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A study on transient wear behavior of new freight wheel profiles due to two points contact in curve negotiation

Shadfar M., Molatefi H.

Journal of Theoretical and Applied Mechanics

2017

Vol. 55 nr 2

621--634

Systematic examinations on wear behavior of stick/slip contact around metal on metal have shown that the dissipated energy and contact forces are two important parameters of wear of wheels and rails. Nevertheless, an accurate estimation of these parameters is still a great challenge. Recent developments of non-linear dynamical models and simulation of operational conditions have tried to find a solution of this challenge. These results are used as the input to calculations of wear propagation. Though, the dynamic model should be able to predict wheel-rail interaction with high accuracy. In addition, wheel-rail wear is a function of several other parameters whose their integrated influence becomes more than the main discussed ones. In this study, with the help of multi-body dynamics (MBD), an open wagon equipped with three pieces bogies, considering non-linear effects of friction wedges and structural clearances is modeled in Universal Mechanism. Tangent and curved sections of the track considering random vertical and lateral irregularities are simulated. The simulation results are used to calculate wear of both left and right wheels separately. Specht’s wear model based on Archard’s wear model is used. The studied parameters are the rail side coefficient of friction, track quality, track curvature, velocity and rail side wear. Finally, the effects of mentioned parameters are studied on wear depth and wear pattern of new wheel profiles under incompatible contact (which occurs in Iran railway network). The results show different wear volume and wear pattern compared to compatible contact.

On the investigation of wheel flange climb derailment mechanism and methods to control it

Molatefi H., Mazraeh A.

Journal of Theoretical and Applied Mechanics

2016

Vol. 54 nr 2

541--550

In this research, investigations are focused on the study of railway vehicle wheel flange climb derailment. A three dimensional nonlinear dynamic model of the wheel-set and suspension system is developed. Having validated the model through field tests, the effect of friction coefficient, wheel-set AOA, vehicle suspension system and running speed on the wheel flange climb derailment are investigated. In addition, different rail lubrication methods are studied and their effects on the wheel flange climb derailment are compared in the case of two point contact for nonlinear wheel-rail profiles. The results are debated and recommendations proposed to improve running safety against derailment.