Dr Liya Zhao is currently a Lecturer (Assistant Professor) in the School of Mechanical and Mechatronic Engineering at the University of Technology Sydney. She received her BEng in Civil Engineering from Tongji University in 2009, and her PhD in Structures and Mechanics from Nanyang Technological University Singapore in Dec 2015. After that, she worked as a Research Fellow at Nanyang Technological University Singapore. She joined the University of Technology Sydney as a Lecturer In Oct 2017. Her main research interests include energy harvesting, smart materials and structures, structural dynamics, vibration and wind energy, aeroelasticity, aero-electro-mechanical coupling, power electronics and piezoelectric devices. PUBLICATIONS: (citation 890, h-index 15, i10-index 19) Click Here
Shun Chen (Principal Supervisor, UTS)
Che Xu (Principal Supervisor, UTS)
Jie Gao (Co-supervisor, UTS)
Chaoyang Zhao (Co-supervisor, Nanyang Technological University Singapore)
Lead CI: “Generating Electricity during Sound Absorption: Novel Acoustic Metastructures for Simultaneous Structure-borne Noise Attenuation and Energy Harvesting”, Blue Sky Grant, UTS, Liya Zhao, Xiaojun Qiu, 2019, AUD 15,000
Seed grant: “Small-scale energy harvesting with smart materials and structures”, University of Technology Sydney, FEIT, Liya Zhao, 2018, AUD 20,000
CI: “Integrating online assessments for mechanical and mechatronic engineering”, University of Technology Sydney, FEIT MIDAS Teaching and Learning Grants, Paul Walker, Liya Zhao, Marc Carmichael and Enoch Zhao, 2018, AUD 5,000
Nanyang Engineering Doctoral Scholarship (NEDS) Award, Nanyang Technological University, Liya Zhao, 2011-2012, SGD 6,000
“Broadband energy harvesting optimized for shipboard intelligent wireless sensor and actuator networks”, Office of Naval Research Global, USA, Aug 2013 – Jul 2015, SGD 47,040. PI: Prof Yaowen Yang, Nanyang Technological University Singapore.
“Small scale energy harvesting” (M4081328), NTU Research Initiative, Aug 2013 – Jul 2016, SGD 180,000. PI: Prof Yaowen Yang, Nanyang Technological University Singapore.
Overseas Collaborator: “Wind-induced vibration energy harvesting using golf-like surface structure” National Natural Science Foundation of China (NSFC) 2020-2023. PI / Collaborator: A/Prof Junlei Wang, Zhengzhou University
Seminar: Small-scale wind and vibration energy harvesting for sustainable sensing. FEIT, University of Technology Sydney, 2018.
Invited talk: Renewable energy harvesting for sustainable monitoring applications. Laboratory of Composite Materials and Adaptive Structures, ETH Zurich, 2017
Invited talk: Renewable energy harvesting for sustainable monitoring applications. Newcastle University (Singapore Campus), 2017
Seminar: Small-Scale Wind Energy Harvesting Using Piezoelectric Materials, School of Civil and Environmental Engineering, Nanyang Technological University Singapore, 2015
Contributed talk: Analysis of power extraction circuits in galloping-based piezoelectric energy harvesters. Renewable Energy Exhibition, Singapore International Energy Week (RE@SIEW Expo), 2014.
