Axle burn-off and stack-up force analyses of a railroad roller bearing using the finite element method
Wang, Hao
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Permalink
https://hdl.handle.net/2142/23056
Description
Title
Axle burn-off and stack-up force analyses of a railroad roller bearing using the finite element method
Author(s)
Wang, Hao
Issue Date
1996
Doctoral Committee Chair(s)
Cusano, Cristino
Conry, Thomas F.
Department of Study
Mechanical Engineering
Discipline
Mechanical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Mechanical
Language
eng
Abstract
Railroad bearing-related failures are a primary concern to the railway industry. A bearing-related failure can cause derailment and result in millions of dollars in damage. The bearings used in railway applications are almost exclusively tapered roller bearings and are composed of a two-row assembly with a single element containing the outer race for both rows of rollers (the cup) and separate elements for the inner races (the cones). From a reliability standpoint, the bearing-axle assembly may be the most critical component on a rail car. A bearing under loose-cone conditions is prone to internal seizure which can result in an axle burn-off, one of the most detrimental of railroad failures.
To better understand the mechanism leading to the burn-off process, a thermomechanical analysis of a railroad axle with a tapered roller bearing assembly is conducted. For this analysis, it is assumed that the bearing elements have seized or fully jammed and the smallest resistance torque is due to the friction at the loose cone-axle interface. Temperature-dependent material properties are used as well as a coefficient of friction obtained by means of a pin-on-disk apparatus over a range of temperatures up to 1,000$\sp\circ$C. For initial radial clearances between the cone and axle varying from 0.05 to 5.0 mm and an initial ambient temperature of 25$\sp\circ$C, the thermomechanical degradation of the axle is examined as a function of time. The times required for plastic collapse of the axle to occur are determined for the various clearances. For the conditions considered, this collapse takes place in less than three minutes.
Stack-up forces of the same assembly are also examined. A parametric study was made using factors contributing to these stack-up forces. Steady-state normal and temperatures based on some common abnormal operating conditions seem to have very small effects on the stack-up forces, but a transient temperature due to a number of jammed rollers shows fast and detrimental effect on the stack-up system by causing a loose-cone condition.
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