Propagation of Floquet–Bloch shear waves in viscoelastic composites: analysis and comparison of interface/interphase models for imperfect bonding

The phononic band structure of waves, which travel though composites, results from the geometric and mechanical properties of the materials and from the interaction of the different constituents. In this article, we study two different models to simulate imperfect bonding and their impact on the phononic bands: (a) imperfect bonding is simulated by introducing an artificial interphase constituent with properties which define the bonding quality; (b) imperfect bonding is described by conjugate conditions in the interface, in which the difference in the displacement is proportional to the interfacial stress. Viscoelastic behavior of the constituents has a crucial influence on the traveling signal, and the wave attenuates with increasing viscosity. We study the interaction of the different bonding conditions and the viscoelastic behavior as well as the impact of such interplay on the wave attenuation and dispersion characteristics of the material.