Axial propagation in piezoelectric, continuously twisted, structurally chiral mediums

Axial propagation in continuously twisted, structurally chiral mediums (CTSCMs) has been analyzed in a recent paper [A. Lakhtakia, J. Acoust. Soc. Am. 95, 597–600 (1994)], and that analysis is extended here to piezoelectric CTSCMs (PCTSCMs). The stress tensor in a PCTSCM is symmetric, while the stiffness, the permittivity and the piezoelectric stress matrices vary helicoidally about the axis of spirality. Exact analytic solutions are reported for wave propagation along the axis of spirality in a PCTSCM. Because the eigenmodes are elliptically polarized with the vibration ellipse varying along the propagation direction, application of PCTSCMs for transducers with special polarizing properties is envisaged. The general analytical work reported is exemplified by application to a PCTSCM with a base Hex. 6 mm symmetry.