Active solids: stress reorganisation and response

Initially I will introduce the concept of active matter, that is matter driven out of equilibrium by an internal energy source. In particular I will then focus on active solids. I will present a microscopic model of a disordered viscoelastic active solid, i.e., an active material whose long time behaviour is elastic as opposed to viscous. It is composed of filaments, passive cross-links, and molecular motors powered by stored chemical energy, e.g., actomyosin powered by ATP. Our model allows us to study the collective behavior of contractile active elements and how their interaction with each other and the passive elastic elements determines the macroscopic mechanical properties of the active material. As a result of the (un)binding dynamics of the active elements, we find that this system provides a highly responsive material with a dynamic mechanical response strongly dependent on the amount of deformation.