Imperial College London

ProfessorHailingFu

Faculty of EngineeringDepartment of Aeronautics

Visiting Researcher
 
 
 
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420City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

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42 results found

Zhao L, Lu ZQ, Zhang FY, Fu HL, Ding H, Chen LQet al., 2024, Rotational nonlinear energy harvesting via an orthogonal dual-beam, Mechanical Systems and Signal Processing, Vol: 211, ISSN: 0888-3270

Various nonlinear energy harvesters that harvest energy from rotational motion have been investigated, but their performance at low frequencies is always deficiency. To realize the efficient harvesting of low frequency rotational motion energy, rotational nonlinear energy harvesting via an orthogonally arranged dual-beam is proposed for the first time. Based on the energy method, the electromechanical coupling equation of orthogonally arranged dual-beam in rotating motion is derived in detail. The harmonic balance method together with arc length continuation is employed to approximate the frequency response functions of the output power. To deeply explore the nonlinear dynamic behavior of the system, numerical analysis is conducted to obtain the output voltage and phase diagram in the time domain. Finally, the theoretical analysis results are verified through experiments. The results demonstrate that the vertical arrangement of nonlinear dual-beam in rotational motion effectively improved the energy harvesting efficiency at low frequencies, with excellent energy harvesting performance. This study provides an effective technical approach to energy harvesting for low frequency rotating systems.

Journal article

Wang X, Lu Y, Jiang J, Lv C, Fu H, Xie Met al., 2024, A Flexible Piezoelectric PVDF/MXene Pressure Sensor for Roughness Discrimination, IEEE Sensors Journal, Vol: 24, Pages: 7176-7184, ISSN: 1530-437X

The accurate assessment of surface roughness is critical for numerous applications ranging from quality control in manufacturing to material characterization. To achieve a functional capability of roughness perception, a flexible pressure sensor based on polyvinylidene fluoride-Ti3C2 (PVDF/MXene) nanocomposite is developed. The sensor consists of electrospun PVDF nanofibers embedded with 2-D MXene nanosheets. The MXene enhances the piezoelectric \beta -phase content of the PVDF up to 97.2% at optimal loading of 2.5 wt%. The PVDF/MXene nanocomposite exhibited high piezoelectric voltage sensitivity up to 0.059 V kPa^{-{1}} under applied pressures. The wavelet transform analysis of signals obtained by scanning the sensor on sandpapers of varying roughness showed distinct time-frequency patterns corresponding to different surface roughness levels. Unsupervised dimensionality reduction using t-distributed stochastic neighbor embedding (t-SNE) revealed clustering of roughness data into distinct categories. A convolutional neural network (CNN) classifier achieved 98% accuracy in categorizing the surface roughness based on the sensor signal wavelet transforms. The piezoelectric nanocomposite sensor shows promise for surface metrology applications.

Journal article

Zheng X, He L, Yu G, Wang H, Fu H, Huang Het al., 2023, Sequentially-excited multi-oscillator piezoelectric rotary energy harvester for charging capacity enhancement, Sustainable Energy Technologies and Assessments, Vol: 60, ISSN: 2213-1388

Energy harvesting technology can provide a power solution for IoT sensors. In this paper, a sequentially-excited multi-oscillator piezoelectric rotary energy harvester (SEMPREH) is proposed. A theoretical model of the piezoelectric oscillator was established, and a magnetic simulation analysis was performed. The results show that for the same exciting magnet arrangement (A) and rotation speed, the voltages when the exciting and excited magnets in attraction are higher than in repulsion. The waveforms are denser and have a higher charging capacity with A4 compared to A1 (simultaneous excitation). The optimum combination is attraction and A4 with a maximum peak-to-peak open-circuit voltage of 23.2 V at 200 RPM, and the maximum average power at the same speed is 1.11 mW (at 30 kΩ). The SEMPREH assembled with the wind turbine can light up the LED board at 4.13 m/s. It has the potential to power microelectromechanical systems such as IoT sensors.