Journal Editorial Board Member:
Conference Session Chair/Committee Member
- Session Chair - Energy Harvesting II: Piezo-based: SPIE Smart Structure + Nondestructive Evaluation, Active and Passive Smart Structures and Integrated Systems IX, California USA (converted to online conference) Apr 2020
- Organizing Committee Member: The 18th Asia Pacific Vibration Conference (APVC) 2019, Sydney, Australia, Nov 2019
- Session Chair: The 2nd International Conference on Modeling in Mechanics and Materials, Suzhou, China, March 2019
- Co-Chair and Co-Organizer: IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM) Session: Energy Harvesting for Self-Powered Health Monitoring, Auckland, New Zealand, July 2018
- Smart Materials and Structures (IOP)
- Applied Energy (Elsevier)
- Applied Physics Letter (AIP)
- Applied Mathematical Modeling (Elsevier)
- IEEE/ASME Transactions on Mechatronics (IEEE/ASME)
- Scientific Reports (Nature)
- Journal of Physics D: Applied Physics (IOP)
- Journal of Intelligent Material Systems and Structures (SAGE)
- Sensors and Actuators A: Physical (Elsevier)
- European Journal of Mechanics - B/Fluids (Elsevier)
- Communications in Nonlinear Science and Numerical Simulation (Elsevier)
- Journal of Energy Engineering (ASCE)
- Journal of Vibration and Acoustics (ASME)
- IET Renewable Power Generation (IEEE)
- Sensors (MDPI)
- Communications in Nonlinear Science and Numerical Simulation (Elsevier)
- Engineering Research Express (IOPscience)
- Advances in Mechanical Engineering (SAGE)
- International Journal of Non-Linear Mechanics (Elsevier)
Conference Paper Reviewer:
- ASME International Design Engineering Technical Conferences & Computers and Information in Engineering Conference (IDETC/CIE 2019)
- IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM 2018, 2019)
- 12th IEEE/ASME International Conference on Mechatronic and Embedded Systems and Applications (MESA 2016)
External Thesis Reviewer: 2019 Southern Cross University, Australia
Can supervise: YES
- Nonlinear adaptive structures for 1) small-scale wind energy harvesting with aeroelastic instabilities 2) broadband vibration energy harvesting
- Advanced power extraction interfaces for energy conversion enhancement
- Human motion energy harvesting; biosensing
- Wave energy harvesting
Smart Materials and Structures
- Adaptive devices for energy harvesting, vibration suppression, actuating and sensing
- Electromechanically coupled adaptive structures with smart materials (piezoelectric/flexoelectric/triboelectric/electret mechanisms)
Nonlinear Dynamics, Vibration Control
- Structural/material/geometric/aerodynamic nonlinearity
- Simultaneous energy harvesting and vibration suppression
Integrated Self-Powered Wireless Sensor Networks/Active Tags
- Sustainable physiological monitoring with self-powered body sensor networks
- Sustainable smart environmental/structural health monitoring
- Sustainable object tracking
I am recruiting PhD students. Students with Master's or Bachelor's Degree in Mechanical/Structural/Civil Engineering are welcome. Experiences in nonlinear dynamics, aerodynamics, finite element modeling, programming (e.g., Matlab) and experiments are highly desired. However, students with good academic records and strong self-motivation are all encouraged to apply.
Please refer to UTS website for general application requirement: https://www.uts.edu.au/research-and-teaching/research-degrees/applying-uts/how-apply
If interested, please send your CV and publications (if applicable) to me (email@example.com)
Hu, G, Wang, J, Qiao, H, Zhao, L, Li, Z & Tang, L 2020, 'An experimental study of a two‐degree‐of‐freedom galloping energy harvester', International Journal of Energy Research.View/Download from: Publisher's site
Tan, Q, Fan, K, Tao, K, Zhao, L & Cai, M 2020, 'A two-degree-of-freedom string-driven rotor for efficient energy harvesting from ultra-low frequency excitations', Energy, pp. 117107-117107.View/Download from: Publisher's site
Wang, J, Geng, L, Yang, K, Zhao, L, Wang, F & Yurchenko, D 2020, 'Dynamics of the double-beam piezo–magneto–elastic nonlinear wind energy harvester exhibiting galloping-based vibration', Nonlinear Dynamics.View/Download from: Publisher's site
Wang, J, Tang, L, Zhao, L, Hu, G, Song, R & Xu, K 2020, 'Equivalent circuit representation of a vortex‐induced vibration‐based energy harvester using a semi‐empirical lumped parameter approach', International Journal of Energy Research.View/Download from: Publisher's site
Small‐scale wind energy harvesting from vortex‐induced vibrations (VIV) has been introduced in recent years as a renewable power source for microelectronics and wireless sensors. Previous studies have focused on modeling and optimizing the VIV‐based piezoelectric energy harvester (VIVPEH) structures and simplified the complicated interface circuits as pure resistors with an alternating current (AC) output. In practice, an AC output is required to be transformed into a direct current (DC) followed by further regulations before being used for real applications. Incorporating the rectification and regulation, traditional theoretical and numerical models will become extremely cumbersome and even impossible. To address this issue, this work proposes an equivalent circuit model (ECM) for a typical VIVPEH. The Scanlan‐Ehsan aerodynamic force model is employed to describe the fluid‐structure interaction. Wind tunnel experiments are carried out to validate the derived model. The performances of the VIVPEH with AC and DC interface circuits are subsequently analyzed and compared to understand the influences of these circuits on the operational wind speed bandwidth, power output, vibration amplitude, and electrical damping.
