A rail defect detection system based on laser Doppler vibrometer measurements

This paper aims at introducing a non-contact rail damage detection system based on laser Doppler vibrometer (LDV) measurements. Specifically, the system consists of two LDVs mounted on a rail car, to record the waves induced on the rail head by random rail-wheel interaction forces.The developed damage detection framework associated with the system is based on a multivariate analysis that combines damage features which are based on the relative change in amplitude of the LDV signals that are caused by both reflected and transmitted waves. In this study, the damage detection system is introduced and validated through field tests which were carried out at the Transportation Technology Center (TTC) in Pueblo, CO. In these tests, a rail car installed with the damage detection system traveled over a track that consisted of a discontinuity in the rail (i.e., welded joint) at different speeds up to 48 km/h (30mph). Results show that the proposed system can identify the rail segment in which the propagating waves on the rail head are affected by the presence of the welded joint.