Maurizio Romeo

Interfacial viscoelastic SH waves

Shear horizontal waves, in the form of transient perturbations, are considered at the interface between two different viscoelastic solids. The admissibility of these interfacial waves is studied via the asymptotic expansion of the Laplace transform of the viscoelastic kernel. The compatibility condition is reduced to a set of algebraic systems which can be solved iteratively to the desired order in the asymptotic expansion. Two classes of solutions are found which correspond to transient waves decaying away from the interface and attenuated along the propagation direction. Numerical examples are given to illustrate the results.

A variational formulation for electroelasticity of microcontinua

The governing equations for a micromorphic theory of electromagneto-elastic dielectrics are derived by a variational formulation. Balance equations and boundary conditions are obtained assuming the internal energy as dependent on macro and micro-strain variables. A micropolar linear model is derived and the evolution equations for dipole and quadrupole are exploited to arrive at an expression for the polarization density. The present model is applied to the simple shear static problem for an isotropic dielectric layer subject to an external field. The resulting shear displacement and electric potential noticeably differ from the classical elastic case.

Electromagnetic field-current coupling in rigid polarized conductors:

A continuum model, based on a theory of electromagnetic media with microstructure, is exploited to deal with rigid conductors endowed with polarization and magnetization. Charge carriers are considered as a continuum superimposed to the microstructured conductor where the density of bound charges depends on the internal degrees of freedom of the continuum particle. The non-linear dynamical model is formulated, deriving the mechanical balance laws that are coupled with the electromagnetic field equations. A reduction to the micropolar linear case is performed in order to analyze admissible solutions in the form of one-dimensional plane waves. Dispersion equations are derived for modes pertaining to longitudinal and transverse fields and the effects of conductivity and polarization are evidentiated. Polariton modes, arising from the dynamics of microdeformation, are also discussed.

A wave splitting approach to thermoelastic pulses in anisotropic media

Abstract Transient wave propagation is considered in a thermoelastic anisotropic medium modelled by means of linear constitutive functionals. The wave splitting technique is exploited to solve a boundary value problem for mechanical and thermal fields. Analytical solutions are derived for the physical setting of crystals at low temperatures. It is found that thermoelastic transient waves amount to the superposition of a fast component which propagates with a speed close to that of sound and a slow component which is identified as the second sound. Purely thermal and purely mechanical boundary pulses are chosen as examples to illustrate the results.