Exploiting Elastically Supported Masses in Cantilever for Resonance Frequencies Down-Shifted Vibration Energy Harvester

Hai Wang,Hongbo Qin,Wei Zhao,Bin Li,Min Zhang,Yan Liu

doi:10.3390/en12112207

Abstract

This paper presents a piezoelectric vibration energy harvester (PVEH) with resonance frequencies shifted down by elastically supported masses. The added elastic supporters can diminish the equivalent stiffness of the whole structure, leading to an evident decline in the resonance frequency of the cantilever body. Meantime, a new resonant peak is generated in the lower frequency range. The resonant frequency of the proposed PVEH can be easily adjusted by replacing the rubber band of the elastic support. The constructed configuration is theoretically investigated and experimentally verified. Compared with the conventional cantilever, the proposed device achieved a 46% decrease in resonance frequency and 87% enhancement in output power.

Highlights

Conventional piezoelectric vibration energy harvesters are usually constructed by a cantilever beam with a piezoelectric plate at the root and a mass at the free end [1,2,3]
The structural resonant frequency is often optimized as the key parameter to approach the frequency of target ambient vibrations, which is not very convenient for cantilever type piezoelectric vibration energy harvesters (PVEHs) [4]
Nonlinearity works well in broadening the device frequency band, which is often realized by structural nonlinearity [5,6] and magnetic coupling force [7]; frequency up-conversion transmits the energy of low-frequency vibrations to the piezoelectric beam and stimulate it to vibrate at its resonant point, and this phenomenon can be achieved by both contact [8] and contactless [9] ways; the multi-unit array approach uses several PVEH elements to adapt different target vibrations and can be regarded as a combination of several basic harvesters [10,11]

Summary

Introduction

Conventional piezoelectric vibration energy harvesters are usually constructed by a cantilever beam with a piezoelectric plate at the root and a mass at the free end [1,2,3]. 2. Theory and Design deformation of cantilever beam, the elastic range of rubber bands and the weight of proof masses, the Figure 1 illustrates a schematic of the proposed PVEH. Considering the10deformation cantilever beam, the elastic range of different rubber bands and thebut weight of proofsection masses, the number of of about 1.5 rubberofbands (3215, Deli, China) with lengths a similar diameter elastic supports setthe to two. 2. A longer rubber band processed a smaller and thenwas slightly lowered investigation on the effect of the of stiffness of elastic was conducted by changing investigation on the effect the stiffness ofsupporters elastick,supporters conducted by the thechanging valuesoutput ofthe k1 and k2 (k scheme) in Equation (2),Equation and the results shown corresponding voltage, which by the obtained trend in Table. Corresponding relationship between dimensionless voltage and the effective spring, dimensionless voltage k (N/m) dimensionless dimensionless voltagevoltage

Results and Discussion

Physical

Conclusions

V in the range