Shear-induced Rigidity in Athermal Materials
- Event time: 2:00pm
- Event date: 24th March 2016
- Speaker: Balbul Chakraborty (Brandeis University)
- Location: Room 2511, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB
The ability to resist small shear stresses is what distinguishes a solid from a liquid. This shear-rigidity is associated with broken translational symmetry. Most solids flow when they are sheared beyond a certain limit: the yield stress. It is not usual to associate shearing with increasing the rigidity of a fluid or solid. In athermal materials that are made up of macroscopic particles such as granular materials or dense suspensions, shear can actually induce solidification or a discontinuous increase in the viscosity. In this talk, I will explore the origin of these rigidity transitions: I will show that friction plays a large role in stabilizing these rigid states, and argue that we need a paradigm shift to understand systems in which forces become independent dynamical variables. I will show that shear-induced rigidity is associated with a broken symmetry but in a space that is not characterized by positions and momenta but by forces.
This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..