In situ control of hidden parts of rails - numerical experiments
Résumé
Rail control is an important safety concern for railway infrastructure maintenance. To achieve rail in situ control, only rail upper part (rail head) is easily accessible to instrumentation. The present work assesses the feasibility of controlling the whole lower part of rail (rail foot) using ultrasound when inspecting from its upper part. The absence of direct wave path between the transducer and the defect implies that only multiple-reflected waves are measured. The underlying complexity of the signal is dealt with the topological imaging framework. 2D numerical experiments are performed in order to simulate the experimental signals that are processed according to the method. The simulated defects correspond to three existing rail defects: longitudinal vertical crack, corrosion-induced material removal and rail foot damage. For such defects, classical ultrasonic techniques are rather inefficient. It is shown that detection and location of these hidden defects can be achieved from rail head, using the proposed methodology.