Elastic nonreciprocity via nonreciprocal hybridization and destructive interference

When a nonreciprocal lattice strongly couples to a reciprocal lattice, it can imbue the reciprocal system with nonreciprocal properties through hybridization. We demonstrate that nonreciprocal hybridization generates nonreciprocity via two mechanisms: first, the formation of a nonreciprocal partial band gap; and second, nonreciprocal destructive interference between two wave modes propagating in the same direction. Critically, for structures with a limited number of unit cells, destructive interference can generate significantly stronger nonreciprocity and attenuation compared to the nonreciprocal band gap in the same system. We use this principle to realize linear and time-invariant elastic nonreciprocity by coupling an elastic waveguide to a nonreciprocal electrical lattice using the piezoelectric effect. By designing the electrical lattice to hybridize with the elastic waveguide, broadband nonreciprocal dissipation is observed in the overall system. We validate the theoretical predictions experimentally, observing a nonreciprocal antiresonance with 7.4 times (17.4 dB) contrast between left-to-right and right-to-left responses at steady state. This result opens alternative research directions by greatly simplifying the realization of nonreciprocal elastic dissipation, paving the way for elastic ``circuits'' that freely manipulate sound and vibration.