Research On Broadband Piezoelectrical Vibration Energy Harvesting Using Acoustic Black Hole Effect

The ABH effect allows for a smooth reduction of the phase velocity of elastic waves,minimizing the reflected wave energy,creating high energy density areas in the host structure,which shows great potential in vibration-based energy harvesting.Among existing models analyzing the harvesting performance using the ABH effect,the wavelength compression which may decrease the harvesting efficiency hasn't been considered.The structural design can not meet the requirements in practical engineering applications.Meanwhile,the investigation of the full coupling between the ABH effect and piezoelectric patches is necessary to guide the design of the harvesting system.To tackle these problems,fully coupled finite element models of ABH tapered structures with surface mounted piezoelectric patches were developed to evaluate the harvesting performance of the system.The numerical results were further compared with experimental measurements to confirm the harvesting performance.The work done in this paper mainly includes,Firstly,the wavelength compression was considered to help design the harvesting system appropriately,which drastically increases the harvested power.Fully numerical models of the harvesting system were developed to analyze the flexural wave propagation in ABH structures and harvesting performance to both steady state and transient excitations.Experiments were conducted to verify the harvesting performance of the proposed system.In addition,the full coupling between the ABH features and piezoelectric transducers were investigated.A detailed analysis on the mass,stiffness and piezoelectric constants was carried out to research the influence on the energy concentration effect.Electrical circuits were connected to transducers for harvesting converted energy and the damping effect was evaluated.Finally,a configuration with embedded ABH features suitable for practical engineering applications was proposed.Whilst ensuring an effective ABH effect,the ABH frame can provide much better static properties in terms of structural stiffness and strength.A simplified model of an engineering application was developed to analyze the full coupling between the add-on device and the primary structure.