Non-contact ultrasonic detection of rail surface defects in different depths

Rail inspection using laser ultrasonic surface waves could provide a more reliable and efficient detection of surface cracks. This paper explored the interaction and propagation of Rayleigh waves with cracks which had a wide range of depths relative to the rail surface by finite element 2D model. A non-contact laser generation and detection system was established to detect depth defects. The time and frequency analysis of different depth defect signals are analyzed by simulation and experiment, and the quantitative evaluation of the surface defects in different depths are realized by fitting the relationship between damage factors - damage depths curve. It is found that surface waves are sensitive to shallow cracks and the larger the damage depth is, the larger the damage factor.