Zhang, R, Zhao, L, Qiu, X, Zhang, H & Wang, X 2020, 'A comprehensive comparison of the vehicle vibration energy harvesting abilities of the regenerative shock absorbers predicted by the quarter, half and full vehicle suspension system models', Applied Energy, vol. 272, pp. 115180-115180.View/Download from: Publisher's site
Zhao, L 2020, 'Synchronization extension using a bistable galloping oscillator for enhanced power generation from concurrent wind and base vibration', APPLIED PHYSICS LETTERS, vol. 116, no. 5.View/Download from: Publisher's site
Wang, H, Zhao, L & Tang, L 2019, 'Effects of Electrical and Electromechanical Parameters on Performance of Galloping-Based Wind Energy Harvester with Piezoelectric and Electromagnetic Transductions', Vibration, vol. 2, no. 2, pp. 222-239.View/Download from: Publisher's site
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 damping 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.
Wang, J, Hu, G, Su, Z, Li, G, Zhao, W, Tang, L & Zhao, L 2019, 'A cross-coupled dual-beam for multi-directional energy harvesting from vortex induced vibrations', Smart Materials and Structures, vol. 28, no. 12.View/Download from: Publisher's site
This study proposes a cross-coupled dual-beam structure for energy harvesting from vortex-induced vibrations (VIV) induced by wind flows in different directions. A series of wind tunnel tests are conducted to investigate the performance of the proposed energy harvester subjected to the wind load with various speeds and directions. The upper and bottom piezoelectric beams can generate a maximum power output of 6.77 μW and 56.64 μW, respectively. The dominant operation frequencies in different directions are different which indicates a potential broadband capability. A parametric study is performed to reveal the effect of the dimension of the bluff body on the performance of the proposed energy harvester.
Wang, J, Tang, L, Zhao, L & Zhang, Z 2019, 'Efficiency investigation on energy harvesting from airflows in HVAC system based on galloping of isosceles triangle sectioned bluff bodies', Energy, vol. 172, pp. 1066-1078.View/Download from: Publisher's site
Galloping-based piezoelectric energy harvester (GPEH) has been used in power generation from small-scale airflows for low-power devices such as Micro-Electromechanical Systems (MEMS) and wireless sensing electronics. The bluff body plays an important role for the onset of galloping. Existing literature regarding analytical and numerical analysis of GPEH has focused on designs incorporating bluff bodies with a variety of cross-sections, such as square, D-section and regular triangle. In this work, a GPEH with triangular cross-section bluff bodies with different vertex angles is investigated. The aerodynamic characteristics are determined by Computational Fluid Dynamics (CFD) and verified by experimental data. Subsequently, an aero-electro-mechanical model with piezoelectric coupling is established and numerically solved. Furthermore, a parametric study is performed to investigate the influence of electromechanical coupling on the GPEH's behavior, with a focus on the threshold wind speed, transverse displacement and power output. It is determined that with weak coupling, the obtuse angle β = 130° is the most preferred vertex angle. This is the first documented determination that an obtuse angled isosceles triangle could be used for efficient galloping energy harvesting. The findings provide a guideline for designing efficient GPEHs with triangular bluff bodies.
