Creep in deformable particles under constant compressive strain

Packings of deformable particle are found in many contexts, ranging from powders to emulsions to foams to biological tissue. These packings show mechanical behavior that cannot be easily understood from the individual particle properties. One of these behaviors is creep: the slow deformation of the packing exposed to a constant stress. We present a study of creep in a model system composed of a packing of hydrogel spheres. Recent work has shown that in such soft particle packings, creep dynamics is set by the confining stress. We use custom rheological tools to drive a packing of submersed particles at a constant shear stress to observe their creep at a given compressive strain. In the phase space of applied shear stress and confining strain, we observe various types of creep behavior and will discuss these in the context of the viscoelastic nature of the particle mechanics.