Technical Reports

Study of Friction and Creep Between Steel Wheels and Rails

  • 01
  • Jul
  • 1976
AUTHOR: C. Sciammarella, M. Press, S. Kumar, B. Seth, S. Nailescu, S. Kalpakjian
OFFICE: RPD
REPORT NUMBER: FRA/OR&D-76/271
SUBJECT: Track/Train Interactions
KEYWORDS: Adhesion, Traction, Contact Zone
ABSTRACT: A systematic experimental, parametric and similitude investigation of the friction and creep behavior of a steel wheel rolling on a steel rail is given. Laboratory investigation was performed on the l/5th scale experimental GM-IIT Wheel Rail Simulation Testing Facility reported on earlier. Investigation of the size and area of contact between the two wheels at different stages of surface wear shows that the initially elliptical (near Hertzian) area of contact changes fast into a near rectangular shape with a several-fold increase, depending on the load and the duration of testing and wear. It was found that Kalkers Theory fits the nondimensionalized data well, when wheel surfaces are near perfectly smooth. The product of actual contact area and creep is always constant for a given normal load and friction coefficient regardless of the surface roughness and wear time ( < 5 hrs.). This constancy law was derived on the basis of experimental data. It has been shown here that for the elastic and smooth surfaces the Carter-Poritsky theory also predicts the product of creep and theoretical area of contact as constant for a given load and operating friction coefficient. Generalized expressions for the interrelationship of friction coefficient, creep, actual- area of contact, normal load and shear modulus have been established on the basis of experimental data. Recommendations for future design improvements have been made on the basis of these relations.
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