Experiments on Memory in a Sheared Soft Solid

We consider how a soft 2D jammed material may form memories of past deformation. Our experiments cyclically shear a material made of repulsive particles at an oil-water interface, observing the motion of many particles. Under repeated shearing, the system can evolve toward a ``limit cycle'' in which the same particle rearrangements recur on each cycle of shear; the set of rearrangements is specific to the strain amplitude. We discuss how the material’s history-dependence may be viewed as a memory of the strain amplitude, and we report on progress in describing this behavior, including whether memories of multiple strains may coexist.