Electromechanical Coupling and Energy Conversion in a PZT-Coated Acoustic Black Hole Beam

The phenomenon of acoustic black hole (ABH) exhibits unique and appealing features when bending waves propagate along a structure with a tailored power-law thickness profile. The ABH-induced wave retarding and energy focussing are conducive to effective wave manipulation and energy harvesting. Using a PZT-coated ABH beam as a benchmark, this paper investigates the electromechanical coupling between the PZT patches and the host beam and explores the resultant energy conversion efficiency for potential energy-harvesting (EH) applications. An improved semi-analytical model, considering the full coupling among various electromechanical components in the system, is proposed based on Timoshenko deformation assumption and validated through comparisons with FEM and experimental results. Numerical analyses are then conducted to show typical ABH-specific features as well as the influence of the PZT layout on the electromechanical coupling of the system and the corresponding EH efficiency. Results show that ABH effects entail effective and broadband EH upon proper design of the system with due consideration of the PZT layout in relation to the wavelength and frequency range. Some design guidelines on the installation of PZTs are provided in view of maximization of the ABH benefits and the energy-harvesting performance.