The concept of the rail damage function provides vital understanding of the operational performance of rail grades in terms of surface degradation. Previously, material specific damage functions have been derived from measurements in track combined with vehicle-track simulations. However, from the occurring wide range in track loading conditions it is difficult to achieve clear characterization results from track data only. To reach more controlled loading conditions, a rollingsliding two-disc laboratory set up could be applied. The validation of a two-disc test approach in order to define rail/wheel interface wear and RCF response is the topic of the here proposed study.@en

The acting forces and resulting material degradation at the running surfaces of wheels and rail are determined by vehicle, track, interface and operational characteristics. To effectively manage the experienced wear, plastic deformation and crack development at wheels and rail, the interaction between vehicle and track demands a system approach both in maintenance and in design. This requires insight into the impact of train operational parameters on rail- and wheel degradation, in particular at switches and crossings due to the complex dynamic behaviour of a railway vehicle at a turnout. A parametric study was carried out by means of vehicle-track simulations within the VAMPIRE® multibody simulation software, performing a sensitivity analysis regarding operational factors and their impact on expected switch panel wear loading. Additionally, theoretical concepts were cross-checked with operational practices by means of a case study in response to a dramatic change in lateral rail wear development at specific switches in Dutch track. Data from train operation, track maintenance and track inspection were analysed, providing further insight into the operational dependencies. From the simulations performed in this study, it was found that switch rail lateral wear loading at the diverging route of a 1:9 type turnout is significantly influenced by the level of wheel–rail friction and to a lesser extent by the direction of travel (facing or trailing). The influence of other investigated parameters, being vehicle speed, traction, gauge widening and track layout is found to be small. Findings from the case study further confirm the simulation outcome. This research clearly demonstrates the contribution flange lubrication can have in preventing abnormal lateral wear at locations where the wheel–rail interface is heavily loaded.

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This work investigates the power dissipation in a wheel/rail system through friction work modeling. In order to identify the effect of the friction coefficient on the power dissipation in the wheel/rail contact, several simulations were performed using a three-dimensional multibody model of a railway vehicle implemented in the software package VI-Rail Adams. The power dissipation and wear rates of the inner and outer wheels of the first bogie of the vehicle running over a curve of a metro line were calculated for different friction coefficients varying from 0.2 to 0.7. The total frictional work was obtained from the resultant force and slip in a reference point. The wear was also analyzed according to the Tγ method including the spin, in combination with Kalker׳s simplified theory Fastsim, assuming that the wear is proportional to the frictional work. Two sets of rail and wheel profiles were studied in order to determine the effect of the profile׳s quality on the power dissipation and wear rates. To this end simulations and power calculations were performed with a friction coefficient of 0.4.

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When a train runs through a turnout or a sharp curve, high lateral forces occur between the wheels and rails. These lateral forces increase when the couplers between the wagons are loaded in compression, i.e., a rear locomotive pushing a train or a front locomotive braking a train. This study quantifies these effects for a train that begins braking when steadily curving and for a train that brakes upon entering a turnout. Our approach allows distinguishing between the effects of braking and the transient effects of entering the turnout. The dynamic derailment quotient is mapped as a function of the vehicle speed and the braking effort. Then the dynamic derailment coefficient obtained from the dynamic simulations is compared to results from quasi statics. This allows determining a dynamic multiplication coefficient that can be used on the quasi static derailment coefficient to obtain a first estimate of the dynamic derailment coefficient.

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Though numerical models based on multi-body dynamics (MBD) are often used to simulate the vehicle-track interaction at crossing impact, their relative capabilities and accuracy were not discussed. This paper aims to investigate the influence of wheelset flexibility on the result of crossing impact simulation in the frequency range 0–500 Hz. Two models are used: a MBD model with rigid wheelset and a reference finite element model that could fully account for the structural flexibility. Results of the two models as well as in-situ measurement show three characteristic frequencies of the vehicle-track interaction system induced by crossing impact. Based on the characteristic frequencies, the MBD model is tuned to resemble the reference FE model in terms of track and contact representation through a parametric analysis so that the influence of these differences can be isolated. It is found that the major influence of the wheelset flexibility is on the second characteristic frequency of the system, reflecting the second order bending of the wheelset. @en

One of the major costs incurred by railway companies is the maintenance of turnouts.This situation occurs because the large dynamic forces between the wheels of a train and the rails of a turnout cause excessive wear, rolling contact fatigue and rapid degradation of other components. A thorough understanding of the dynamic interaction between a train and a turnout could lead to a better design of the corresponding vehicle/track or of the damage mechanisms and subsequently to a smarter maintenance planning. Such an insight can be obtained through a detailed model of the train-turnout interaction. Such models exist in the literature for vehicle-track interaction, but they have some shortcomings when it comes to train-turnout interaction. This leads to the following research questions: 1. How to model the wheel rail contact? In this thesis different models are presented for the search of the contact location as well as for the normal and the tangential contact problem. Especially the relation between the contact models and vehicle dynamic simulation is investigated. 2. How to model the interaction between the wagons of the train? A quasi static approach has been presented and the results have been compared to results obtained through dynamic simulation. The analysis of the contact models in this dissertation will help researchers choose between the different contact models and their interaction with vehicle dynamic software. This should enable researchers to accurately model the contact in turnouts so that the deterioration mechanisms in turnouts can be understood. In turn, this understanding should lead to better maintenance and associated cost savings.@en