Li, F, Yang, Y, Chi, Z, Zhao, L, Yang, Y & Luo, J 2018, 'Trinity: Enabling Self-Sustaining WSNs Indoors with Energy-Free Sensing and Networking', ACM Transactions on Embedded Computing Systems, vol. 17, no. 2.View/Download from: Publisher's site
Whereas a lot of efforts have been put on energy conservation in wireless sensor networks (WSNs), the limited lifetime of these systems still hampers their practical deployments. This situation is further exacerbated indoors, as conventional energy harvesting (e.g., solar) may not always work. To enable long-lived indoor sensing, we report in this article a self-sustaining sensing system that draws energy from indoor environments, adapts its duty-cycle to the harvested energy, and pays back the environment by enhancing the awareness of the indoor microclimate through an "energy-free" sensing. First of all, given the pervasive operation of heating, ventilation, and air conditioning (HVAC) systems indoors, our system harvests energy from airflow introduced by the HVAC systems to power each sensor node. Secondly, as the harvested power is tiny, an extremely low but synchronous duty-cycle has to be applied whereas the system gets no energy surplus to support existing synchronization schemes. So, we design two complementary synchronization schemes that cost virtually no energy. Finally, we exploit the feature of our harvester to sense the airflow speed in an energy-free manner. To our knowledge, this is the first indoor wireless sensing system that encapsulates energy harvesting, network operating, and sensing all together.
Zhao, L & Yang, Y 2018, 'An impact-based broadband aeroelastic energy harvester for concurrent wind and base vibration energy harvesting', Applied Energy, vol. 212, pp. 233-243.View/Download from: Publisher's site
© 2017 This paper proposes a novel broadband energy harvester to concurrently harvest energy from base vibrations and wind flows by utilizing a mechanical stopper. A problem for a conventional wind energy harvester is that it can only effectively harness energy from two types of excitations around its resonance frequency. The proposed design consists of a D-shape-sectioned bluff body attached to a piezoelectric cantilever, and a mechanical stopper fixed at the bottom of the cantilever which introduces piecewise linearity through its impact with the bluff body. The quasi-periodic oscillations are converted to periodic vibration due to the introduction of the mechanical stopper, which forces the two excitation frequencies to lock into each other. Broadened bandwidth for effective concurrent energy harvesting is thus achieved, and at the same time, the beam deflection is slightly mitigated and fully utilized for power conversion. The experiment shows that with the stopper-bluff body distance of 19.5 mm, the output power from the proposed harvesting device increases steadily from 3.0 mW at 17.3 Hz to 3.8 mW at 19.1 Hz at a wind speed of 5.5 m/s and a base acceleration of 0.5 g. A guideline for the stopper configuration is also provided for performance enhancement of the broadband concurrent wind and vibration energy harvester.
The interdisciplinary research area of small scale energy harvesting has attracted tremendous interests in the past decades, with a goal of ultimately realizing self-powered electronic systems. Among the various available ambient energy sources which can be converted into electricity, wind energy is a most promising and ubiquitous source in both outdoor and indoor environments. Significant research outcomes have been produced on small scale wind energy harvesting in the literature, mostly based on piezoelectric conversion. Especially, modeling methods of wind energy harvesting techniques plays a greatly important role in accurate performance evaluations as well as efficient parameter optimizations. The purpose of this paper is to present a guideline on the modeling methods of small-scale wind energy harvesters. The mechanisms and characteristics of different types of aeroelastic instabilities are presented first, including the vortex-induced vibration, galloping, flutter, wake galloping and turbulence-induced vibration. Next, the modeling methods are reviewed in detail, which are classified into three categories: the mathematical modeling method, the equivalent circuit modeling method, and the computational fluid dynamics (CFD) method. This paper aims to provide useful guidance to researchers from various disciplines when they want to develop and model a multi-way coupled wind piezoelectric energy harvester.
