Vibration Nondestructive Testing of Continuous Welded Rails: A Finite Element Analysis

This paper presents a finite element model for the dynamic vibration of continuous-welded rails (CWR) under different longitudinal stresses and base conditions. The model supports the physical principles of a vibration-based nondestructive testing (NDT) technique aimed at inferring the lateral and vertical strength, and the neutral temperature of CWR. The model consists of a ~ 5 meters-long rail periodically restrained by distributed translational springs that simulates the lateral and vertical resistance provided by baseplates, fasteners and spikes. Vibration is triggered by a force function equivalent to the mechanical impact of a hammer. The frequency content of the vibrations below 700 Hz and across a range of different longitudinal stress and support conditions is computed using the power spectral density, which constitutes the input matrix of a machine learning algorithm able to learn the complex relationship among frequencies, axial stress, and support conditions. Finally, the model is used to quantify any differences in excitation and detection points to optimize the setup of the proposed NDT technique.