Efficient piezoelectric harvester for random broadband vibration of rail

The railway track dynamic behavior shows intense characteristics in a wide frequency domain, which plays an major role in the generation of wheel-rail rolling noise and the deterioration of track structure. To monitor, study, and control the random vibration of the track system, sensors and harvesters were considered as important techniques of vibration monitoring and energy conversion to maintain the healthy service of railway system. Therefore, effectively scavenging the broadband track vibration energy has significant potential to power trackside monitoring sensor and reduce track vibration. This paper presents an efficient rail-borne piezoelectric energy harvester to collect energy from the random railway vibration in a broad frequency range, and the fractional derivative electromechanical coupling model of the coupled vehicle-track-harvester system was firstly established. The proposed piezoelectric harvester was evaluated by laboratory experiments and theoretical piezoelectric analysis with finite element method. The results indicate that the vibration reduction effect of the efficient rail-borne energy harvester is 196 times greater than the ordinary harvester in high-frequency range. Although the open-circuit voltage can be improved by increasing the thickness of the piezoelectric layer, the maximum output power remains unchanged as 1.03 W/Hz. Constrained by the safety limit of stress and deformation of the piezoelectric material, the harvester can be designed by a programmable methodology according to the rail frequency response in a wide frequency range. The output power peaks at the first two resonance frequencies are obtained as 1036.9 μW/Hz, and 8.01 μW/Hz, respectively, and the maximum values are improved by 3.0 and 15.0 times with comparison to the ordinary harvester, respectively.