Wheel-Rail Contact Wear, Work, and Lateral Force for Zero Angle of Attack—A Laboratory Study

Abstract

Most of the wear indices, used in the railroad industry for predicting wheel/rail wear, are functions of angle of attack between wheel and rail. Further, the wear problem has been studied in terms of wear coefficients which relate the wear volume to the work done in the wear process. The wear-work principle, as applicable to wear indices and coefficients, is enunciated and its implications are discussed. An analysis of the wheel/rail interaction as a two point contact problem is presented. To establish the validity of the theory and applicability of the indices, results from a series of four experiments on a quarter scale laboratory rig are reported. The experiments are with “zero angle of attack” and an externally applied lateral load on the wheel, representing the idealized operation of a perfect radial truck. It is observed that contrary to the prediction, based on most of the suggested indices, there is noticeable wear of both wheel and rail even under zero angle of attack. It is concluded that lateral forces should be explicitly included in wear index formulation. Calculated values of wear coefficients, in the range 7.7E-5 to 38.0E-5 for the case of total contact slip and 21.6E-5 to 120.8E-5 for the case of adhesive or micro slip, indicate the effect of plastic flow in the contact when the Holm-Archard relation is assumed valid. Approximate validity of the Derby wear index, based on energy considerations, indicates that indices which are primarily functions of angle of attach are not quite valid for predicting field wheel/rail wear. It is also concluded that the wear-work principle as formulated in the paper can be considered to be reasonably valid.