Shear axial modes in a PCTSCM Part I: Piezoelectric stiffening and selective attenuation

The material properties of a piezoelectric continuously twisted structurally chiral medium (PCTSCM) vary helicoidally along the axial direction. Since the degree of piezoelectric coupling can be engineered to a reasonable extent, PCTSCMs are promising candidates for future transduction devices. In this paper, we implement the quasi-electrostatic approximation for axial propagation modes in PCTSCMs, particularly for those with hexagonal 6mm reference crystal symmetry. Axial propagation of shear modes is affected by piezoeletric stiffening. Axial propagation displays selective attenuation and can be classified into three zones. The zone of selective attenuation can be altered by the degree of piezoelectric stiffening as well as by the spatial frequency of the PCTSCM.