Sand’s Approach to Yield: How Granular Materials Creep and Fail

Examples of granular materials exist in abundance, from rice and cereal to sand and rocks. These particulate systems seem simple; they consist of dry, rigid grains that interact by contact forces. However, granular materials present many questions to address, such as how force distributes heterogeneously among grains and how flow behavior can readily change between solid-like and fluid-like. In this talk I will illustrate how experimental techniques involving photoelasticity probe this behavior of granular materials down to the scale of a single grain. I investigate the structure and dynamics of granular creep, illuminating signatures of failure through the evolution of the contact force network.