A Magnetic-Dependent Vibration Energy Harvester Based on the Tunable Point Defect in 2D Magneto-Elastic Phononic Crystals

Tian Deng,Shunzu Zhang,Yuanwen Gao

doi:10.3390/cryst9050261

Abstract

In this work, an innovative vibration energy harvester is designed by using the point defect effect of two-dimensional (2D) magneto-elastic phononic crystals (PCs) and the piezoelectric effect of piezoelectric material. A point defect is formed by removing the central Tenfenol-D rod to confine and enhance vibration energy into a spot, after which the vibration energy is electromechanically converted into electrical energy by attaching a piezoelectric patch into the area of the point defect. Numerical analysis of the point defect can be carried out by the finite element method in combination with the supercell technique. A 3D Zheng-Liu (Z-L) model which accurately describes the magneto-mechanical coupling constitutive behavior of magnetostrictive material is adopted to obtain variable band structures by applied magnetic field and pre-stress along the z direction. The piezoelectric material is utilized to predict the output voltage and power based on the capacity to convert vibration energy into electrical energy. For the proposed tunable vibration energy harvesting system, numerical results illuminate that band gaps (BGs) and defect bands of the in-plane mixed wave modes (XY modes) can be adjusted to a great extent by applied magnetic field and pre-stress, and thus a much larger range of vibration frequency and more broad-distributed energy can be obtained. The defect bands in the anti-plane wave mode (Z mode), however, have a slight change with applied magnetic field, which leads to a certain frequency range of energy harvesting. These results can provide guidance for the intelligent control of vibration insulation and the active design of continuous power supply for low power devices in engineering.

Highlights

With the ever-increasing development of self-powered wireless transmitters and embedded systems, the demands of independent power supply and extended lifespans become more and more intense [1,2]
The finite element method (FEM) is utilized to analyze and calculate the system of vibration energy harvesting based on magneto-elastic phononic crystals (PCs) with point defects
When increasing the compressive pre-stress to 20 MPa, by comparing Figure 6a,b, it can Figure 6a,b, it can be seen that the new defect bands of the first band gap (FBG) and new band gap (NBG) open in the higher magnetic be seen that the new defect bands of the FBG and NBG open in the higher magnetic field (1.1 kOe), field (1.1 kOe), and the edges and width of all these band gaps (BGs) and defect bands increase gradually and and the edges and width of all these BGs and defect bands increase gradually and reach a certain reach a certain constant at the saturated magnetic field. These results show that does constant at the saturated magnetic field. These results show that does the magnetic field have the magnetic field have a great effect on the BGs and defect bands, but that pre-stress has a a great effect on the BGs and defect bands, but that pre-stress has a significant effect on them

Summary

Introduction

With the ever-increasing development of self-powered wireless transmitters and embedded systems, the demands of independent power supply and extended lifespans become more and more intense [1,2]. The various forms of those resources include sunlight, waste heat, flowing water, wind, and mechanical vibration, etc. As a broad-distributed source, is the most prevalent within energy harvesting research [4], with numerous vibration energy generators of piezoelectric [6], electromagnetic [7], and electrostatic [8] conversion having been investigated. The piezoelectric generator, as one of the most effective collection devices, can harvest higher output. Crystals 2019, 9, 261 power owing to a better capability of electrical-mechanical coupling and higher strain for a given size. Considering the intrinsic advantage of high energy density in point defected phononic crystals (PCs), vibration energy can be accurately localized and enhanced at the point defect area, which can provide an excellent capability to achieve energy conversion through the direct piezoelectric effect

Objectives

Results

Conclusion