Application of a semianalytical strain assessment and multiaxial fatigue analysis to compare rolling contact fatigue in twin‐disk and full‐scale wheel/rail contact conditions

Nicola Zani,Magnus Ekh,Anders Ekberg,Angelo Mazzù

doi:10.1111/ffe.13595

Abstract

AbstractA semianalytical model is introduced to assess rolling contact fatigue problems in railway applications. The constitutive law is based on the nonlinear kinematic and isotropic hardening model of Chaboche–Lemaitre, which allows the cyclic elastoplastic strain under the contact surface to be evaluated. The much higher computational effectiveness in comparison with finite element (FE) analyses is quantified. The Dang Van multiaxial fatigue criterion is implemented to evaluate the rolling contact fatigue in the subsurface elastic region where cracking is relatively rare but more dangerous than surface cracks. The influence of the presence of sulfides in the wheel matrix in decreasing fatigue strength is also assessed by means of Murakami's approach. The model is used to compare conditions under small‐scale twin‐disk experiments to full‐scale wheel/rail contact conditions. It is found that, for the same Hertzian pressure, the small‐scale contact is more conservative in that it causes a deeper plasticized layer as compared with the elliptical full‐scale contact. In the investigated cases, crack initiation is also not expected according to Dang Van criterion in neither of the studied contact conditions.

Highlights

The trend towards heavier axle loads for freight transport and higher speed passenger trains has increased demands on the design of railway components
For the full-scale problem, we considered a wheel with a diameter of 900 mm and a rail with a transverse curvature radius of 600 mm
The nonlinear kinematic and isotropic hardening model of Chaboche–Lemaitre was applied to cyclic contact problems

Summary

| INTRODUCTION

The trend towards heavier axle loads for freight transport and higher speed passenger trains has increased demands on the design of railway components (e.g., wheels and rails). It should be pointed out that the main weak point of this solver based on an analytical solution of the contact pressure is that it cannot consider the residual stress because after the loading cycle, the stress is always zero, which is valid only in the case where the material does not plasticize. The conclusion is that the coded model can predict the dominating strain component in the rolling contact problem with good accuracy

| RESULTS

Findings

| CONCLUSIONS