ORCID Profile
0000-0001-9031-4190
Current Organisation
The University of Auckland
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Publisher: IOP Publishing
Date: 12-05-2014
Publisher: SPIE
Date: 09-03-2014
DOI: 10.1117/12.2044993
Publisher: AIP Publishing
Date: 06-09-2021
DOI: 10.1063/5.0063488
Publisher: SAGE Publications
Date: 27-06-2018
Abstract: In this article, a soft magneto-sensitive elastomer cantilever with strong nonlinear behaviour is presented. With the help of a permanent magnet, a strong nonlinear behaviour is observed under low-frequency and low-magnitude excitation, which demonstrated its potential for vibrational energy harvesting. A theoretical model is developed which incorporates the nonlinear magnetic interaction in an Euler–Bernoulli beam. The theoretical model is further discretized using finite element method, and the frequency response was obtained through numerical simulation. Frequency sweep experiment was conducted to validate the model and investigate the nonlinear behaviour of the cantilever under different excitations. With the validated model, various contributing factors were parametrically studied to investigate their influences towards the dynamic behaviour of the cantilever. The results show that magnetic force dominates the linear stiffness increase of soft magneto-sensitive elastomer cantilever rather than the magnetorheological effect, and the nonlinear performance of soft magneto-sensitive elastomer cantilever mainly derives from horizontal magnetic force variations during vibration. These properties make the soft magneto-sensitive elastomer cantilever an attractive candidate to automatically tune and broaden the operational bandwidth of vibrational energy harvesters.
Publisher: Elsevier BV
Date: 04-2019
Publisher: AIP Publishing
Date: 11-02-2013
DOI: 10.1063/1.4792737
Abstract: This letter presents a comparative study of different tip cross-sections for small scale wind energy harvesting based on galloping phenomenon. A prototype device is fabricated with a piezoelectric cantilever and a tip body with various cross-section profiles (square, rectangle, triangle, and D-shape) and tested in a wind tunnel. Experimental results demonstrate the superiority of the square-sectioned tip for the low cut-in wind speed of 2.5 m/s and the high peak power of 8.4 mW. An analytical model is established and verified by the experimental results. It is recommended that the square section should be used for small wind galloping energy harvesters.
Publisher: IOP Publishing
Date: 14-12-2018
Publisher: ACM
Date: 11-11-2013
Publisher: IOP Publishing
Date: 11-2013
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2015
Publisher: IOP Publishing
Date: 15-11-2019
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2017
Publisher: Elsevier BV
Date: 03-2019
Publisher: SAGE Publications
Date: 12-01-2022
DOI: 10.1177/1045389X211072520
Abstract: This paper presents a study of a two-degree-of-freedom (2DOF) piezoelectric energy harvester (PEH) under concurrent aeroelastic and base excitation. The governing equations of the theoretical model under the combined excitation are developed and solved analytically using the harmonic balance method. Based on the electro-mechanical analogies, an equivalent circuit model is established. The energy harvesting performance of the 2DOF PEH under different wind speeds but the same base excitation is investigated. Voltage litudes of various response components with different frequencies are predicted by the analytical method and verified by the circuit simulation. The root-mean-square (RMS) voltage is used to measure the actual performance of the 2DOF PEH. Around the resonance state, the 2DOF PEH has been found to produce a larger voltage output than the conventional SDOF PEH. Moreover, several interesting phenomena, such as the quasi-periodic oscillation and the peak-to-valley transition, have been observed in the circuit simulation and explained by the analytical solution. The developed methodology in this paper can be easily adapted to analyze other similar types of multiple-degree-of-freedom (MDOF) PEHs under concurrent aeroelastic and base excitation.
Publisher: SAGE Publications
Date: 19-02-2015
Abstract: Energy harvesting from aeroelastic instabilities has attracted numerous interests with the purpose of implementing self-powered wireless sensing networks. Meanwhile, considerable efforts have been devoted to optimizing the interface circuit to boost the power output from vibration-based piezoelectric energy harvester, such as impedance matching, synchronized charge extraction, and synchronized switching harvesting on inductor. However, application of these circuits in aeroelastic energy harvesting has received far less attentions. With an experimentally validated equivalent circuit model, this article investigates the feasibility of employing the synchronized charge extraction interface for a galloping-based piezoelectric energy harvester. The performance of synchronized charge extraction circuit is compared with a standard circuit, revealing three main advantages of synchronized charge extraction in galloping-based piezoelectric energy harvester system: first, the output power from synchronized charge extraction is independent of electrical load, eliminating the requirement of impedance matching and thus ensuring the flexibility of adjusting the galloping-based piezoelectric energy harvester system for practical applications second, the synchronized charge extraction circuit helps to save piezoelectric materials by 75% compared to the standard circuit and third, the displacement litude of galloping-based piezoelectric energy harvesters with synchronized charge extraction is much smaller, alleviating the fatigue problem and enhancing the durability of the harvesting system. Finally, a theoretical criterion is proposed to determine the applicable region of synchronized charge extraction in galloping-based piezoelectric energy harvester.
