A TECHNIQUE for faster ultrasonic inspection of rails using low-frequency Rayleigh waves was described in a paper presented to the Railway Engineering conference in London on July 6 (p61).
University of Warwick physicists Dr Steve Dixon, Dr Rachel Edwards and John Reed are generating the wide-band Rayleigh waves using pairs of electromagnetic transducers which do not come into contact with the rails, permitting inspection at higher speeds than can be achieved using conventional methods. The different frequencies penetrate the rail head to varying depths, and the signal losses and reflections are analysed to locate and measure cracks in the rail.
Some experimental results have suggested that stress-induced changes in the steel microstructure may be detectable, which would offer the possibility of identifying rails which are likely to fail.
Testing with a greater range of rails is planned, and Dr Dixon anticipates that with further funding transducers could be developed for mounting on trains in normal service, providing frequent inspection data without disrupting traffic.
University of Warwick, UK
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