Numerical Simulations to Examine the Interaction of Train-Induced Guided Waves With Transverse Cracks

Abstract

This paper presents the results of a numerical study aimed at investigating the propagation of guided waves generated by train wheels on rails. The particular application of interest is to exploit such waves for the identification of transverse cracks located in the rail head. The research presented is part of an ongoing project aimed at developing a non-contact damage detection system based on laser Doppler vibrometer measurements. In this study, numerical simulations were carried out using three rail models. The first two models consisted of a transverse crack whose size is 20% and 10% of the rail head cross-section (RHC), respectively. The third model consisted of the same crack size as the first model, but it was designed to be longer before and shorter after the location of the crack compared with the first model. The goal of this model was to examine the location where the effect of cracks on the waves first appeared. To acquire train-induced guided waves to use in the simulations, an accelerometer was placed under a rail head, and propagating waves were recorded during the passage of an operating train. Afterward, on each rail model, the location of excitation and two measurement points were shifted forward over the rail to replicate the movement of the defect detection system. Two damage functions were used to examine the change in wave propagation caused by cracks, while a multi-dimensional damage index consisting of the damage functions was used to identify the location of the crack (20% of RHC).