Seminars

Abstract: Poking and bulging have been standard methods for characterizing the mechanics of thin solids including biological, metallic, and elastomeric membranes, as well as emergent atomically thin 2D materials. We call the poked and bulged thin solids tents and bubbles, respectively. Recently, 2D material bubbles and tents have also seen a surge of interest in the field of condensed matter physics, where the mechanical strains were leveraged for the discovery of new physics and quantum applications. The deterministic control of these experiments brings the necessity to elucidate the geometry and deformation regarding 2D material bubbles and tents as well as their controlling parameters. However, there exist significant gaps between recent experimental observations and theoretical understanding of these systems, particularly on the role played by the atomic smoothness of 2D materials. A concrete example is given by the radial wrinkling instabilities that could be observed at the bubble/tent edges but have been prohibited by previous modeling with clamped boundary. This dissertation focuses on the modeling of 2D material bubbles and tents via a collection of problems in this area, with a particular emphasis on the previously overlooked role of the shear at the atomic-level interfaces. We reveal how the elasticity of the 2D material, together with its adhesive and shear interactions to the substrate, selects the mechanical deformation and geometry of those bubbles and tents (including the extent of elastic instabilities). With these understandings, we discuss a number of useful implications for the fundamental elasticity and interface metrology of 2D materials as well as the rational design of bubbles and tents for a range of applications with the instabilities being either avoided or exploited.

Bio: Zhaohe Dai is a Ph.D. candidate in Nanshu Lu group in Engineering Mechanics. Mr. Dai received his B.S. degree in Theoretical and Applied Mechanics from the University of Science and Technology of China in 2013 and M.S. degree in Solid Mechanics from the Institute of Mechanics in 2016. His research is concerned with the mechanics of 2D materials and their interfaces, which is generously supported by US NSF (Grant No. 1351875; PI: Nanshu Lu), UT Austin University Graduate Continuing Fellowship, and Global Research Fellowship.