Ultrasonic waves are routinely used in the railway industry to supply information about integrity of wheels, rails, and axles for both quality control assessment (during the production process) and ‘in situ’ when the rolling stock has to be periodically checked for maintenance purposes. Nevertheless, recently the authors proposed a different application of this technique which, although employing the same kind of equipment as a standard NDE control, is able to investigate the main features of the wheel-rail contact interface such as nominal contact area, real contact area, and contact pressure distribution. On the grounds of the promising results obtained in the previous tests, this study proposes a further practical approach to common problems of wheel-rail contact that possibly affect the regular development of railway operations. To this end, a number of wheel-rail systems were altered by artificially producing several kind of defects on their surfaces and thus obtained couplings were then analysed by the ultrasonic method in order to assess the capability of the technique to faithfully reproduce the modification introduced in the contact patch. The results of the experimental tests allow us to state that the ultrasonic analysis of wheel-rail contact interfaces can be effectively employed to detect any sort of irregularities potentially present due to normal operations, and foresees a future application of the method as a tool to monitor critical points of a railway line in order to ensure significant improvements in safety conditions.
Optimising Frequency-Based Railway Services with a Limited Fleet Endowment: An Energy-Efficient Perspective
