报告内容摘要：

We seek to understand the development of shear and normal stress anisotropies in frictionless granular packings undergoing athermal quasistatic simple and pure shear. We focus on packings of bidisperse disks and circulo-polygons in two spatial dimensions that interact via purely repulsive contact forces. In previous studies, we showed that jammed disk packings form geometric families, for which the packing fraction varies approximately quadratically with strain with positive curvature, for packings that share the same interparticle contact network. We find that packings of circulo-polygons also form geometric families during shear, but they can be either concave up or down. We derive and confirm relations for the shear and normal stress anisotropies in terms of the derivative of the packing fraction with respect to strain for packings of disks and circulo-polygons. We show that disk and circulo-polygons packings develop a nonzero shear stress (with a zero normal stress anisotropy) in the large-system limit when undergoing quasistatic simple shear. In contrast, static disk and circulo-polygon packings possess a nonzero normal stress anisotropy (with a zero shear stress) in the large-system limit when undergoing quasistatic pure shear.

报告人简介：

Prof. Corey O’Hern received his BS from the Department of Physics, Duke University in 1994 and his PhD from University of Pennsylvania in 1999. Before joining the faculty at Yale in 2002, he worked as postdoctoral research associate in physics at the University of Chicago and the University of California, Los Angeles (UCLA). He is now a full professor in the Departments of Mechanical Engineering & Materials Science, Applied Physics, and Physics, Yale University. In 2018, he was elected as a Fellow of the American Physical Society. The O’Hern research group tackles a broad range of fundamental questions in soft matter and biological physics using a combination of theoretical and computational techniques. The group seeks a predictive understanding of glass and jamming transitions of materials, such as granular media, dense colloidal suspensions, and metallic glasses. The group also studies jamming phenomena in biological systems, including tissue and tumor formation, crowding in the cell cytoplasm, and packing in protein cores. He has authored more than 100 manuscripts in peer-reviewed journals, which have been cited over 5700 times, and given more than 150 seminars, colloquia, and presentations at universities and scientific meetings in the US and abroad.
欢迎广大师生光临！