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• D-AFB has a simple structure and can easily satisfy QZS conditions. • Customizing the design of D-AFB to adapt to load requirements. • The experiment verified the reliability of replacing D-AFB. • Increasing the number of D-AFB can improve the carrying capacity. • The vibration isolator can stably adapt to load fluctuations within 10 %. There is an increasing demand for integrated small vibration isolators in precision sensing instruments and medical equipment. Therefore, a quasi-zero stiffness (QZS) vibration isolator with double-arc flexible beams (D-AFB) is proposed. The QZS isolator consists of D-AFB units, the base, platform, fixture, guide rail, and linear bearing. The static performance of D-AFB is analyzed using the FEA method, and the QZS condition is obtained. The harmonic balance method (HBM) and the pseudo arc length method (PALM) are used to solve the dynamic equations of the nonlinear system, and the analytical solutions of displacement transmissibility and Force transmissibility are derived. In theory, the initial frequency is 77.6 % lower than that of the equivalent linear system. The QZS characteristic of D-AFB is verified by static experiment, and the low-frequency isolation performance of the QZS isolator is verified by dynamic experiment under constant amplitude and constant acceleration excitation. The D-AFB has a simple structure and can easily satisfy QZS conditions. So the D-AFB can be customized according to load requirements. Multiple vibration isolation loads can be obtained by adjusting the assembly of the D-AFB. The QZS isolator can adapt to load changes within 10 % and has an isolation effect on vibrations above 4 Hz. The idea of designing a QZS isolator with D-AFB as an array unit has a good research prospect and great application value in meeting the requirements of miniaturization and integration. [Display omitted] [ABSTRACT FROM AUTHOR]

Industry 4.0 realizes intelligent interconnection through the sensor group of the Internet of Things. A key challenge is to achieve the self-powering of sensors and stable operation of precision instruments. This paper introduces a dual-functional structure (VIPEH) integrating energy harvesting (EH) and vibration isolation (VI) based on the quasi-zero stiffness (QZS) piezoelectric mechanism. The paper analyzes the nonlinear statics of piezoelectric flexible beams under large deformations and conducts parametric analysis. A nonlinear dynamic model with electromechanical coupling was developed to investigate the impact of mechanical and electrical parameters on the system's dynamic bifurcation behavior, EH, and VI performance. Finally, an experimental setup is created to evaluate the VIPEH's characteristics. Sweep frequency excitation experiments demonstrate that the initial isolation frequency of VIPEH is lower than 1.4 Hz. The important thing is that VIPEH can still power the sensor based on the isolation frequency, and the output power of a single piezoelectric material can reach 3.19 mW. This not only enables the isolation of low-frequency vibrations but also presents a highly promising application for achieving self-powering in sensor clusters within the context of Industry 4.0 and the IoTs. • VIPEH based on quasi-zero stiffness piezoelectric mechanism is proposed. • VIPEH achieves energy harvesting while isolating low-frequency vibrations. • The output power can reach 3.19 mW. • The initial vibration isolation frequency of VIPEH is less than 1.4 Hz. [ABSTRACT FROM AUTHOR]

Ship vibration not only causes safety issues, but also easily generates noise pollution. Therefore, this paper introduces the quasi-zero stiffness (QZS) vibration isolator to solve the problem of low-frequency vibration. In terms of static analysis, this paper proposes a discretized beam constraint model (DBCM) to study the static properties of flexible beams with large deformation, and the finite element analysis (FEA) verifies the accuracy of DBCM. Regarding dynamic analysis, this paper combines the harmonic balance method (HBM) and the pseudo-arc length method (PALM) to analyze the dynamic response and explore the influence of excitation and damping ratio on the response stability. In addition, the performance of equivalent linear isolators is compared, revealing significant advantages of QZS isolator in terms of isolation bandwidth and peak transmissibility. The experimental data demonstrates that QZS isolator's initial isolation frequency (2.14 Hz) is 68.5% lower than that of linear isolators (6.79 Hz), and the isolation efficiency at 5.35 Hz can reach 90%, making it suitable for low-frequency isolation. Furthermore, experimental data validate the accuracy of the theoretical model and FEA. The static and dynamic theoretical models can optimize the structural parameters of flexible beams and serve as valuable inspiration and reference for designing and improving isolator. • The QZS isolator is composed of eight flexible beams and a linear spring. • DBCM can accurately calculate the nonlinear statics of flexible beams. • The QZS isolator has a wider isolation frequency band and lower transmissibility. [ABSTRACT FROM AUTHOR]

