A dynamic model to study shear vertical waves in laminated coupled
electro-mechanical materials is proposed. The mechanical imperfections at the
interface between two materials or phases that constitute an heterogeneous medium
are considered. The behavior of vertical transverse waves is analyzed by
considering two types of imperfect contact. On the one hand, imperfect
contact is taken into account through the motion of layers in the perpendicular
direction to the interface. On the other hand, imperfect contact is considered
through the motion of layers in a tangential direction to the interface. The
layers are coupled through a spring obeying Hooke’s law. The degree of
imperfection is incorporated through the magnitude of the spring’s elastic
constant in both scenarios. The stress is proportional to the jump of the
displacement vector at the layer interface and to the magnitude of the spring’s
elastic constant. Dispersion relations for different volumetric fractions of the
piezoelectric phase and different degrees of imperfection are obtained. Crossover
regions are observed in the dispersion curves. Changes in the oscillation
modes could be identified through the material displacements in these regions.
Displacements within the composite material, used to describe the nature of the
oscillations, are illustrated in some cases. Additionally, the perfect contact case is
reproduced by solving the proposed model for large values of the spring’s
elastic constant, showing a good agreement when compared with the solutions
to models proposed by other authors. A comparison between theory and
experimental results for the electromechanical coupling factor is presented. Finally,
the experimental data for the coupling factor can be better explained by
including the degree of imperfection through the model proposed in this
work.