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Railway traffic plays a pivotal role within the current transportation system, with ensuring its safety being of paramount importance. Real-time monitoring of train track health through sensor technology has emerged as a significant approach for achieving this objective. However, a persistent challenge lies in providing cost-effective and stable power to sensors in remote areas. This paper proposes the utilization of a novel piezoelectric stack energy harvester in railway systems to address this issue. The substantial and consistent vibration energy produced by railway operations makes it an ideal source for energy harvesting, unaffected by environmental conditions. Through simulation analysis and experimental verification, this study explores the impact of load size, load frequency, and external resistance on the energy harvesting efficiency of the proposed piezoelectric stack energy harvester. The results indicate that the output power of the energy harvester increases with the load size. Furthermore, the frequency significantly influences the energy capture efficiency when below 8 Hz, with minimal impact on frequencies above 8 Hz. Interestingly, the load dramatically affects the energy capture efficiency, even at higher frequencies. With the external resistance set to 250 kΩ, the harvester achieves a maximum output power of 42.76 mW. [ABSTRACT FROM AUTHOR]

Batteries with a limited lifespan have gradually failed to meet the development needs of some low-power electronic products. Harvesting wind energy to power the above devices has been a promising way. Facing the time-varying characteristics of wind direction and velocity in the natural environment, an efficient orientation-adaptive energy harvester (OAEH) based on the piezoelectric effect is proposed. An experimental test system is established to probe into the output and adaptive performances of the OAEH. The experimental results indicate that improving the inertia of the tray can abate the initial wind velocity and enhance the output power to a certain extent. The relative deviation (γ) of power integration areas at different inclinations is less than 3%. The harvester has 364.86% enhancement in average power integration area comparing that with the fixed shaft. Besides, the OAEH can drive a monitoring device with a display screen and integrated sensors, which can be utilized to monitor the condition of the bridge, flyover, and so on. [ABSTRACT FROM AUTHOR]

This paper proposes a quasi-zero stiffness (QZS) isolator composed of a curved beam (as spider foot) and a linear spring (as spider muscle) inspired by the precise capturing ability of spiders in vibrating environments. The curved beam is simplified as an inclined horizontal spring, and a static analysis is carried out to explore the effects of different structural parameters on the stiffness performance of the QZS isolator. The finite element simulation analysis verifies that the QZS isolator can significantly reduce the first-order natural frequency under the load in the QZS region. The harmonic balance method (HBM) is used to explore the effects of the excitation amplitude, damping ratio, and stiffness coefficient on the system's amplitude-frequency response and transmissibility performance, and the accuracy of the analytical results is verified by the fourth-order Runge-Kutta integral method (RK-4). The experimental data of the QZS isolator prototype are fitted to a nine-degree polynomial, and the RK-4 can theoretically predict the experimental results. The experimental results show that the QZS isolator has a lower initial isolation frequency and a wider isolation frequency bandwidth than the equivalent linear isolator. The frequency sweep test of prototypes with different harmonic excitation amplitudes shows that the initial isolation frequency of the QZS isolator is 3 Hz, and it can isolate 90% of the excitation signal at 7 Hz. The proposed biomimetic spider-like QZS isolator has high application prospects and can provide a reference for optimizing low-frequency or ultra-low-frequency isolators. [ABSTRACT FROM AUTHOR]

This paper proposes a quasi-zero stiffness (QZS) isolator based on an inclined trapezoidal beam to explore its advantages in low-frequency passive vibration isolation. The nonlinear stiffness of the inclined trapezoidal beam due to the buckling effect is investigated through finite element simulation, and a linear positive stiffness spring is connected in parallel to form a QZS isolator with high-static and low-dynamic stiffness performance. The natural frequency of the isolator in the QZS region is simulated and analyzed, and the dynamic response of the QZS isolator under different damping ratios, excitation and load conditions is explored. The prototype of the QZS isolator was manufactured, and a static compression experiment was conducted to obtain its nonlinear stiffness. The dynamic experiment results verify the correctness of the simulation conclusions. The simulation and experimental data demonstrate that the QZS isolator has the characteristics of lower initial isolation frequency compared with the equivalent linear isolator. The proposed QZS isolator has an initial isolation frequency of 2.91 Hz and achieves a 90% isolation efficiency at 7.02 Hz. The proposed QZS isolator has great application prospects and can provide a reference for optimizing low-frequency or ultra-low-frequency isolators. [ABSTRACT FROM AUTHOR]

As one of the most important modes of transportation, the safety of running trains and railway tracks is significant. It is essential to power sensors that detect and track health in remote areas. The vibration energy of the track structure is enormous, stable, and not limited by weather factors such as the sun and wind. A new type of arch beam piezoelectric stack energy harvester for railway systems is studied in this paper. Through simulation analyses and experimental verification of the energy harvester, the influences of external resistance, load, pre-stress, and load frequency on the energy harvesting performance of the piezoelectric energy harvester are discussed. When the frequency is less than 6 Hz, the energy capture efficiency is greatly affected by the frequency. When the frequency exceeds 6 Hz, the frequency has little effect and the load dramatically affects the energy capture efficiency. The pre-stress has little effect on the energy capture efficiency, but there is an optimal value at 4.5 kN. The energy harvester has an output power of 193 mW, a weight of 912 g, and the energy density can reach 211.8 μW/g. These results can provide a reference for subsequent experiments in the actual environment. [ABSTRACT FROM AUTHOR]