Development of a non-contact remote ultrasonic system for the non-destructive inspection of railroad tracks
(Funded by the National Science Foundation and "On-line high-speed rail defect detection" funded by the Department of Transportation/Federal Railroad Administration).
These projects are aimed at the development of a new-generation system for the nondestructive evaluation of railroad tracks in service. Two approaches are being examined, namely 1) a cross-sectional ultrasonic method and 2) a longitudinal (low-frequency) vibrational method. The first method employs non-contact laser and air-coupled ultrasonic sensors that do not require contact with the test piece. The second method exploits the acoustic waveguide nature of the rail geometry to provide long-range defect detection. The two methods are complementary to one another in terms of inspection speed and defect detection sensitivity. Our results show that the non-contact cross-sectional inspection can be performed at speeds comparable to those used today by conventional rail inspection methods. Besides non-contact testing, the added advantage is the possibility of inspecting the entire cross-section of the rail with fewer "blind spots" than allowed by conventional NDE of rails. The long-range inspection does not have speed limitations as the probing waves travel at the speed of sound. Current activities are aimed at characterizing reflection and transmission coefficients of various vibrating modes in the presence of transverse-type defects. The technologies are being tested in the field with the help of San Diego Trolley, Inc.
Some relevant publications:
Lanza di Scalea, F, Rizzo, P, Coccia, S, Bartoli, I, Fateh, M, Viola, E and Pascale, G, “Non-contact Ultrasonic Inspection of Rails and Signal Processing for Automatic Defect Detection and Classification,” Insight - Non-destructive Testing and Condition Monitoring, EURO Issue on NDT in the Rail Industry, 47(6), pp. 346-353, 2005.
Bartoli, I, Lanza di Scalea, F, Fateh, M and Viola, E, “Modeling Guided Wave Propagation with Application to the Long-range Defect Detection in Railroad Tracks,” Nondestructive Testing & Evaluation (NDT & E) International, 38(5), pp. 325-334, 2005.
Lanza di Scalea, F, Bartoli, I, Rizzo, P and McNamara, J, “On-line High-speed Rail Defect Detection,” Technical Report DOT/FRA/ORD-04/16, Department of Transportation/Federal Railroad Administration, 2004.
McNamara, J, Lanza di Scalea, F and Fateh, M, “Automatic Defect Classification in Long-range Ultrasonic Rail Inspection Using a Support Vector Machine-based Smart System,” Insight - Non-destructive Testing and Condition Monitoring, EURO Issue on NDT in the Rail Industry, 46(6), pp. 331-337, 2004.
McNamara, J and Lanza di Scalea, F, "Improvements in Non-contact Ultrasonic Testing of Rails by the Discrete Wavelet Transform," Materials Evaluation, 62(3), pp. 365-372, 2004.
Lanza di Scalea, F and McNamara, J, "Measuring High-frequency Waves Propagating in Railroad Tracks by Joint Time-Frequency Analysis," Journal of Sound and Vibration, 273(3), pp. 637-651, 2004.
Lanza di Scalea, F and McNamara, J, "Ultrasonic NDE of Railroad Tracks: Air-coupled Cross-sectional Inspection and Long-range Inspection," Insight - Non-destructive Testing and Condition Monitoring, EURO Issue on NDT in the Rail Industry, 45(6), pp. 394-401, 2003.
