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 …

Metamaterials are rationally designed composites aiming at effective material parameters
that go beyond those of the ingredient materials. For example, negative metamaterial …

Acoustic metasurfaces derive their characteristics from the interaction between acoustic
waves and specifically designed materials. The field is driven by the desire to control …

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 …

Recent advances in gradient metasurfaces have shown that by locally controlling the
bianisotropic response of the cells one can ensure full control of refraction, that is, arbitrarily …

Acoustic metasurfaces are at the frontier of acoustic functional material research owing to
their advanced capabilities of wave manipulation at an acoustically vanishing size. Despite …

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 …

Non-Newtonian liquids are characterized by stress and velocity-dependent dynamical
response. In elasticity, and in particular, in the field of phononics, reciprocity in the equations …

Metasurfaces, the ultra-thin media with extraordinary wavefront modulation ability, have
shown great promise for many potential applications. However, most of the existing …

Willis fluids, or more generally Willis materials, are homogenized composites that exhibit
coupling between momentum and strain. This coupling is intrinsic to inhomogeneous media …