Dr Philip W. Loveday is a Principal Researcher at the Council for Scientific and Industrial Research (CSIR) in South Africa. He has been involved in R&D of piezoelectric devices for the past twenty years and is the leader of a small research group involved in piezoelectric actuators and motors and guided wave ultrasound. In 1997 he was responsible for the experimental development of piezoelectric ultrasonic transducers for permanent installation on railway lines as part of a rail - break detection system. Over 1500 of these transducers have been produced. More recently, his research has focussed on numerical modelling and measurement techniques for guided waves in rails. The numerical techniques combine semi-analytical finite element models of the rail with conventional three-dimensional piezoelectric finite element models. The measurement techniques are used to extract the individual modes of propagation from scanning laser vibrometer measurements. These techniques are currently being applied to develop improved guided wave transducers for monitoring larger distances at lower cost per kilometre.

Abstract

Guided Wave Inspection and Monitoring of Railway Track

Cost-effective NDE of the vast length of ageing railway track around the world remains challenge for the community. Since continuously welded railway lines may be thought of as one-dimensional elastic waveguides, they are natural candidates for guided wave ultrasound, which offers the potential to interrogate a large length of rail from a single position.

This presentation will review some of the efforts made to apply guided wave ultrasound to rails and the different approaches employed. These approaches vary from stationary transducer arrays, train or vehicle borne inspection systems, used in pulse echo mode, systems detecting train generated noise and systems employing permanently attached transducers in transmission mode.

While the approaches employed differ, they posses a common physics basis of guided wave propagation, transduction and interaction with damage. Features of modelling and measurement techniques applied to rails, will be presented. Finally, some of the current practical challenges hindering adoption of this technology will be discussed.