• Experiments verified the performance of WMPEH with different structural parameters. • Wake excitation and magnetic coupling are used for underwater energy harvesting. • The wake excitation and magnetic coupling can enhance harvesting performance. • Reducing the fixing column diameter can increase the output voltage. • Increasing the vibrating column diameter can enhance performance. • Increasing the vibrating column mass can improve performance. [Display omitted] This paper proposes a wake-excited magnetically coupled piezoelectric energy harvester (WMPEH) to realize the self-powered function of microelectronic devices in a fluid environment. The WMPEH consists of a fixed column, a vibrating column, magnets, and a piezoelectric composite beam. A series of water tunnel experiments are conducted to prove the usefulness of wake excitation and magnetic coupling, and how it positively or negatively affects the harvester's efficacy. Different fixed and vibrating column diameters and the distance between the two columns affect the performance of the WMPEH. The influence of the wake excitation force generated by the fixed columns with diameters of 5 mm, 10 mm and 15 mm on the vibrating column is analyzed respectively in the experiment. The vibrating column diameter is D , and four different distances are considered, namely 2 D , 3 D , 4 D , and 5 D. The results show that the maximum output voltage of WMPEH is increased by 1.96 and 1.34 times, respectively, compared with that of magnetically coupled piezoelectric energy harvester (MPEH) and conventional piezoelectric energy harvester (PEH). Furthermore, increasing the fixed column diameter leads to a decrease in the output voltage of WMPEH in the case of the same vibrating column diameter. Increasing the diameter and mass of the vibrating column for a specific fixed column diameter can enhance the harvester's performance. The maximum output voltage density of the WMPEH is 75.56 V/cm3 when the vibrating column diameter, the fixed column diameter and the distance between the two columns are 20 mm, 5 mm, and 2 D , respectively. This proposed design can provide the groundwork to promote the performance of the conventional PEH, further enabling the realization of underwater self-powered systems. [ABSTRACT FROM AUTHOR]

This paper designs an underwater magnetic nonlinear piezoelectric energy harvester (PEH) based on the principle of vortex-induced vibration (VIV). The equivalent stiffness of the magnetic nonlinear PEH is significantly changed by varying the relative position of the magnet. It is observed that the proposed PEH displays hardening behavior and softening behavior due to the impact of magnetic forces, which greatly increase the performance of the magnetic nonlinear PEH. The analysis of the results shows that the open-circuit voltage (VRMS) of the hard stiffness system is increased from 9.43 V to 10.31 V, the frequency band is widened by 36.8%, and the efficiency is higher at high flow rates. The initial vibration velocity of the soft stiffness system is reduced. When the water velocity is 0.2 m/s, its VRMS is 10 times that of the classical configuration. Both numerical simulations and experiments prove that the soft stiffness system is more suitable for applications in low-speed water environments. This proposed design can provide the groundwork to promote the performance of the conventional PEH, further enabling to realize self-powered systems. [Display omitted] • An underwater magnetic nonlinear piezoelectric energy harvester is presented. • The position of the magnet has an impact on the performance of the harvester. • The hard stiffness system is suitable for high-velocity water environment. • The soft stiffness system is suitable for low-velocity water environment. [ABSTRACT FROM AUTHOR]

