Nonreciprocal Wave Propagation in a Continuum-Based Metamaterial with Space-Time Modulated Resonators

Space-time-modulated mechanical systems offer a different paradigm in the design of advanced nonreciprocal mechanical devices. Physically realizing materials with properties rapidly tuned in both space and time, however, presents several challenges. This study introduces an elastic metamaterial with coupling stiffness modulated in space and in time by programmably pumping ac currents into coils. It theoretically and experimentally demonstrates tunable, nonreciprocal propagation of flexural waves on a continuum. This device suggests interesting opportunities in structural dynamics, and in the design of advanced mechanical insulators, diodes, circulators, and topological insulators.