چكيده به لاتين
In recent years, energy harvesting from natural sources such as vibrations, wind, and sound has gained significant importance in various industries, especially in railway transportation. This energy is crucial for powering sensors, as in many situations, there is no permanent power source available, and battery replacement is costly and challenging. Sensors are key elements in smart monitoring devices, and providing energy to them in remote locations poses an engineering challenge. One solution is energy harvesting devices that generate electrical energy from various sources. Given the critical need for electrical energy to power condition-monitoring sensors in freight trains, the design and construction of a resonator for installation on the axle of a train bogie have been investigated. First, rotational energy harvesters, auxetic structures, and bistable mechanisms are reviewed. Then, a resonator with an auxetic structure is modeled in COMSOL software, and the results are compared with experimental tests. PZT elements are inexpensive, and two circular auxetic layers are proposed to improve their performance. The modeling and experimental results show that energy harvesters with auxetic structures can increase the electrical output of the PZT elements by 13.3 and 10.2 times, respectively. This simple and cost-effective concept can significantly boost the power output required to run condition-monitoring sensors in the railway industry. A laboratory setup, including a motor, shaft, and disk, is created to test resonators with auxetic structures at the rotational frequency of a freight train wheel (6-8 Hz). The studies indicate that auxetic resonators can enhance the performance of rotational energy harvesters by up to 3.28 times. By introducing pre-stress into a clamped beam, a bistable mechanism is created, and by applying an auxetic structure to both ends of the beam and utilizing PZT elements, the output power and energy harvesting efficiency are increased. Furthermore, by increasing the number of resonators and constructing a complete energy harvesting system, the energy required to operate condition-monitoring sensors can be provided. Various parameters, including the electrical circuit and auxetic structure, are optimized through modeling and practical experiments to improve device efficiency.
