Investigation of Wheel and Rail Rolling Contact Fatigue Using a Full-Scale Simulator

Tournay, Harry; Shu, Xinggao; Keylin, Alexander; Cakdi, Sabri · 2022 · ROSA P / United States. Department of Transportation. Federal Railroad Administration

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Summary

This report details the development and initial testing of a full-scale Rolling Contact Fatigue Simulator (RCFS) by Transportation Technology Center Inc. (TTCI), funded by the Federal Railroad Administration (FRA). The research addresses the root causes of wheel and rail surface damage, specifically high-impact wheels (HIW) and rail spalling, which drive significant maintenance costs and safety concerns in North American railroads. The study aims to determine the limits of steering tractions on the low rail that initiate this damage, thereby establishing performance limits for bogies in heavy-haul operations. The methodology combined experimental testing on the RCFS with analytical contact stress modeling. The RCFS simulates a full-scale wheelset rolling on reciprocating rails, capable of applying nominal axle loads up to 49.5 tons and controlling steering forces via angle-of-attack and lateral displacement. Exploratory tests were conducted under 36-ton axle loads using Class C wheels and intermediate-strength rails under dry contact conditions. Traction-to-normal force ratios (T/N) of 0.1, 0.2, 0.3, and 0.4 were applied to quantify damage initiation. Analytical models using CONTACT software and finite element analysis (FEA) validated the experimental results by predicting subsurface von Mises stresses and plastic deformation based on field-measured forces from instrumented wheelsets. Key findings identified distinct damage regimes based on T/N ratios. Surface pitting initiated rapidly between 10,000 and 20,000 cycles at T/N ratios between 0.1 and 0.2, reaching a steady state thereafter. Critical damage, characterized by light spalling, occurred in the T/N range of approximately 0.15 to 0.3. Above T/N ≈ 0.3, an abrasive wear regime dominated, wearing away the pitting as it formed. Modeling confirmed that typical low-rail tangential forces on unlubricated tracks (T/N ≥ 0.1) cause permanent surface deformation in Class C wheels and intermediate-strength rails. Subsurface stresses reached approximately 106 ksi, exceeding the yield strength of Class C wheels. The study also noted that dry-contact tests failed to replicate the seasonal prevalence of HIW in winter, suggesting that hydraulic pressure from third-body layers like snow may be necessary to propagate cracks from pits. The significance of this work lies in establishing empirical limits for steering tractions to mitigate RCF. The results indicate that controlling low-rail steering tractions below specific thresholds can prevent the initiation of HIW and associated rail damage. The validated RCFS provides a platform for future research into refined T/N intervals, the effects of lubricants and third-body layers, and the development of improved freight car trucks. These findings support the creation of effective wheel/rail interface management strategies to reduce safety risks and financial burdens for the rail industry.

Key finding

Surface pitting damage initiates between traction-to-normal force ratios of 0.1 and 0.2, while abrasive wear regimes dominate above 0.3, with contact stress modeling confirming that typical low-rail tangential forces cause permanent surface deformation at T/N ratios as low as 0.1.

Methodology

simulator

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• road surface friction