Numerical modelling of defects in rails

Abstract

The semi-analytical finite element (SAFE) method has become a popular tool for the analysis of elastic waveguides with complex cross-sections. We employ a recently developed hybrid SAFE-3D FE method to study the scattering of guided waves at discontinuities such as welds or cracks in continuous welded train rails. The aim of this particular study is to determine if it is possible to distinguish between scattering from welds and cracks for a given incident mode which is known to propagate long distance in rails. This study represents an initial step in the extension of the current ultrasonic broken rail detector (UBRD) system to detect cracks before complete breaks occur, which will require distinguishing between reflections from cracks and other reflectors such as welds, in order to avoid false alarms. Characterisation of transmission through welds is also useful for predicting the long-range attenuation of transducers in non-destructive evaluation (NDE) and monitoring systems, such as UBRD system developed by the Institute for Maritime Technology (IMT) and the Council for Scientific and Industrial Research (CSIR).