Detection of Missing Rail Fasteners Using Train-Induced Ultrasonic Guided Waves: A Numerical Study

This study presents the results of the numerical study that aims to identify the missing fastener along the rail using train-induced guided waves. This study is part of an ongoing project that intends to develop a non-contact damage detection system based on the measurements obtained from a laser Doppler vibrometer placed on a moving platform. To achieve the goal, (i) modal analysis was conducted to determine the frequency range of interest in which the dynamic response of the rail is sensitive to the missing fastener (i.e., the frequency range in which the waves localize at the rail foot), (ii) a three-dimensional finite element method (FEM) simulation was conducted to imitate the movement of the wheel excitation and the measurements. The goal of the FEM model is to examine the effect of the missing fasteners on the dynamic response of the rail in the frequency range of interest. The guided waves recorded from a rail through an accelerometer during the passage of an operating train were used as the excitation signal in the FEM simulation. A damage function was introduced to examine the change in the wave energy caused by the missing fastener. Consequently, the location of the missing fastener was identified.