Zhao, L & Yang, Y 2017, 'Toward Small-Scale Wind Energy Harvesting: Design, Enhancement, Performance Comparison, and Applicability', Shock and Vibration, vol. 2017, pp. 1-31.View/Download from: Publisher's site
The concept of harvesting ambient energy as an alternative power supply for electronic systems like remote sensors to avoid replacement of depleted batteries has been enthusiastically investigated over the past few years. Wind energy is a potential power source which is ubiquitous in both indoor and outdoor environments. The increasing research interests have resulted in numerous techniques on small-scale wind energy harvesting, and a rigorous and quantitative comparison is necessary to provide the academic community a guideline. This paper reviews the recent advances on various wind power harvesting techniques ranging between cm-scaled wind turbines and windmills, harvesters based on aeroelasticities, and those based on turbulence and other types of working principles, mainly from a quantitative perspective. The merits, weaknesses, and applicability of different prototypes are discussed in detail. Also, efficiency enhancing methods are summarized from two aspects, that is, structural modification aspect and interface circuit improvement aspect. Studies on integrating wind energy harvesters with wireless sensors for potential practical uses are also reviewed. The purpose of this paper is to provide useful guidance to researchers from various disciplines interested in small-scale wind energy harvesting and help them build a quantitative understanding of this technique.
Zhao, L, Tang, L, Liang, J & Yang, Y 2017, 'Synergy of Wind Energy Harvesting and Synchronized Switch Harvesting Interface Circuit', IEEE/ASME Transactions on Mechatronics, vol. 22, no. 2, pp. 1093-1103.View/Download from: Publisher's site
Due to the complex aero-electro-mechanical coupling involved in wind energy harvesting systems, power enhancing efforts in the literature are mostly devoted to structural modifications while the interface circuit is simplified to a resistive ac load. Yet the ac outputs are not applicable for practical usage. In this paper, we study the dynamics and dc power generation of galloping energy harvester. In particular, the enhancement of wind power extraction using the synchronized switching harvesting on inductor (SSHI) power conditioning circuit is emphasized. Analytical solution of the steady-state mechanical and electrical responses with the SSHI interface is derived explicitly and validated with wind tunnel experiment and circuit simulation. The performance of SSHI interface is compared to that of a standard bridge rectifier interface circuit. It shows that the SSHI interface achieves tremendous power enhancement in a weak-coupling system, and higher wind speeds render more significant power enhancement. Moreover, given the same wind condition and output power requirement, a system connected to the SSHI uses much less piezoelectric material compared to that connected to the standard circuit. With a weak-coupling harvester operating at a wind speed of 7 m/s, the SSHI can harvest up to 143% more wind power than the standard circuit.
Zhao, L, Tang, L & Yang, Y 2016, 'Synchronized charge extraction in galloping piezoelectric energy harvesting', Journal of Intelligent Material Systems and Structures, vol. 27, no. 4, pp. 453-468.View/Download from: Publisher's site
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 amplitude 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.
Tang, L, Zhao, L, Yang, Y & Lefeuvre, E 2015, 'Equivalent Circuit Representation and Analysis of Galloping-Based Wind Energy Harvesting', IEEE/ASME Transactions on Mechatronics, vol. 20, no. 2, pp. 834-844.View/Download from: Publisher's site
Small-scale wind energy can be harvested for wireless sensing applications by exploiting the galloping phenomenon of a bluff body attached to a piezoelectric cantilever. Certain predictive model is required to understand the behavior of such a galloping-based piezoelectric energy harvester (GPEH). Conventional analytical and numerical models have simplified the interface circuit as a pure resistor. In practice, the energy generated by the harvester should be rectified before delivery to a real application. In such a case, the formulation of analytical or numerical model becomes cumbersome considering the complex coupling between the structure, fluid, piezoelectric transducer, and practical interface circuit. This paper proposes an equivalent circuit representation approach to predict the performance of GPEHs, capable of incorporating various interface circuits. The mechanical parameters and piezoelectric coupling in the system are represented by standard electronic components and the aerodynamic force by a user-defined component (nonstandard). The entire system is modeled in a circuit simulator for system-level simulation and evaluation. The proposed approach is verified by theoretical solution and experiment. Subsequent parametric study is performed to investigate the influence of standard ac and dc interfaces on the GPEH's behavior, with a focus on the threshold of galloping, power output, and induced electrical damping.
