Article
Chemistry, Physical
Sangryun Lee, Wonjae Choi, Jeong Won Park, Dae-Su Kim, Sahn Nahm, Wonju Jeon, Grace X. Gu, Miso Kim, Seunghwa Ryu
Summary: In this study, we propose a gradient-index (GRIN) phononic crystal (PnC) design based on machine learning optimization, which achieves maximum elastic wave focusing and harvesting. By training a deep neural network (NN), new hole shapes with improved focusing performance are derived and the NN is updated through active learning. The optimized GRIN PnC design exhibits 3.06 times higher wave energy intensity compared to the conventional design and is validated through experiments.
Article
Engineering, Mechanical
Zhihui Wen, Shixuan Zeng, Dongwei Wang, Yabin Jin, Bahram Djafari-Rouhani
Summary: This paper introduces a method to achieve strong robustness in elastic wave routing at subwavelength scale through chiral edge states, which exhibit stronger resistance to defects and perturbations. The energy harvesting powers of chiral mechanical systems show higher robustness against frequency disorder and position disorder compared to C6v designs.
EXTREME MECHANICS LETTERS
(2021)
Article
Engineering, Mechanical
Yuping Tian, Wei Zhang, Zhuhua Tan, Chongdu Cho
Summary: Chiral materials provide a new platform for wave manipulation, with the potential to control elastic waves and achieve robust energy harvesting. By constructing chiral phononic crystals, strong edge states can be induced, and efficient energy harvesting can be achieved at piezoelectric positions on the material edges.
EXTREME MECHANICS LETTERS
(2022)
Review
Chemistry, Multidisciplinary
Mourad Oudich, Nikhil J. R. K. Gerard, Yuanchen Deng, Yun Jing
Summary: In solid state physics, a bandgap refers to a range of energies where no electronic states can exist. This concept has been extended to classical waves, giving rise to photonic and phononic crystals. In elastic waves, bandgaps are found in materials with periodic alternating mechanical properties, leading to the development of elastic metamaterials and phononic crystals. The rise of topological insulators and the advancement of additive manufacturing have further expanded the functionalities of these manmade materials.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Energy & Fuels
Binsheng Li, Hui Chen, Baizhan Xia, Lingyun Yao
Summary: Recently, topological phononic crystals have been widely used for designing acoustic energy harvesting devices, which benefit from the robustness of the topological state. However, these devices often operate at excessively high frequencies. To address this issue, this study proposes a novel acoustic energy harvesting device based on the topological edge state of a multi-resonant phononic crystal. By introducing multiple resonant cavities, the device achieves improved robustness and reduced operating frequency. The theoretical model of the device is established and the robustness of the edge states is verified through finite element method (FEM) simulations. The results demonstrate that the device effectively collects acoustic energy, with maximum output voltage observed at an incident frequency of 718 Hz and a maximum voltage amplitude of 132.5 mV. Additionally, even with point defects, the device still demonstrates good acoustic energy collection capability, with a maximum voltage of 96.5 mV at 707 Hz. In conclusion, the topological edge state of a multi-resonant phononic crystal can be designed as an excellent acoustic energy harvesting device due to its lower operating frequency and improved design robustness.
Article
Engineering, Mechanical
Wei Ding, Tianning Chen, Chen Chen, Dimitrios Chronopoulos, Jian Zhu, Badreddine Assouar
Summary: We report a planar chiral phononic crystal based on Thomson scattering that can open a broadband gap by discarding the local resonant sub-structure. By simplifying the material components, we lower the starting frequency while maintaining the width of the bandgap. This finding provides a new way to manipulate broadband elastic waves and validates Thomson scattering as a promising alternative approach for bandgap formation.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2022)
Article
Chemistry, Physical
Sangtae Kim, Jaehoon Choi, Hong Min Seung, Inki Jung, Ki Hoon Ryu, Hyun-Cheol Song, Chong-Yun Kang, Miso Kim
Summary: This study combines Helmholtz resonance and omnidirectional acoustic wave focusing to generate high power output at low frequencies in ambient sound environments. A two-degree-of-freedom model is used to design a HR integrated with a piezoelectric device, which is then combined with a circularly symmetric gradient index phononic crystal structure for omnidirectional sound focusing. The coupled acoustic system GRIN-HR-PEH demonstrates flexibility in design and achieved an output power of up to 4.1 mW under ambient sound pressure of 47 dB.
