In the UK, changing usage patterns for the rail network mean that rolling contact fatigue (RCF) in the railhead is an increasingly urgent problem. Current ultrasonic testing techniques have limitations in terms of testing speed and ability to reliably detect such defects. A different approach to the problem is to use ultrasonic surface waves generated and detected in a pitch-catch manner, thus simplifying the probe to detect surface defects such as RCF and to ignore deeper bulk defects. By using a pitch-catch configuration several of the speed limitations are removed; the probes are free to move as soon as each signal has been generated, without the need to wait for detection of the signal, and separation of the probes can be increased to allow for limited pulse repetition rates. Better reliability of detection for surface defects is also found, with the transmitted signal being dominated by the deepest surface-breaking defect present between the probes. We present details of a new high speed system, consisting of several electro-magnetic acoustic transducers (EMATs) to generate and detect the signals, with a high speed A-D system which has the ability to detect, window and FFT time signals and analyse the FFT to give a cut-off frequency within 1 ms, giving a depth for any defects present between the probes.


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    Title :

    High speed detection and characterization of defects in the railhead


    Additional title:

    Hochgeschwindigkeitsnachweis und Charakterisierung von Fehlern in Schienenköpfen


    Contributors:
    Edwards, R.S. (author) / Fan, Y. (author) / Dixon, S. (author)


    Publication date :

    2007


    Size :

    7 Seiten, 4 Bilder, 20 Quellen





    Type of media :

    Conference paper


    Type of material :

    Storage medium


    Language :

    English




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