The law of reciprocity in acoustics and elastodynamics codifies a relation of symmetry
between action and reaction in fluids and solids. In its simplest form, it states that the …

Elasticity typically refers to a material's ability to store energy, whereas viscosity refers to a
material's tendency to dissipate it. In this review, we discuss fluids and solids for which this is …

Acoustic resonances in open systems, which are usually associated with resonant modes
characterized by complex eigenfrequencies, play a fundamental role in manipulating …

Willis coupling generically stems from bianisotropy or chirality in wave systems.
Nevertheless, those schemes are naturally unavailable in diffusion systems described by a …

Initially proposed to achieve strong noise isolation levels beyond the mass-density law,
acoustic metamaterials (AMMs) have now overturned the conventional views in all aspects …

Materials made from active, living, or robotic components can display emergent properties
arising from local sensing and computation. Here, we realize a freestanding active …

Willis materials exhibit macroscopic cross-coupling between particle velocity and stress as
well as momentum and strain. However, Willis coupling coefficients designed so far are …

The article reviews general properties of time-varying dispersive materials. We first briefly
discuss different dispersion models that have been proposed in the literature, the role of the …

Willis coupling in acoustic materials defines the cross-coupling between strain and velocity,
analogous to bianisotropic phenomena in electromagnetics. While these phenomena have …

Guided waves, elastic waves propagating through bounded structures, play a pivotal role in
various applications, including ultrasonic non-destructive testing and structural health …