Estimation of vertical bending stress in rails using train-mounted vertical track deflection measurement systems

Abstract

This paper presents a new methodology for the estimation of bending stresses over long sections of rails from the vertical track deflections measured using train-mounted instrumentation. The basis of this method is to apply mathematical correlations between the rail deflections and stresses to interpret the deflection measurements. A new finite element modeling method was developed to investigate mathematical correlations between the rail deflections and stresses for different ranges of track modulus. The stochastic nature of the track modulus, as one of the dominant factors influencing rail deflections and stresses, was simulated. The rail responses to applied loads were then calculated and compared for scenarios of constant and variable track modulus values. The study resulted in a detailed framework that can be employed to estimate rail bending stresses from train-mounted vertical track deflection measurements. This framework allows the estimation of the probability distributions of maximum tensile and compressive bending stresses in the rail head and base, which are necessary for calculating the rail reliability under applied loading.