In this paper, an enhanced vibrational energy harvesting system for freight wagons is developed by the concept of Auxetic resonators. The novel idea of using Auxetic structures is employed to increase the rate of power conversion by simply changing the structure of the beam without any need to change the geometry of the piezoelectric element or its material. The harvesting system is a resonating cantilever beam, and a piezoelectric element is attached on the beginning section of the beam modeled in Finite Element. Two auxetic patterns are proposed on the beam, exactly under the piezoelectric element. The vibrational input is simulated by modeling the motion of a freight wagon on the railway track using the Universal Mechanism software under different track irregularities and train speeds. The harvesting system is mounted on the axle-box where the vibration intensity received from track irregularity has the highest level. Different track irregularities and train speeds are considered in a parametric study to investigate the performance of the harvesting device. The results show that the application of the Auxetic I and Auxetic II structures enhances the output power by approximately 2 times and 4 times, respectively, compared to the plain beam. Experimental validation further confirmed the numerical results, showing up to 3.5 times improvement in harvested power. These findings demonstrate the potential of auxetic structures for efficient energy harvesting in railway vehicle applications.
Ebrahimian et al. (Sat,) studied this question.