Laser Ultrasonics Inspection of Train Wheel - Evaluation of Optimized Setup

Abstract

In the railway field, the safety of passengers and the service life of train components are a crucial issue. For this reason, continuous periodic inspections by non-destructive techniques are required. Among these, ultrasonic tests are widely used in this field, even though the conventional ultrasound techniques have the disadvantage of requiring the disassembly of the wheels and of putting the train out of service. This procedure is expensive and time-consuming and can be neglected if non-contact ultrasonic techniques are used. In this work, the authors present an experimental research on some defects, artificially obtained on a railway wheel supplied by Trenitalia Spa, by adopting three different experimental setups and comparing the results. The proposed method uses laser equipment in generation and reception of the ultrasonic waves. The receiving unit combines a continuous wave laser and an interferometer in order to detect the surface displacements. In addition, when used in service conditions, the receiving by the interferometer is facilitated, because the tread of the wheel is very reflective (thanks to wheel – rail contact). The research aims at optimizing the experimental setup through a number of measurements carried out by varying some experimental parameters to evaluate the robustness and reliability of the technique.