Zhao, L & Yang, Y 2015, 'Analytical solutions for galloping-based piezoelectric energy harvesters with various interfacing circuits', Smart Materials and Structures, vol. 24, no. 7, pp. 075023-075023.View/Download from: Publisher's site
Recently, the concept of harvesting available energy from the surrounding environment of electronic devices to implement self-powered stand-alone units has attracted a dramatic increase in interest. Many studies have been conducted on the analytical solutions of output responses for vibration-based piezoelectric energy harvesters (VPEHs), with both simple ac circuit and advanced circuits such as impedance adaptation, synchronized switching harvesting on inductor (SSHI) and synchronized charge extraction (SCE). However, very little effort has been devoted to deriving explicit output responses of aeroelastic piezoelectric energy harvesters, especially for cases involving sophisticated interface circuits. This paper proposes analytical solutions of the responses of a galloping-based piezoelectric energy harvester (GPEH). Three different interfacing circuits, including the simple ac, standard and SCE circuits, are considered in the analysis, with which the explicit expressions of power, voltage and displacement amplitude are derived. The optimal load and coupling are calculated for maximum power generation. The cut-in wind speeds for these circuits are also formulated. Wind tunnel experiments based on a prototype of a GPEH with a square sectioned bluff body and circuit simulation based on the equivalent circuit model are carried out to validate the analysis. Recommendations on the applicability of different circuits are provided based on the observed behaviors of the circuits. The proposed theoretical solutions provide significant guidelines for accurate evaluation of effectiveness of GPEHs and the scheme of normalization makes it convenient to compare devices with various parameters.
In this article, we propose an easy but quite effective method to significantly enhance the power generation capability of an aeroelastic energy harvester. The method is to attach a beam stiffener to the substrate of the harvester, which works as an electromechanical coupling magnifier. It is shown to be effective for all three considered types of harvesters based on galloping, vortex-induced vibration and flutter, leading to a superior performance over the conventional designs without the beam stiffener, with dozens of times the increase in power and an almost 100% increase in the power extraction efficiency yet with comparable or even smaller transverse displacement. Choice guidelines of optimal types of energy harvesters are also suggested based on the given wind situations where the electronic device is located.
Zhao, L, Tang, L & Yang, Y 2014, 'Enhanced piezoelectric galloping energy harvesting using 2 degree-of-freedom cut-out cantilever with magnetic interaction', Japanese Journal of Applied Physics, vol. 53, no. 6, pp. 060302-060302.View/Download from: Publisher's site
Most piezoelectric aeroelastic energy harvesters operate effectively only at high wind speeds or within a narrow speed range. To overcome this issue, we propose a 2 degree-of-freedom (2DOF) piezoelectric aeroelastic energy harvester with a cut-out cantilever and two magnets. Translational galloping is induced with a square cross-sectioned bluff body attached at the cantilever tip. Magnetic interaction is introduced to create stiffness nonlinearity. The proposed device is demonstrated by wind tunnel tests to have a lower cut-in wind speed of 1 m/s and higher power output than the conventional 1 degree-of-freedom (1DOF) harvester in the low wind speed range up to 4.5 m/s.
Yang, Y, Zhao, L & Tang, L 2013, 'Comparative study of tip cross-sections for efficient galloping energy harvesting', Applied Physics Letters, vol. 102, no. 6, pp. 064105-064105.View/Download from: Publisher's site
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.
