Active broadband sound transmission loss control through an arbitrary thick smart Piezo-laminated cylinder

Abstract

The feedback control strategy is utilized for the enhancement of the sound transmission loss (STL) through an infinite thick hollow Piezo-laminated cylinder of arbitrary thickness insonified by an oblique progressive incident plane wave. The close form formulation is accomplished by utilizing the sound wave equation, the three-dimensional (3D) exact theory of elasticity and piezoelasticity. The active control strategy is achieved by sending a control signal from the distributed piezoelectric sensor layer through a controller with certain feedback gain to drive the external piezoelectric actuators. The mechanical stress generated by the piezo-actuator layer cancels the parts of the input incident wave to enhance the STL. Comprehensive numerical studies are carried out to investigate the poling direction and feedback gain effects on the STL. The results show that in the case of radially polarized piezoelectric materials, the feedback control provides significant sound enhancement especially, when the angle of the incident wave is close to normal, however, in the case of axially polarized piezoelectric materials, the control feedback strategy reduces the unfavorable oscillatory motion of the cylinder in addition to providing a superior sound isolation enhancement, particularly for near-grazing incident angles. The accuracy of the proposed solution is confirmed by comparing the presented results with the ones from the simplified models in the literature as well as the commercial finite element package Comsol Multiphysics.