Review
Materials Science, Multidisciplinary
Christabel Choi, Shubhi Bansal, Niko Munzenrieder, Sriram Subramanian
Summary: Acoustic metamaterials and phononic crystals have the potential to revolutionize human interactions and sensory communications. Understanding the fundamental theory and design principles alone is not enough; physical realization of these structures through fabrication and assembly is equally important. The paper critically examines fabrication and assembly approaches, addressing crucial parameters for efficient structural implementation. Various assembly techniques are proposed, uncovering innovative designs and supporting a fresh paradigm for innovation.
ADVANCED ENGINEERING MATERIALS
(2021)
Review
Nanoscience & Nanotechnology
Yabin Jin, Liangshu He, Zhihui Wen, Bohayra Mortazavi, Hongwei Guo, Daniel Torrent, Bahram Djafari-Rouhani, Timon Rabczuk, Xiaoying Zhuang, Yan Li
Summary: With the growing interest in artificial materials, the demand for advanced functionalities in phononic crystals and acoustic metamaterials is increasing. Machine learning, as an important branch of artificial intelligence, provides a powerful means of achieving efficient and accurate design processes. This review summarizes recent works on the combination of phononic metamaterials and machine learning and provides an outlook on future development directions.
Article
Chemistry, Physical
Liang Zhang, Ting Tan, Zhengyue Yu, Zhimiao Yan
Summary: This study proposes a method to improve the localization of elastic waves in phononic crystals by introducing topological imbalance and semi-enclosed defects. Parametric equations are used to generate lattice unit cells with topological evolution and band gap widening is achieved by increasing topological imbalance. Experimental results show that phononic crystals with semi-enclosed line defects have the best energy confinement effect.
Article
Physics, Applied
Oluwaseyi Muhammad, Oluwaseyi Ogun, John Kennedy
Summary: This study developed a deep learning based autoencoder to inversely design topological phononic beams. By studying the topologically protected interface state, the characteristics of the interface modes were determined. The network prediction was validated by finite element numerical simulations and experimental tests.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Crystallography
Jianning Han, Guodong Hao, Wenying Yang, Xinsa Zhao
Summary: In the field of industrial structure detection, acoustic signals play a pivotal role. This study proposes a structure (PC-Mie) that couples phononic crystal (PC) point defects and Mie resonance structures (Mies) to enhance weak effective signals from complex environments. Numerical and experimental studies demonstrate that the PC-Mie can effectively enhance the energy of specific sound frequencies in complex air environments, making it suitable for collecting high-sensitivity acoustic signals. This research has significant implications for the development of weak acoustic signal detection technology and the application of self-powered sensors.
Article
Physics, Multidisciplinary
Liangshu He, Hongwei Guo, Yabin Jin, Xiaoying Zhuang, Timon Rabczuk, Yan Li
Summary: This study demonstrates how machine learning can be used to study phononic crystal beams through two inverse design schemes. It provides a method for inverse design of structural parameters to maximize the bandgap width and uses a neural network to solve the training difficulty problem and achieve inverse structure design with targeted topological properties.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(2022)
Article
Engineering, Civil
Yingli Li, Shiguang Yan, Yong Peng
Summary: The study proposed a single-phase 2D phononic crystal structure with tetragonal topology and cross-like pores, and both numerical simulation and theoretical analysis were performed to investigate the formation and regulation mechanism of bandgap and obtain broadband vibration attenuation capability. The results showed that X-shaped pores led to multiband and broadband characteristics, while cross-shaped pores opened wide bandgaps at low frequencies. The analytical formulations derived from structural mechanics accurately predicted the bandgap edge frequencies and provided effective guidance for bandgap tuning and structural design. Additionally, combining structures with different mass distributions enhanced the vibration mitigation capability. The lighter and easier fabricatable structure proposed in this study provided significant guidance for the design of tunable phononic devices.
THIN-WALLED STRUCTURES
(2023)
Article
Multidisciplinary Sciences
Farzaneh Motaei, Ali Bahrami
Summary: In this study, a phononic crystal-based fiber is proposed for energy harvesting in metalworking factories. The fiber structure includes a tungsten hollow cylinder in the center and has high confinement and transmission ability. Mechanical energy is converted to electrical energy using a piezoelectric film attached to the fiber cores, resulting in significantly enhanced output power.
SCIENTIFIC REPORTS
(2022)
Article
Engineering, Mechanical
Liuyang Xiong, Lihua Tang
Summary: This study investigates the mode veering and mode localization behavior of a coupled micro-cantilever system with mass disturbances. A new sensitivity metric is proposed and validated through numerical and finite element analyses, as well as experimental study. The results show the superior linearity and effectiveness of the derived sensitivity metric, and reveal the influence of damping and coupling factor on mass sensing resolution.
