Dynamic characterisation of the wheel/rail contact using ultrasonic reflectometry

This work investigates the use of a rail mounted ultrasonic array to measure the contact conditions between the train wheel and rail and move towards making dynamic measurements. As an ultrasonic wave strikes and interface, it is partially transmitted depending on the contact condition. At areas of high stress, a significant amount of the wave is transferred thus resulting in reduction in amplitude of the reflected signal. Previous work has successfully characterised the wheel/rail contact using a 2-dimensional scanning approach with a focusing transducer. This process, although highly accurate, is time consuming and confined to the laboratory. An ultrasonic array is used to characterize the interface and comparisons are made between the two methods. A pilot study was then carried out using a rolling ball to develop a methodology for dynamic measurements. Work is now underway to transfer this to carry out full-scale wheel/rail rig dynamic measurements.