Journal article

Lu Z-Q, Chen J, Fu H-L, Ding H, Chen L-Qet al., 2023, Nonlinear energy harvesting via an axially moving piezoelectric beam with both <i>d</i> <sub>31</sub> and <i>d</i> <sub>33</sub> modes, JOURNAL OF PHYSICS D-APPLIED PHYSICS, Vol: 56, ISSN: 0022-3727

Journal article

Liu M, Zhang Y, Fu H, Qin Y, Ding A, Yeatman EMet al., 2023, A seesaw-inspired bistable energy harvester with adjustable potential wells for self-powered internet of train monitoring, APPLIED ENERGY, Vol: 337, ISSN: 0306-2619

Journal article

Fu H, Jiang J, Hu S, Rao J, Theodossiades Set al., 2023, A multi-stable ultra-low frequency energy harvester using a nonlinear pendulum and piezoelectric transduction for self-powered sensing, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, Vol: 189, ISSN: 0888-3270

Journal article

Masabi SN, Fu H, Theodossiades S, 2022, A bistable rotary-translational energy harvester from ultra-low-frequency motions for self-powered wireless sensing, JOURNAL OF PHYSICS D-APPLIED PHYSICS, Vol: 56, ISSN: 0022-3727

Journal article

Lu Z-Q, Zhang F-Y, Fu H-L, Ding H, Chen L-Qet al., 2022, Rotational nonlinear double-beam energy harvesting, SMART MATERIALS AND STRUCTURES, Vol: 31, ISSN: 0964-1726

Journal article

Rao J, Wang J, Kollmannsberger S, Shi J, Fu H, Rank Eet al., 2022, Point cloud-based elastic reverse time migration for ultrasonic imaging of components with vertical surfaces, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, Vol: 163, ISSN: 0888-3270

Journal article

Fu H, Rao J, Harb MS, Theodossiades Set al., 2021, Ultrasonic wireless power links for battery-free condition monitoring in metallic enclosures, ULTRASONICS, Vol: 114, ISSN: 0041-624X

Journal article

Fu H, Mei X, Yurchenko D, Zhou S, Theodossiades S, Nakano K, Yeatman EMet al., 2021, Rotational energy harvesting for self-powered sensing, JOULE, Vol: 5, Pages: 1074-1118, ISSN: 2542-4351

Journal article

Ding K, Zhang Y, Chan FTS, Zhang C, Lv J, Liu Q, Leng J, Fu Het al., 2021, A cyber-physical production monitoring service system for energy-aware collaborative production monitoring in a smart shop floor, JOURNAL OF CLEANER PRODUCTION, Vol: 297, ISSN: 0959-6526

Journal article

Fu H, Zhang Y, Liu M, Qin Y, Yeatman EMet al., 2021, A BISTABLE ENERGY HARVESTER FOR SELF-POWERED SENSING IN RAIL TRANSPORT CONDITION MONITORING, 21st International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers), Publisher: IEEE, Pages: 140-143, ISSN: 2167-0013

Conference paper

Masabi SN, Fu H, Theodossiades S, 2021, AN ULTRA-LOW FREQUENCY MAGNET-TETHERED VIBRATION ENERGY HARVESTER FOR SELF-POWERED SENSING, 21st International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers), Publisher: IEEE, Pages: 956-959, ISSN: 2167-0013

Conference paper

Liu H, Fu H, Sun L, Lee C, Yeatman EMet al., 2020, Hybrid energy harvesting technology: From materials, structural design, system integration to applications, Renewable and Sustainable Energy Reviews, Pages: 110473-110473, ISSN: 1364-0321

Journal article

Fu H, Theodossiades S, Gunn B, Abdallah I, Chatzi Eet al., 2020, Ultra-low frequency energy harvesting using bi-stability and rotary-translational motion in a magnet-tethered oscillator, NONLINEAR DYNAMICS, Vol: 101, Pages: 2131-2143, ISSN: 0924-090X

Journal article

Tabian I, Fu H, Khodaei ZS, 2020, Impact detection on composite plates based on convolution neural network, Pages: 476-481, ISSN: 1013-9826

This paper presents a novel Convolutional Neural Network (CNN) based metamodel for impact detection and characterization for a Structural Health Monitoring (SHM) application. The signals recorded by PZT sensors during various impact events on a composite plate is used as inputs to CNN to detect and locate impact events. The input of the metamodel consists of 2D images, constructed from the signals recorded from a network of sensors. The developed meta-model was then developed and tested on a composite plate. The results show that the CNN-based metamodel is capable of detecting impacts with more than 98% accuracy. In addition, the network was capable of detecting impacts in the other regions of the panel, which was not trained with but had similar geometric configuration. The accuracy in this case was also above 98%, showing the scalability of this method for large complex structures of repeating zones such as composite stiffened panel.

