We recently presented measurements of defects on the railhead, using a novel pitchcatch ultrasonic system comprising of two electro-magnetic acoustic transducers (EMATs) generating and detecting Rayleigh waves. Current systems used on the UK rail network for detecting surface breaking defects are limited in speed (< 30 mph) and accuracy (depths > 5 mm). The non-contact EMAT system has the potential to operate at higher line speed, improving network inspection coverage. The current system detects signals and performs an FFT in less than 1 ms, and changes in the detected signal amplitude and frequency content are used to characterise defects. A new set of simulated defects on sections of rail have been produced, including half-face slots machined normal to the railhead surface, clusters of angled slots, and pocket defects more typical of real defects. The smallest pocket defects are difficult to detect, with changes in signal amplitude and cut-off falling close to the noise level. However, at chosen higher frequencies a drop in FFT magnitude indicates the presence of a defect, and this indicator can be logically combined with amplitude and cut-off measurements to provide a more reliable result. Preparation for testing on a rotating rail rig at high speeds is ongoing.


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    Title :

    Ultrasonic detection of surface-breaking railhead defects


    Additional title:

    Nachweis von Oberflächenrissen in Schienenköpfen mittels Ultraschall


    Contributors:
    Edwards, R.S. (author) / Fan, Y. (author) / Papaelias, M. (author) / Dixon, S. (author) / Davis, C.L. (author) / Roberts, C. (author)


    Publication date :

    2008


    Size :

    8 Seiten, 7 Bilder, 18 Quellen





    Type of media :

    Conference paper


    Type of material :

    Storage medium


    Language :

    English




    Ultrasonic detection of surface-breaking railhead defects

    Edwards, R.S. / Holmes, C. / Fan, Y. et al. | Tema Archive | 2008


    Characterisation of defects in the railhead using ultrasonic surface waves

    Edwards, R.S. / Dixon, S. / Jian, X. | Tema Archive | 2006


    High speed detection and characterization of defects in the railhead

    Edwards, R.S. / Fan, Y. / Dixon, S. | Tema Archive | 2007


    Requirements for Transverse Railhead Profile and Railhead Roughness Following Grinding

    Grassie, S. L. / International Heavy Haul Association | British Library Conference Proceedings | 1997


    National Railhead

    Graham, V. | British Library Online Contents | 1997