JOURNAL OF VIBRATION ENGINEERING & TECHNOLOGIES
(2023)
Article
Engineering, Civil
Shaohua Wang, Hao Zheng, Lihua Tang, Zhaoyu Li, Renda Zhao, Yuqian Lu, Kean C. Aw
Summary: This study investigates the feasibility of using computer vision-aided health condition monitoring approach for rail track structures based on vibration signals. The proposed method converts vibration signals into grayscale images and extracts image features to establish a Visual Bag-of-Words model. The health condition of track structures is recognized by comparing the Euclidean distance between word frequency vectors. The results demonstrate high recognition accuracy and low bias, showing promising application prospects in early-stage structural defect detection.
JOURNAL OF CIVIL STRUCTURAL HEALTH MONITORING
(2023)
Article
Engineering, Electrical & Electronic
Zhiwu Xie, Li Teng, Yu Yin, Junrui Liang
Summary: The synchronous switch technique is a promising solution to improve the energy harvesting capabilities of piezoelectric devices and electromagnetic sources. This brief introduces a synchronous switch energy extraction (SSEE) circuit and examines its performance in motor regenerative braking enhancement. By connecting a switched capacitive branch to compensate for the inductive source of an electromagnetic motor, the SSEE significantly improves the braking power and extracts kinetic energy faster. Experimental results show that the SSEE can recover 182.5% more energy than the diode-bridge rectifier and reduce the braking time by 35.1% compared to short-circuit braking.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS
(2023)
Article
Engineering, Electrical & Electronic
Chaoqun Qi, Guangce Zheng, Yu Liu, Junrui Liang, Haoyu Wang, Minfan Fu
Summary: Capacitive power transfer is a promising method for high-efficiency wireless charging. This letter focuses on the modeling and simplification of the high-order system using series compensation, reducing the number of resonant components from ten to two. By combining with the inverter and rectifier model, a third-order equivalent circuit model for the whole system is derived with clear physical meaning and explicit transfer function. Experimental results show the accuracy of the model up to 1/5 of the switching frequency.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Physics, Applied
Yi Huang, Guobiao Hu, Chaoyang Zhao, Baoping Tang, Xiaojing Mu, Yaowen Yang
Summary: A novel L-shaped self-adaptive piezoelectric energy harvester (LSA-PEH) with a slider is proposed in this study for harvesting vibration energy. A linearized mathematical model is established to predict the resonant frequency of the LSA-PEH based on the position of the slider. Experimental results show that the slider of the proposed LSA-PEH can passively relocate its position to adjust its resonant frequency and maintain resonance. The proposed LSA-PEH has a 350% increased bandwidth compared to a conventional L-shaped beam harvester.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Jinling Zhu, Hailiang Yang, Leitao Cao, Chenchen Dai, Jing Ren, Junrui Liang, Shengjie Ling
Summary: This work presents a non-destructive technique to functionalize structural materials by selectively etching their surface without compromising their internal structure. An ultrathin and transparent silk fibroin ionotronic nanofiber skin (SFINS) is electro-spun onto the surface of the materials, giving them electric conductivity and environmental responsiveness. This technique offers scalability, cost-effectiveness, and high efficiency, without altering the structure, properties, and sustainability of the substrate materials.
