excellence Award at Lawrence Livermore National Laboratory. His work has been widely reported by R&D Magazine, Materials Today, Nano Today, MRS Bulletin, American Physics Society etc.