Zhao, L, Tang, L & Yang, Y 2013, 'Comparison of modeling methods and parametric study for a piezoelectric wind energy harvester', Smart Materials and Structures, vol. 22, no. 12, pp. 125003-125003.View/Download from: Publisher's site
Harvesting flow energy by exploiting transverse galloping of a bluff body attached to a piezoelectric cantilever is a prospective method to power wireless sensing systems. In order to better understand the electroaeroelastic behavior and further improve the galloping piezoelectric energy harvester (GPEH), an effective analytical model is required, which needs to incorporate both the electromechanical coupling and the aerodynamic force. Available electromechanical models for the GPEH include the lumped parameter single-degree-of-freedom (SDOF) model, the approximated distributed parameter model based on Rayleigh–Ritz discretization, and the distributed parameter model with Euler–Bernoulli beam representation. Each modeling method has its own advantages. The corresponding aerodynamic models are formulated using quasi-steady hypothesis (QSH). In this paper, the SDOF model, the Euler–Bernoulli distributed parameter model using single mode and the Euler–Bernoulli distributed parameter model using multi-modes are compared and validated with experimental results. Based on the comparison and validation, the most effective model is employed for the subsequent parametric study. The effects of load resistance, wind exposure area of the bluff body, mass of the bluff body and length of the piezoelectric sheets on the power output are investigated. These simulations can be exploited for designing and optimizing GPEHs for better performance.
Zhao, L 2020, 'A bistable galloping energy harvester for enhanced concurrent wind and base vibration energy harvesting', Active and Passive Smart Structures and Integrated Systems IX, Active and Passive Smart Structures and Integrated Systems IX, SPIE, California.View/Download from: Publisher's site
Zhao, L 2019, 'Analytical solutions for a broadband concurrent aeroelastic and base vibratory energy harvester', Proceedings of SPIE - The International Society for Optical Engineering, Active and Passive Smart Structures and Integrated Systems XIII, SPIE, Denver, Colorado, United States.View/Download from: Publisher's site
© 2019 Copyright SPIE. Concurrent energy harvesting by simultaneously harvesting wind and base vibration energy has received very little attention until recently. Yet a major problem with a traditional wind energy harvester under concurrent loadings is the dramatically reduced efficiency when the base vibration frequency deviates from the resonance. This paper investigates a novel design to enhance concurrent energy harvesting from concurrent base vibrations and wind flows. A piecewiselinear aeroelastic energy harvester is integrated with a stopper which can also work as a complementary generator. In order to fast and accurately characterize the response of the harvester, exact analytical solutions are derived based on the harmonic balance analysis and method of averaging. The interaction of the two coexisting excitation frequencies as well as the impact effects between the aeroelastic energy harvester and the stopper are fully considered. Closed-form expressions for both mechanical and electrical responses are presented and validated numerically. Results show that a greatly widened bandwidth is achieved with the proposed design where both aeroelastic and base vibratory energy are effectively harnessed. The analytical solutions are essential to fully understand the characteristics of this new kind of broadband concurrent energy harvester, and serve as a guideline for efficient performance evaluation and parameter optimization.
Zhao, L 2019, 'Concurrent wind and base vibration energy harvesting with a broadband bistable aeroelastic energy harvester', IOP Conference Series: Materials Science and Engineering, Modeling in Mechanics and Materials, IOP Publishing, Suzhou, pp. 012081-012081.View/Download from: Publisher's site
Zhao, L 2018, 'Performance Enhancement of an Aeroelastic Energy Harvester for Efficient Power Harvesting from Concurrent Wind Flows and Base Vibrations', 2018 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM), International Conference on Advanced Intelligent Mechatronics, IEEE, Auckland, New Zealand, pp. 780-785.View/Download from: Publisher's site
In this paper, using a high frequency mechanical stopper as a complementary energy harvester is proposed to improve the performance of energy harvesting from concurrent wind flows and base vibrations. Galloping aeroelasticity of a square-sectioned bluff body is employed to achieve limit-cycle structural oscillations. The analysis demonstrates that the bandwidth for effectively harnessing both aerodynamic and base vibratory energy is substantially widened, and simultaneously, the total power amplitude is significantly enhanced as compared to the original linear galloping energy harvester. It is concluded that the proposed system is viable solution to enhance energy conversion in situations where wind flows and base vibrations are coexisting.