Article
Automation & Control Systems
Linglong Gao, Li Teng, Minfan Fu, Haoyu Wang, Junrui Liang
Summary: This article proposes a compact self-sensing synchronized switch interface for piezoelectric energy harvesting. The interface circuit uses a modified buck-boost topology and implements time-sharing control. It works in strong discontinuous conduction mode and extracts a small amount of charge from the piezoelectric transducer for sensing, while extracting charge at a higher intensity for energy harvesting. The self-sensing mechanism is studied theoretically and validated through experiments.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Zhiwu Xie, Li Teng, Haoyu Wang, Yu Liu, Minfan Fu, Junrui Liang
Summary: This article proposes a self-powered synchronous switch energy extraction (SP-SSEE) circuit for inductive electromagnetic energy harvesting sources. The circuit uses a small series sampling inductor, a comparator, and some digital gates for sampling, synchronization, and switch control. By improving the power factor of the induced voltage source, it increases the harvested power under the same excitation. The SP-SSEE circuit uses fewer switching actions than conventional designs and it is more convenient to be utilized in real applications due to its self-powered design.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Mingde Zhou, Chuhan Peng, Junrui Liang, Minfan Fu, Haoyu Wang
Summary: Critical conduction mode (CRM) is widely used in totem-pole Boost power factor correction converters due to its compatibility with soft-switching and high switching frequency. This paper proposes a novel CRM realization method using an inductor current estimator model to estimate the averaged current and predict the current zero crossings. By replacing the noisy sensing signal with estimated values, the need for a zero-current detection circuit is eliminated, simplifying the peripheral circuit design. The proposed control concept is validated on a GaN-based prototype, achieving a peak efficiency of 98.96% and a power factor of 0.9972.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Engineering, Mechanical
Junlei Wang, Ye Zhang, Guobiao Hu, Wenming Zhang
Summary: This paper investigates the wake-induced vibration and heat convection of downstream tandem bluff bodies under the influence of an upstream bluff body at Re = 200 and Pr = 0.7. It reveals that the vibration response is closely related to the fluid velocity and bluff body diameter ratio, and the heat transfer efficiency is influenced by the wake interference and the "blocking effect" from the upstream bluff body. There is a trade-off between heat transfer efficiency and service lifespan, as increasing vibration amplitude enhances convection but increases the risk of potential damage.
JOURNAL OF FLUIDS AND STRUCTURES
(2023)
Article
Engineering, Mechanical
Bao Zhao, Jiahua Wang, Guobiao Hu, Andrea Colombi, Wei-Hsin Liao, Junrui Liang
Summary: Nonlinearity has enabled energy harvesting to advance toward higher power output and broader bandwidth in monostable, bistable, and multistable systems. However, operating in the preferable high-energy orbit (HEO) rather than the low-energy orbit (LEO) for making such advancement has restricted their applications. This paper proposes a self-contained solution for time-sharing orbit jump and energy harvesting using a monostable nonlinear system and a switched-mode bidirectional energy conversion circuit. The proposed solution enhances the practical utility of nonlinear energy harvesting technologies toward engineering applications.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Chemistry, Physical
Liwei Dong, Qian Tang, Chaoyang Zhao, Guobiao Hu, Shuai Qu, Zicheng Liu, Yaowen Yang
Summary: This paper proposes a novel hybrid scheme for flag-type nanogenerators (FNGs) that enhances their performance and broadens their operational wind speed ranges by harnessing the synergistic potential of two aerodynamic behaviors. The proposed flag-type triboelectric-piezoelectric hybrid nanogenerator (FTPNG) integrates flapping piezoelectric flags (PEFs) and a fluttering triboelectric flag (TEF). The FTPNG achieves significant power generation and a broad wind speed range, surpassing other FNGs, making it suitable for various self-powered systems and Internet of Things applications.
Article
Computer Science, Information Systems
Runhui He, Bo Xue, Mingde Zhou, Minfan Fu, Junrui Liang, Yu Liu, Haoyu Wang
Summary: To achieve optimal system performance, LLC resonant converters should be operated at their resonant frequency. However, the resonant parameters can deviate significantly in mass production, necessitating active tracking of the resonant frequency. This paper presents a novel control scheme for LLC converters that tracks the resonant frequency using an accurate small-signal model and an extended state observer. The proposed scheme is easier to implement and requires fewer sensors compared to conventional control schemes, as demonstrated by experimental results.
Article
Computer Science, Information Systems
Kang Yue, Yu Liu, Minfan Fu, Junrui Liang, Haoyu Wang
Summary: This paper proposes a model based method to estimate all the parameters of interest, including mutual inductances, load condition, and all the capacitances, for multi-coil wireless power transfer (WPT) systems. The idea of mode switching is applied to improve the redundancy of the parameter identification problem, and a mathematical model is established to describe the physical laws among all the interested parameters in each mode. The method only requires transmitter side measurements, without any information from the receiver side.
Article
Acoustics
Xiaofei Lyu, Hui Sheng, Mengxin He, Qian Ding, Lihua Tang, Tianzhi Yang
Summary: This letter presents a lightweight whole-spacecraft vibration isolation system with broadband vibration attenuation capability for satellite protection during launch phase. The system design incorporates acoustic black holes (ABHs) as microstructures using the concept of metamaterials/phononic crystals, resulting in significant impedance mismatch and enhanced bandgap effect. Band structure, transmission analyses, as well as hammer and falling tests confirm the ultrawide vibration and shock attenuation ability of the proposed design, indicating its potential for extensive isolation applications.
JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME
(2023)