Publisher: ACM
Date: 11-11-2013
Publisher: American Society of Mechanical Engineers
Date: 19-09-2012
Abstract: A galloping piezoelectric harvester for small wind energy harvesting usually consists of a cantilever beam cl ed at one end and a tip body attached to its free end. The tip body has significant influence on the aeroelastic characteristic of the harvester thus the efficiency of energy harvesting. However, no systematic study on the tip body is available in the literature. This article focuses on the effect of tip body on the performance of the harvester. A prototype device is fabricated with different tip bodies having various cross sections, lengths, and masses. Wind tunnel tests are conducted to determine the influence of these parameters on the power generated. A peak output power of 8.4 mW is achieved at a wind velocity of 8 m/s for the harvester with a tip of square section. An analytical model integrating electromechanical and aerodynamic formulations is established, and the results agree well with the experiments. It is recommended that the tip of square section should be used for galloping energy harvesters.
Publisher: SPIE
Date: 02-04-2015
DOI: 10.1117/12.2084000
Publisher: Elsevier BV
Date: 04-2018
Publisher: Hindawi Limited
Date: 05-2020
DOI: 10.1002/ER.5228
Publisher: American Society of Mechanical Engineers
Date: 19-09-2012
Abstract: A conventional vibration energy harvester is usually designed as a linear single-degree-of-freedom (1DOF) resonator. The efforts to improve its efficiency involve two aspects, i.e., enlarging the magnitude of output and widening the operating bandwidth. In this paper, we propose a magnetic coupled cantilever piezoelectric energy harvester (PEH) to achieve the above two goals. Different from other reported magnetic coupled PEHs, the magnetic interaction in the proposed design is introduced by a magnetic oscillator. Firstly, the lumped parameter models are established for the conventional linear PEH, the nonlinear PEH with a fixed magnet and the proposed PEH with a magnetic oscillator. The governing equations of the three systems are then provided in the state space form and their dynamics can be simulated by numerical integration. Subsequently, experimental tests are performed to validate the models. Both experiment and simulation show that the dynamics of the magnetic oscillator is able to not only broaden the operating bandwidth but also enhance the maximum power output of the PEH. Based on the validated model, parametric study is conducted to optimize the system performance.
Publisher: Elsevier BV
Date: 12-2018
Publisher: Hindawi Limited
Date: 09-2020
DOI: 10.1002/ER.5878
Publisher: MDPI AG
Date: 20-06-2019
Abstract: This paper presents an analysis of galloping-based wind energy harvesters with piezoelectric and electromagnetic transductions. The lumped parameter models of the galloping-based piezoelectric energy harvester (GPEH) and galloping-based electromagnetic energy harvester (GEMEH) are developed and the approximate analytical solutions of the equations are derived using the harmonic balance method (HBM). The accuracy of the approximate analytical solutions is validated by the numerical solutions. A parametric study is then conducted based on the validated models and solutions to understand the effects of the dimensionless load resistance, r, and electromechanical coupling strength (EMCS) on various quantities indicating the performance of the harvesters, including the dimensionless oscillating frequency, cut-in wind speed, displacement, and average power output. The results show that both r and EMCS can affect the dimensionless oscillating frequencies of the GPEH and GEMEH in a narrow frequency range around the natural frequency. A significant decrease in the displacement around r = 1 for GEPH and at a low r for GEMEH indicates the d ing effect induced by the increase in EMCS. There are two optimal r to achieve the maximal power output for GPEH given strong EMCS while there is only one optimal r for GEMEH. Both GPEH and GEMEH show similar characteristics in that the optimal power outputs can reach saturation with an increase of the EMCS. The findings from the parametric study provide useful guidelines for the design of galloping-based energy harvesters with different energy conversion mechanisms.
No related grants have been discovered for Lihua Tang.