Zhao, L & Yang, Y 2017, 'Modeling and experiment of a broadband piecewise linear energy harvester for concurrent base vibration and wind energy harvesting', SS1306_3780, The 2017 World Congress on Advances in Structural Engineering and Mechanics.
Zhao, L, Liang, J, Tang, L, Yang, Y & Liu, H 2015, 'Enhancement of Galloping-based Wind Energy Harvesting by Synchronized Switching Interface Circuits', 94310E, SPIE Smart Structures and Materials+ Nondestructive Evaluation and Health Monitoring, United States.View/Download from: Publisher's site
Avvari, PV, Yang, Y, Soh, CK & Zhao, L 2014, 'Bandwidth enhancement of a piezoelectric energy harvester using parametrically induced vibrations', paper ID012, 25nd International Conference on Adaptive Structures and Technologies (ICAST 2014), The Netherlands.
Zhao, L, Chong, J, Ng, TLJ & Yang, Y 2014, 'Enhancement of Aeroelastic Energy Harvesting from Galloping, Vortex-induced Vibrations and Flutter with a Beam Stiffener', paper ID009, 25nd International Conference on Adaptive Structures and Technologies (ICAST 2014).
Zhao, L, Tang, L, Wu, H & Yang, Y 2014, 'Synchronized charge extraction for aeroelastic energy harvesting', 90570N, SPIE Smart Structures and Materials+ Nondestructive Evaluation and Health Monitoring,.View/Download from: Publisher's site
Xiang, T, Chi, Z, Li, F, Luo, J, Tang, L, Zhao, L & Yang, Y 2013, 'Powering indoor sensing with airflows: a trinity of energy harvesting, synchronous duty-cycling, and sensing', 73, 11th ACM Conference on Embedded Networked Sensor Systems, Italy.View/Download from: Publisher's site
Xiang, T, Chi, Z, Li, F, Luo, J, Tang, L, Zhao, L & Yang, Y 2013, 'Powering indoor sensing with airflows: A trinity of energy harvesting, synchronous duty-cycling, and sensing', SenSys 2013 - Proceedings of the 11th ACM Conference on Embedded Networked Sensor Systems.View/Download from: Publisher's site
Whereas a lot of efforts have been put on energy conservation in wireless sensor networks, the limited lifetime of these systems still hampers their practical deployments. This situation is further exacerbated indoors, as conventional energy harvesting (e.g., solar) ceases to work. To enable longlived indoor sensing, we report in this paper a self-sustaining sensing system that draws energy from indoor environments, adapts its duty-cycle to the harvested energy, and pays back the environment by enhancing the awareness of the indoor microclimate through an \energy-free" sensing. First of all, given the pervasive operation of heating, ven- tilation and air conditioning (HVAC) systems indoors, our system harvests energy from air ow introduced by the HVAC systems to power each sensor node. Secondly, as the harvested power is tiny (only of hundreds of W), an extremely low but synchronous duty-cycle has to be applied whereas the system gets no energy surplus to support existing synchronization schemes. So we d sign two complementary synchronization schemes that cost virtually no energy. Finally, we exploit the feature of our harvester to sense the air ow speed (which can be used to infer the indoor microclimate) in an energy-free manner. To our knowledge, this is the first indoor wireless sensing system that encapsulates energy harvesting, network operating, and sensing all together.
Tang, L, Yang, Y & Zhao, L 2012, 'Magnetic Coupled Cantilever Piezoelectric Energy Harvester', 811-818, ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, United States.View/Download from: Publisher's site
Wang, J, Zhao, L & Tang, L 2018, 'A Galloping Based Piezoelectric Energy Harvester'.
Li, F, Xiang, T, Chi, Z, Luo, J, Tang, L, Zhao, L & Yang, Y, 'Demo Abstract: Powering Indoor Sensing with Airflows–A Trinity of Energy Harvesting, Synchronous Duty-Cycling, and Sensing'.
Zhao, L, 'Small-scale Wind Energy Harvesting Using Piezoelectric Materials'.
Nanyang Technological University Singapore
The University of Auckland