Conference paper

Fu H, Song W, Qin Y, Yeatman EMet al., 2020, Broadband Vibration Energy Harvesting from Underground Trains for Self-Powered Condition Monitoring, 19th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (Power MEMS), Publisher: IEEE

Conference paper

Iuliana T, Fu H, Sharif Khodaei Z, 2019, A convolutional neural network for impact detection and characterization of complex composite structures, Sensors, Vol: 19, ISSN: 1424-8220

This paper reports on a novel metamodel for impact detection, localization and characterization of complex composite structures based on Convolutional Neural Networks (CNN) and passive sensing. Methods to generate appropriate input datasets and network architectures for impact localization and characterization were proposed, investigated and optimized. The ultrasonic waves generated by external impact events and recorded by piezoelectric sensors are transferred to 2D images which are used for impact detection and characterization. The accuracy of the detection was tested on a composite fuselage panel which was shown to be over 94%. In addition, the scalability of this metamodelling technique has been investigated by training the CNN metamodels with the data from part of the stiffened panel and testing the performance on other sections with similar geometry. Impacts were detected with an accuracy of over 95%. Impact energy levels were also successfully categorized while trained at coupon level and applied to sub-components with greater complexity. These results validated the applicability of the proposed CNN-based metamodel to real-life application such as composite aircraft parts.

Journal article

Fu H, Sharif Khodaei Z, Aliabadi M, 2019, An energy-efficient cyber-physical system for wireless on-board aircraft structural health monitoring, Mechanical Systems and Signal Processing, Vol: 128, Pages: 352-368, ISSN: 0888-3270

In this paper, an energy-efficient cyber-physical system using piezoelectric transducers (PZTs) and wireless sensor networks (WSN) is proposed, designed and experimentally validated for on-board aircraft structural health monitoring (SHM). A WSN is exploited to coordinate damage detection using PZTs distributed on the whole aircraft. An active sensing methodology is adopted for PZTs to evaluate the structural integrity in a pitch-catch manner. The system configuration and operation principle are discussed in the first place. Then, the detailed hardware design was introduced. The proposed system is not only characterized as low-power, high-compactness and wireless, but also capable of processing actuating-sensing signals at megahertz, generating actuating signals with great flexibility, handling multiple actuating-sensing channels with marginal crosstalk. The design was implemented on a 4-layer printed circuit board (8 × 6.5 cm) and evaluated on a large-scale composite fuselage. A 5 MHz sampling rate for actuating and 1.8 MHz for sensing (8 channels) were realized, and the accuracy was validated by comparing the results with those from an oscilloscope. The crosstalk issue caused by actuation on sensing channels is properly addressed using a 2-stage attenuation method. An ultra-low current (81.7 μA) was measured when no detection was required; the average current was 0.45 mA with a detection rate of twice per hour, which means the system can continuously work for up to 12.6 months for 2 AA batteries. Eventually, an example of damage detection is provided, showing the capability of such a system in SHM.

Journal article

Fu H, Yeatman E, 2019, Rotational energy harvesting using bi-stability and frequency up-conversion for low-power sensing applications: Theoretical modelling and experimental validation., Mechanical Systems and Signal Processing, Vol: 125, Pages: 229-244, ISSN: 0888-3270

Abstract Kinetic energy harvesting has drawn great attention in the past decade, but low-frequency and broadband operation is still a big issue which impedes this technology to be widely deployed in low-power Internet of Things applications. In this paper, theoretical modelling and experimental validation of a rotational harvester with bi-stability and frequency up-conversion is presented for harnessing low-frequency kinetic energy with a wide bandwidth. Piezoelectric transduction was adopted to convert the rotational kinetic energy into electricity. Distributed-parameter modelling was employed for analyzing the electromechanical dynamics of the bistable piezoelectric beam. Bistable and frequency up-converting behaviours were considered in the theoretical model by introducing two external input magnetic forces. Different oscillating modes were analyzed, showing the variation of power generation capability under different modes, and the advantage of operating in the periodic double-well mode. From the potential well study, we got a conclusion that for the same input magnetic force, periodic double-well mode is capable of achieving a larger vibration amplitude compared to a harvester without bi-stability. Asymmetric potential well shapes were investigated. This asymmetric shape provides a way to stabilize the initiation position of the beam for each plucking cycle, and eventually to stabilized the output. Key design factors to control the oscillating modes were studied, providing a guideline for future design. An experimental study was conducted to verify the theoretical results. A close match was achieved. This bistable harvester demonstrated a significant improvement (up to 2 × ) compared to a harvester without bi-stability over a wide bandwidth (from 1 to 11 Hz) at low frequencies, when operating in the periodic double-well mode. This paper presents a detailed theoretical model and in-depth analysis of a bistable frequency up-converting harvester, providing a

