Detection of Transverse Defect in a Railhead Based on Guided Waves Generated by Radiation Laser

Abstract

The main cause of train derailment is related to transverse defects that arise in the railhead. These consist typically of opened or internal flaws that develop generally in a plane which is orthogonal to the rail direction. Ultrasounds based testing is performed according to the excitation-echo procedure. It is conducted conventionally by using a contactless system using a laser as excitation and air-coupled acoustic sensors for wave reception. The objective of this work is to study theoretically an integrated system for rail diagnosis which is based on guided waves and which does not necessitate any contact with the rail. On the opposite of the existing inspection devices, this paper proposes a laser vibrometry rotational perform the reception of the echoes. Complete modeling of the rail has been performed after that by using the three-dimensional equations of thermoelasticity and the solution in terms of displacements has been calculated by using the finite element method. The study has dealt with a special device configuration for the generation of waves by laser excitation and the detection of echoes by using laser vibrometry.