• A bidirectional plucking energy harvester with an orthogonal oscillator is proposed. • Piezoelectric oscillator is excited by bidirectional magnetic component force. • Exploring bending and torsion vibrations of the orthogonal piezoelectric oscillator. • BP-RPEH has multiple resonance regions. • The charge rate could reach 0.39 V/s at 300 rpm. One key challenge of the energy harvesting technology lies in how to fully utilize external environmental excitation to collect ambient energy and convert it into electrical energy efficiently. To address this challenge, this work proposed a bidirectional non-contact plucking rotary piezoelectric energy harvester, based on the spatial distribution characteristics of magnetism. This work was initiated by establishing a mathematical model for the rotating magnetic field and calculating the magnitude of the magnetic forces. Numerical findings indicated that the quantity of rotating magnets had an impact on the magnitude and distribution of these magnetic forces. Leveraging the distinctive attributes of the rotating magnetic forces, this work introduced an orthogonal piezo-oscillator, designed to concurrently respond to magnetic forces along two orthogonal directions. Subsequently, this work conducted experimental research on the piezoelectric oscillators. The experimental results indicated that the number of magnets affects the power output bandwidth and position of the effective frequency. A mathematical relationship exists between the resonant frequency, the number of magnets, and the natural frequency. The results demonstrate that the total peak output power of the harvester could reach 3.29mW calculated by RMS voltage at 301 rpm, and the charging rate could reach 0.39 V/s at 300 rpm. [ABSTRACT FROM AUTHOR]

Vibration energy harvesting holds the promise of providing autonomous power for low-power electronic devices. To improve the issue of the limited bandwidth of the piezoelectric energy harvester, this work proposes a novel T-shaped beam bistable piezoelectric energy harvester with a moving magnet. The moving magnet can not only provide nonlinear force to adjust bandwidth, but also increase the number of system resonance peaks, which improves the utilization of the magnet, enhancing the adaptability of the vibration energy harvesting device to the environment. Established a mathematical model and validated it through experiments. Some parameters, such as external resistance, magnet spacing, and spring stiffness, are analyzed by theoretical analysis. The results indicate that, at an acceleration amplitude of 0.3 g and a frequency of 15.7 Hz, the peak output power of the main support beam is 2.36 mW. Similarly, at an acceleration amplitude of 0.3 g and a frequency of 15.6 Hz, the peak output power of the parasitic cantilever beam is 0.56 mW, demonstrating its potential to power low-power electronic components. The moving magnet provides an additional resonance peak for the harvester, offering a new method for the design of broadband magnetic nonlinear piezoelectric energy harvesters in the near future. • A novel T-shaped beam bistable piezoelectric energy harvester with a moving magnet (TBPEH) is proposed. • The moving magnet can not only provide nonlinear force to adjust bandwidth but also increase the number of system resonance peaks. • The coupling of the moving magnet and the T-shaped beam results in the generation of three voltage peaks, thereby expanding the frequency bandwidth. • The stiffness of the spring and the spacing between magnets influence both the size and position of the resonance peaks excited by the moving magnet. • In laboratory testing, the TBPEH demonstrated the capability to illuminate a light strip comprising 23 LEDs. [ABSTRACT FROM AUTHOR]

Energy harvesters capture the ambient vibration to persistently drive lower-power devices employed in wireless applications. For enhancing the harvesting performance, a novel piezoelectric aeroelastic (piezoaeroelastic) energy harvester fitted with different rod-shaped attachments is presented. The attachments include square and D-shape rods, and symmetrically fixed on airfoil surface at chord maximum thickness. The performance comparisons of various harvesters are conducted by using simulation and experimental methods. The results demonstrate that square and D-shape rods change flow field characteristic and enhance aerodynamic loads, which reduce flutter velocity and broaden the working bandwidth. The harvesters with square and D-shape rods demonstrate the better output characteristic in both aeroelastic vibration and harvesting performance than without rod. Output voltage of the harvester with square rod is up to 15.14 V at airflow velocity of 16.84 m/s and plunge stiffness coefficient of 278 N/m, and the corresponding output power is 0.765 mW. A maximum enhancement ratio of output power for square rod can reach to 469.7 % at 11.1 m/s. The power density of the harvester with square rod is 4.78 mW/cm3, which demonstrates the superior harvesting performance over others. This work provides a significant guidance for designing the more efficient piezoaeroelastic harvester with square rod. [Display omitted] • A novel piezoaeroelastic harvester fitted with rod-shaped attachments is presented. • Rods significantly enhance aerodynamic loads and reduce flutter velocity. • Square rod shows the superior harvesting performance than without and D-shape rods. • A maximum enhancement ratio is up to 469.7 % for square rod. [ABSTRACT FROM AUTHOR]