Effect of Surface Hardening on Dynamic Frictional Rolling Contact Behavior and Degradation of Corrugated Rail

Yuan Gao,Yibin Liu,Jingmang Xu,Ping Wang

doi:10.1155/2019/5493182

Abstract

The present study was undertaken to evaluate the effect of surface hardening technology on dynamic frictional rolling contact behavior and degradation of corrugated rail in Shenzhen. Characteristic parameters such as length and depth of corrugation were analyzed by means of a continuous measurement method based on the corrugation analysis trolley. The explicit finite element method for material hardening characteristics and real contact geometry was adopted to set up the 3D transient FE model of wheel and rail, after which the value and distribution of stress/strain as well as contact solutions could be obtained during frictional contact, and then the Archard wear model and simplified wear superposition method are integrated as a numerical simulation tool for rail wear after hardening. The simulation results show that laminar plasma surface hardening technology can increase residual stress and shear stress in quenched zones, leading to local stress concentration at their boundaries; the plastic strain in the matrix material is higher than that in the quenched zones, while the strain concentration is mainly focused on the matrix material. The hardening can remarkably reduce the rail wear along the corrugation wave, and the wear depth of material with hardening technology is about 36% of that of nonhardening material. Laminar plasma surface hardening technology can therefore restrain the development of rail corrugation.

Highlights

Since Shenzhen Metro Line 11 went into operation, shortwavelength corrugation has been discovered on the surface of metro rails after two years in service
The plastic deformation resistance of its matrix material is lower than the quenched zone, so the plastic strain of the matrix region is relative higher, while the von Mises stress in the quenched zone is lower than the yield strength, meaning no plastic deformation occurs in this area. is shows that plastic deformation primarily occurs in the matrix region, which is relatively soft compared to hardening regions. e equivalent stress peak mainly acts on the quenched zone
By effectively combining the transient rolling contact FE model and the Archard wear model as well as the simplified superimposition method, the longitudinal distribution of corrugated rail wear (Figure 20) can be calculated. e maximum rail wear loss does not appear at the crest, the wear peak lies between the crests of rail corrugation, with a phase difference between rail wear and geometric fluctuations in rail corrugation. e wear loss curve of the nonhardened corrugated rail is relatively smooth, and its value is greater than the hardened corrugated rail

Summary

Introduction

Since Shenzhen Metro Line 11 went into operation, shortwavelength corrugation has been discovered on the surface of metro rails after two years in service. Jin et al [9] used the numerical tool hunting for the effect of sleeper pitch on the rail corrugation initiation and development at tangent track, considering the combination of Kalker’s rolling contact theory, linear frictional work model, and dynamic model of a vehicle coupled with the tangent track, and the excited resonant frequencies of wheelset and track were calculated in detail at different running speeds. In order to prevent the development of corrugation, various models are established to analyze the dynamic behavior of interaction between wheel and corrugated rail, and many methods have been put forward to prolong the service life of rail, which have resulted in surface hardening technique being gradually applied in the railway industry. According to the characteristics of a hardened rail, it is important to research the effects of surface hardening on stress/strain distribution regularities of rail and axle box vibrations using an explicit finite element model (FE model). e transient frictional rolling contact solutions, axle box acceleration, and the stress/strain during impact are investigated. is should help reveal the inhibitory action of the laminar plasma hardening technique on the development of rail corrugation so as to provide theoretical support for its application to metro rail processing

Simulation and Experimental Procedure

Transition layer 4

50 Dynamic relaxation region

Degradation of Rail with Wave Corrugation

Phase difference

Conclusion