Journal article

Fu H, Zhou S, Yeatman E, 2019, Exploring coupled electromechanical non-linearities for broadband energy harvesting from low-frequency rotational sources, Smart Materials and Structures, Vol: 28, ISSN: 0964-1726

This paper presents a methodology to effectively harness low-frequency broadband rotational energy using coupled electromechanical non-linearities. This design integrates bi-stability and a synchronized switch harvesting on inductor (SSHI) circuit into a frequency up-converting harvester. The bistable behaviour enables improved output power due to the increased vibration amplitude under the same input plucking force. The SSHI circuit exhibits enhanced conversion capability, contributing higher electrical damping which is ideal for frequency up-converting harvesters to alleviate output fluctuation at high frequencies. To study the coupled non-linear dynamics from both the mechanical (bi-stability) and electrical (SSHI) sides, a system-level theoretical model is, for the first time, established and numerically solved using Matlab/Simulink. System behaviours, which would not be able to obtain using circuit simulation methods, are studied for different operating frequencies and load resistances. To validate the theoretical analysis, this harvester was implemented and tested experimentally. A close match was obtained. From the experimental results, an enhanced output power (up to 525%), over a broad frequency range, was realized, compared to that of a harvester with neither bi-stability nor SSHI circuits.

Journal article

Fu H, Sharif Khodaei Z, Aliabadi M, 2019, A bio-inspired host-parasite structure for broadband vibration energy harvesting from low-frequency random sources, Applied Physics Letters, Vol: 114, ISSN: 0003-6951

Energy harvesting for low-power sensing has drawn great attention, but still faces challenges in harnessing broadband random motions. Inspired by the parasitic relationship in plants, a host-parasite vibration harvester is designed to scavenge random low-frequency vibrations by incorporating bi-stability and frequency up-conversion within such a design. A hosting beam is formed in a buckled condition by clamping it at both ends and applying an axial compression load. Two parasitic piezoelectric beams are fixed at the center of the hosting beam and plucked at the free ends by two plectra on the hosting beam, while it oscillates in an inter-well mode. The low-frequency hosting beam oscillation is converted to high-frequency parasitic beam's vibration at resonance due to the plucking effect, allowing the harvester to convert the broadband low-frequency motion into electricity effectively. The electromechanical dynamics are modeled and the design is validated experimentally. The harvester is capable of harnessing low-frequency random vibration (0.0018 g2/Hz @ 5–400 Hz) over a wide bandwidth. More than 1 mJ energy was collected over 100 s under this pseudorandom vibration.Energy harvesting has been recognized as one of the key enablers for self-powered sensing applications in the era of Internet of things.1–4 However, enhancing the energy harvesting effectiveness requires significant efforts, especially for different energy sources under various conditions, such as low-frequency human motion,5,6 random aircraft vibrations7 or ocean waves.8 Harnessing a random, broadband and low-frequency kinetic energy is one of the key challenges, and different mechanisms have been developed to enhance the conversion performance.Nonlinear dynamics are one major consideration to enhance the operation bandwidth.9–11 Different harvesters have been developed with monostable,12–14 bistable15–17 and multistable behaviors.18–20 The aim is to al

Journal article

Fu H, Sharif Khodaei Z, Aliabadi MH, 2019, An energy efficient wireless module for on-board aircraft impact detection, Nondestructive Characterization and Monitoring of Advanced Materials, Aerospace, Civil Infrastructure, and Transportation XIII, Publisher: Society of Photo-optical Instrumentation Engineers, ISSN: 0277-786X

An innovative wireless passive system for impact detection on large-scale composite airframe structures is presented. The wireless system is designed to operate with a sensor network for onboard of aircraft for structural health monitoring, of composite airframe. The wireless systems efficient design allows for low power consumption, wireless communication capability, system robustness and large sensing area. The system is evaluated on a large-scale stiffened composite fuselage under different operational conditions. It is demonstrated that it is possible to detect impact events with different impact energy levels and impact locations over a large monitoring area. This work provides a potential solution for aircraft on-board structural health monitoring with no human intervention. This sensing system can be also adapted to other Internet of Things and structural health monitoring applications.

