Rail corrugation inspection by a self-contained triple-repellent electromagnetic energy harvesting system

Rail corrugation, a widely distributed periodic wear pattern of the railway track, is a severe rail defect that could cause high-pitched noises and vibrations of the ground and nearby buildings. The current rail corrugation inspection trolley can only be employed offline, whereas online monitoring devices require external batteries that depend heavily on manual maintenance. This paper presents a novel approach by monitoring the rail corrugation online using a self-contained energy harvesting system. The mechanics of the magnetic-floating energy harvester was improved by a triple-magnet configuration, and differences between repellent and attractive configurations were investigated. Comprehensive broad-band (5–2000 Hz) sinusoidal sweeping vibration tests and stochastic vibration tests were conducted based on the measured railway track spectra. The wavelet theory was used to carry out time–frequency analysis and identify the defects of the rail corrugation. The results indicate that the proposed system could collect the rail vibration energy across a wider frequency range as well as identify the rail corrugation by the induced voltage of the energy harvesters. This study offers a new sustainable approach toward rail corrugation monitoring by the self-contained energy harvesting system that could eliminate environmentally-unfriendly batteries and reduce manual involvement for railway track inspection.