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A new two-dimensional model of rolling–sliding contact creep curves for a range of lubrication types

Experimentally determined creep curves for rolling–sliding contact in lubricated conditions are found to deviate greatly from the standard theory for two-body contact. This article presents a new model to represent coefficient of adhesion (also known as traction coefficient) and creep based on experimental data gathered for a range of railway rail–wheel contact conditions. The model developed is based on a two-dimensional elastic foundation representation of a twin disc contact. This is used to quantify the creep curves in a similar manner to existing models of three-dimensional real rail–wheel contacts undergoing partial slip for a range of lubrication conditions. The work focuses on very low levels of creep, ranging from 0 to 1%, and lubricants experienced by a rail–wheel contact in service (dry, wet, flange lubricant). Lubricants used during the simulation of low adhesion conditions for driver training (soap and water, lignin and water) are also represented. The motivation for the research is inclusion of creep-traction characteristics in an on-board system being developed for prediction of low adhesion conditions at the rail–wheel interface based upon monitoring running conditions prior to brake application.