Conference paper

Fu H, Sharif Khodaei Z, Aliabadi MH, 2019, An event-triggered energy-efficient wireless structural health monitoring system for impact detection in composite airframes, IEEE Internet of Things Journal, Vol: 6, Pages: 1183-1192, ISSN: 2327-4662

In this paper, a low-power high-response wireless structural health monitoring system (WSHMS) is designed, implemented and experimentally evaluated for impact detection in composite airframes. Due to the rare, random and transitory nature of impacts, an event-triggered mechanism is adopted for allowing the system to exhibit low power consumption when no impact occurs and high performance when triggered. System responsiveness, robustness and energy efficiency are considered and modelled. Based on system requirements and functions, several modules are designed, including filtering, impact detecting, local processing and wireless communicating modules. The system was implemented on a printed circuit board. The response time is about 12 us with an average current lower than 1 mA when the impact activity is lower than 0.1%. The system exhibits high robustness to ambient vibration noises and is also capable of accurately and responsively capturing multiple sensing input channels (up to 24 channels). This work presents a low-latency energy-aware WSHMS for impact detection of composite structures. It can be adapted to monitor of other rare, random and ephemeral events in many Internet of Things applications.

Journal article

Fu H, Khodaei ZS, Aliabadi MHF, 2019, BROADBAND ENERGY HARVESTING USING BI-STABILITY AND FREQUENCY UP-CONVERSION FOR SELF-POWERED SENSING IN INTERNET OF THINGS, 20th International Conference on Solid-State Sensors, Actuators and Microsystems and Eurosensors XXXIII (TRANSDUCERS and EUROSENSORS), Publisher: IEEE, Pages: 354-357

Conference paper

Fu H, Yeatman E, 2018, Comparison and scaling effects of rotational micro‐generators using electromagnetic and piezoelectric transduction, Energy Technology, Vol: 6, ISSN: 2194-4296

Rotational energy is widely distributed or easily acquirable from other energy sources (fluid flow, machine operation or human motion) in many industrial and domestic scenarios. At small scales, power generation from such rotational ambient sources can enable many autonomous and self‐reliant sensing applications. In this paper, three typical types of micro‐generators (energy harvesters), namely electromagnetic (EMREHs), piezoelectric resonant (PRREHs) and piezoelectric non‐resonant rotational energy harvesters (PNRREHs) are discussed and compared in terms of device dimensions and operation frequencies. Theoretical models are established for each type to calculate maximum achievable output power as a function of device dimension and operating frequency. Using these theoretical models, scaling laws are established for each type to estimate the achievable output. The EMREHs have a strong scaling effect both on device dimension (as L5) and on operating frequency (as ω2), whereas the PNRREHs are less so (L2.5ω0.5). PRREHs have a narrow band‐width as resonant harvesters, and are ideal for cases where the excitation frequency is constant. This study provides a guideline for selection and design of rotational energy harvesters (REHs) when the device dimension and operating frequency are defined. The proposed scaling laws offer a convenient method to estimate the harvester performance for different dimensions and operating frequencies.

Journal article

Fu H, Hami Seno A, Sharif Khodaei Z, Aliabadi MHet al., 2018, Design of a wireless passive sensing system for impact detection of aerospace composite structures, 2018 5th IEEE International Workshop on Metrology for AeroSpace (MetroAeroSpace), Publisher: IEEE, Pages: 585-589, ISSN: 2575-7490

In this paper, the design and implementation of a novel on-board wireless passive sensing system for impact detection of composite airframe is presented for the first time. Several modules, including filtering, impact detection, local processing and wireless transmission are designed and evaluated for detecting rare, random and transitory impact events. An event-triggered mechanism with high responsiveness is adopted to reduce the system power dissipation and to maintain the detection effectiveness. This design allows the system to be adaptive, energy-efficient and highly responsive to impacts. The whole system was implemented in an experimental study, and the effectiveness was evaluated and illustrated. The system was woken up by impact events in around 12 µs, and the impact data were recorded at 200 kHz (up to 5.33 MHz). This work provides a guideline for low-power, high-responsiveness passive on-board sensing system design. This system can also be adapted to other sensing applications in aerospace engineering.

Conference paper

Fu H, Yeatman EM, 2018, Effective piezoelectric energy harvesting using beam plucking and a synchronized switch harvesting circuit, Smart Materials and Structures, Vol: 27, Pages: 084003-084003, ISSN: 0964-1726

Journal article

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