Adaptable materials via retraining

Abstract: Elastic metamaterials are often designed for a single permanent function. We explore the possibility of altering a material's function repeatedly through a self-organization, "training" process, controlled by applied strains. We show that the elastic function can be altered numerous times, though each new trained task imprints a memory. This ultimately leads to material degradation through the gradual reduction of the frequency gap in the density of states. We also show that retraining adapts previously trained low energy modes to a new function. As a result consecutive trained responses are realized similarly. We show how retraining can be exploited to attain a response that would otherwise be difficult.