Diffuse ultrasonic backscatter measurements for monitoring stress in rail

Abstract

Recent research in polycrystalline materials, both theoretically and experimentally, has demonstrated a dependence of diffuse ultrasonic backscatter (DUB) on applied stress. This dependence has been used to develop a measurement device for monitoring longitudinal stress in continuous welded rail (CWR). However when moving this research from the laboratory setting to field applications many additional challenges are encountered with respect to the experimental method. In this presentation, results from initial field experiments are presented. This work is performed on a switch track from a railroad mainline to a short line railroad siding. Comparison between DUB measurements and actual stress in the rail is accomplished through the use of four stress modules (based on standard strain gauge technology) that were installed at four different locations along test site. In these field tests, DUB experiments using two orthogonal shear waves are investigated. Procedures to mitigate errors in our experiments and techniques to refine the measurement for more accurate results are discussed. These field experiments highlight the utility of this approach with respect to practical and financial considerations for determining induced stresses in CWR. [Research supported by FRA.]