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This paper studies the evolvement of the wear irregularity of contact wire using wire thickness data measured yearly from a section of railway catenary. The power spectral density and time-frequency representation based on the wavelet transform are employed for data analysis, with an emphasis on local wear irregularities that are crucial for contact wire condition assessment. To investigate the cause of wear irregularity evolvement and the mutual influence with the pantograph-catenary dynamic interaction, simulations considering the influence of wear irregularity are carried out based on the finite element method. Analyses of the actual wear irregularities and the dynamic contact force under singular and complex wear irregularities are performed. Although the wear irregularity has limited impact on the pantograph-catenary interaction, it can induce the vibration of pantograph and contact wire that will lead to a notable increase of contact force standard deviation. The evolvement of wear irregularity is closely associated with the span length and dropper distribution of catenary structure and the running direction of pantograph. In addition, it is found feasible to detect the wear irregularity based on contact force, on condition that the sampling frequency is high enough to reflect the indicative frequencies. [ABSTRACT FROM AUTHOR]

In this paper, we present a method for evaluating the performance of railway crossing rails after long-term service. The method includes 1) 3D profile and hardness measurements; 2) finite element simulation of wheel/rail interaction; and 3) numerical prediction of rail degradation. We conducted a case study on a crossing that had been in service for several years. The results indicate that the crossing experienced a run-in process in the major traffic direction, manifested as a widening of the running band, an enlargement of the contact patch size, a decrease in contact stress and eventually a reduction in plastic deformation and wear. However, the wheel/rail interaction was exacerbated in the minor traffic direction which induced more severe plastic deformation and wear. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) finite element (FE) dynamic frictional rolling contact model is presented for the study of short pitch corrugation that considers direct and instantaneous coupling between the contact mechanics and the structural dynamics in a vehicle-track system. In this study, we examine the system responses in terms of vibration modes, contact forces and the resulting wear with smooth rail and corrugated rail with progressively increasing amplitude to infer the conditions for consistent corrugation initiation and growth. Wear is assumed to be the damage mechanism, and short pitch corrugation is modeled using wavelengths from field observations of a Dutch railway. The contribution of this paper is a global perspective of the consistency conditions that govern the evolution of short pitch corrugation. The main insights are as follows: (1) the longitudinal vibration modes are probably dominant for short pitch corrugation initiation; (2) during short pitch corrugation evolution, the interaction and consistency between longitudinal and vertical modes should determine the development of short pitch corrugation, and once a certain severity is reached, vertical modes become dominant; and (3) in the case simulated in this paper, corrugation does not grow probably due to not only the different resulting main frequencies of the vertical and longitudinal contact forces, but also the inconsistency between the frequencies of the vertical and longitudinal vibration modes and the resulting wear. It is inferred that in the continuous process of initiation and growth of the corrugation, there should be a consistency between them, and this could be done by the control of certain track parameters. [ABSTRACT FROM AUTHOR]

This study evaluates the degradation of wheels and rails at railway crossings. The evaluation method is composed of 1) finite element simulation of dynamic wheel/crossing interaction and 2) multi-criteria analysis of wheel/rail degradation in terms of yield behavior, rolling contact fatigue (RCF) and wear. With the aid of this method, we conducted a case study identifying the proper yield strength of rail steel material for a 54E1-1:9 crossing under a specified traffic condition. The case study indicates that the wear of contact bodies is more sensitive to train speed compared with yield and RCF; the increase of rail yield strength suppresses rail degradation while exacerbating wheel degradation; and rail yield strength in the range of 500–600 MPa is preferred to achieve a good trade-off between the wheel and rail degradations. • A method is proposed to evaluate the degradation of wheels and rails at railway crossings. • The method uses finite element simulation and multi-criteria analysis. • Wheel/rail degradation is evaluated in terms of yield behavior, rolling contact fatigue (RCF) and wear. • A case study is conducted to identify the proper yield strength of rail steel material for a 54E1-1:9 crossing. [ABSTRACT FROM AUTHOR]

Squats are associated with high frequency vibrations of the wheel-rail system and can be registered using axle box acceleration (ABA) measurements. In this paper a three-dimensional finite-element (FE) model is proposed to capture the dynamic features of the ABA related to squats in the high frequency range. The FE model is validated relying on a set of real-life ABA measurements at two characteristic rail surface defects (light and severe squats), located in a section of the railway network in Assen. The Netherlands. The FE model managed to properly capture the dynamic features in the range of frequencies up to 2000 Hz. [ABSTRACT FROM AUTHOR]

• A methodology is proposed to study rail vibrations and control by fastening constraints. • Vibration modes of rail-fastening are identified by operating deflection shapes. • Waves of rail-fastening are measured by synchronized multiple-acceleration wavelet. • A 3D finite element model of rail-fastening is developed and validated. • Sensitivity analysis of fastening parameters provide insights into rail vibration control. This paper investigates three-dimensional (3D) rail vibrations under fastening constraint up to 5000 Hz and provides insights into rail vibration control by fastening parameters. A methodology is proposed, including experimental investigation and numerical simulations of rail vibrations. Three steps are considered: 1) experimental investigation of rail vibrations under fastening constraint; 2) validation and analysis of 3D finite element (FE) modeling of rail-fastening systems; 3) rail vibration control by fastening parameters. In Step 1, operating deflection shape (ODS) and synchronized multiple-acceleration wavelet (SMAW) measurements are applied to identify rail vibration modes and measure wave propagation characteristics under fastening constraint. In Step 2, a 3D FE model capable of reproducing the dynamic behaviors of rail-fastening up to 5000 Hz is developed to analyze rail vibrations and validated using measurements from Step 1. In Step 3, insights into the control of rail vibrations are gained by sensitivity analysis of fastening parameters using the validated 3D FE model from Step 2. The results indicate that (1) under fastening constraint, ODS measurement identifies vertical bending modes, longitudinal compression modes, and lateral bending modes of the rail with shifted frequencies and significantly reduced vibration amplitude compared to that of free rail. (2) Vertical wave attenuation of rail-fastening is relatively small between 1800 and 3600 Hz, and lateral wave attenuation presents a dominant peak at about 3800 Hz. (3) Compared to the vertical and lateral directions, the fastening system constrains the longitudinal rail vibrations less strongly. (4) The change of fastening stiffness and damping can control rail mode frequencies and their vibration amplitude, and influence the wave propagation velocities and attenuation along the rail. [ABSTRACT FROM AUTHOR]