Measuring Creep and Stick-Slip Behavior in 2-Dimensional Photoelastic Granular Medium

We report on an experimental study of creep and stick slip in a 2D granular medium. In particular, we study how the accumulation of material in front of the slider after slider motion affects its stick slip dynamics. To do so, we probe the position and acceleration of a slider resting on a 2D layer of photoelastic particles. We either apply a constant force to the slider, or we drag the slider across the particles at a constant rate. The resulting motion of the slider is creep like with stick-slip features. The photoelastic particles beneath the slider allow us to record the structure and dynamics of the forces inside the granular layer that resist motion of the slider. Our goal is to identify features in both internal stress and structure of the granular layer the can serve as precursors for slip events.