Researchers in the University of Warwick’s Department of Physics have developed a novel non-contact method of using ultrasound to detect and measure cracks and flaws in rail track – particularly gauge corner cracking - that has the potential to simply be attached to a normal passenger or freight train travelling at high speeds.
Current ultrasonic techniques for detecting defects only work at much slower speeds (around 20-30 miles an hour). A handful of special trains have been created using conventional contacting ultrasonic techniques but there are severe limitations as to when and where they can be used without disrupting the network. The new technology, developed by Dr Steve Dixon, Dr Rachel Edwards and Mr John Reed at the University of Warwick, makes use of a particular form of ultrasonics – a “low frequency wide band Rayleigh wave” to produce a crack testing technique that works at high speed and could transform every train in the country into part of a 24 hour network of rail crack detectors.
The researchers have taken pairs of “electromagnetic acoustic transducers” (EMATS) which generate and detect the “low frequency wide band Rayleigh wave” on the rail without touching the rail. This Rayleigh wave travels along the surface of the rail head, along the length of the rail, penetrating down to a depth of several millimetres. They simultaneously use a wide range of frequencies within a single Rayleigh wave pulse (hence their description of it as a “wide band Rayleigh Wave”) as different frequencies allow penetration of the rail to a range of precise measurable depths.
Peter Dunn | alfa
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