The rolling stock in railway freight transport has traditionally been mainly characterised by lowcost, long lifetime of the fleet, and relatively low requirements on running behaviour. However, the sector inEurope has acknowledged that in order to be competitive there is a need to develop more advanced wagons thatenable to maximise payload and speed in different scenarios, while reducing the overall system costs, includingwheelset and track deterioration. In the Shift2Rail project FR8RAIL, a consortium of wagon manufacturers,wheelset manufacturers, and research centres has worked to develop a new generation of the widely used robustY25 freight running gear, that minimises maintenance costs both on the vehicle and the track by improving thecurving performance and hunting stability. The dynamic behaviour of the proposed solutions has been studiedwith simulations-based EN14363 tests up to 30 tons/axle, and their expected impact on wheel wear and fatiguehas also been predicted, with satisfactory results regarding both damage modes.

This paper addresses the control design for automatic train operation of high-speed trains with protection constraints. A new resilient nonlinear gain-based feedback control approach is proposed, which is capable of guaranteeing, under some proper non-restrictive initial conditions, the protection constraints control raised by the distance-to-go (moving authority) curve and automatic train protection in practice. A new hyperbolic tangent function-based model is presented to mimic the whole operation process of high-speed trains. The proposed feedback control methods are easily implementable and computationally inexpensive because the presence of only two feedback gains guarantee satisfactory tracking performance and closed-loop stability, no adaptations of unknown parameters, function approximation of unknown nonlinearities, and attenuation of external disturbances in the proposed control strategies. Finally, rigorous proofs and comparative simulation results are given to demonstrate the effectiveness of the proposed approaches.

With the need for increasing length of freight trains, Longitudinal Train Dynamics (LTD) and its influence on the running safety becomes a key issue. LTD is a complex issue with contributions from both the vehicles and the operating conditions such as infrastructure design, braking regimes, etc. Standards such as the UIC Code 530-2 and EN-15839 detail the procedure for on-track propelling tests that should be conducted to determine the running safety of a single wagon. Also, it only considers a single S-curve and specifies neighbouring wagons and buffers. The resulting LTD would hence not be able to judge the effects of various heterogeneities in the train formation such as the adjacent wagons, buffer types, carbody torsional stiffnesses, curvatures, etc. Here, there is a potential of using three-dimensional multi-body simulations to develop a methodology to judge the running safety of a train with regards to its longitudinal dynamic behaviour, subjected to various heterogeneities. A tool based on three-dimensional multi-body simulations has been developed to provide Longitudinal Compressive Force (LCF) limits, tolerable LCF for wagon combinations passing through S-curves of varying curvatures and assess the sensitivities of the various heterogeneities present in the train. The methodology is applied to open wagons of the ‘Falns’ type on tight S-curves by calculating the corresponding tolerable LCF and the effect of various parameters on the same is discussed.

The number of operating high-speed trains in China is around 2800 today and 179,200 wheels are under maintenance in one reprofiling period. To help researchers to understand the evolution of the wheel profile and improve the reprofiling strategy of the wheels, this study predicts the development of wheel profiles on a high-speed train as function of mileage and compare simulated worn wheel profiles with measured ones. The methodology includes transient multi-body dynamic simulation, wheel-rail contact calculation and wear calculation with Archard's model. Calibrated by analysing measurements of worn S1002CN profiles and performing parameters sensitivity study in the wear model, the model is then used to predict the development of a recently designed wheel profile, called S1002CN-RF. The simulation results for S1002CN and S1002CN-RF show that the predicted wheel profiles coincide with the measured ones. Wear prediction of another high-speed wheel profile (LMA) validates that the vehicle performance with respect to wear could be further improved compared to using S1002CN or S1002CN-RF. Finally, the influence of track alignment and operating speed is investigated. The wear increases with the speed increasing up to 300 km/h, but stays almost constant with a further speed increase from 300 to 400 km/h.

Finding a simple and practical method to improve the dynamic behaviour of a specific structure is always desirable in civil and mechanical engineering. The railway catenary system is the overhead power line above the track, interacting together with the train-based pantograph to transfer electric power. Due to vertical stiffness variation and a propagating wave along the catenary, the fluctuation of the contact force becomes significant with operational speed increasing. Therefore, this has become one of the key factors which limits the operational speed and service life of key components. Wire misalignment, structural errors and uneven mass distribution of the catenary can further deteriorate the contact stability. In order to achieve a higher speed on existing lines, the catenary needs large-scale modification implying long out-off-service time. From the designing aspect, all components directly fixed to the catenary, like clamps, steady arms and other fittings, are made as light and small as possible to minimize disturbances. However, in other engineering applications, some well-designed additional mass systems are adopted aiming to improve their dynamic performance. In order to take advantage of these unavoidable masses on the catenary, an investigation on lumped-mass distribution in single-pantograph and multi-pantograph operations is performed with help of a 3D pantograph-catenary finite element (FE) model. The results show that a rightly-tuned mass, here the implementing location and the elasticity of its connection, can positively change the dynamic performance without implementing large-scale modification to the existing system. Through a brief discussion on the mechanism of this positive effect, this paper proposes that applying some artificial tuned-mass system can be a possible method to overcome unfavourable working conditions or even allow speed increase on existing lines.

In this work a methodology is presented to assess running gears with respect to wheel and rail rolling contact fatigue (RCF). This assessment is based on wheel/rail contact data for different wheel profile wear states taken from a wheel profile prediction methodology. The approach allows e.g. The assessment of rail RCF in different curve radii in a cumulative way (sum of damage over lifetime of wheel profiles). Furthermore, RCF assessments can be done at different wear states of the wheel profiles to get insight how the contribution to wheel and rail RCF varies depending on the evolution of the wheel profiles. The presented methodology is exemplary applied to two bogie types, the UIC-Y25 standard bogie and the so called FR8RAIL bogie with a mechanical wheelset steering device. The presented methodology is a helpful tool e.g. To optimize vehicles already in an early stage of the development process. 

Track geometry quality and dynamic vehicle response are closely related, but do not always correspond with each other in terms of maximum values and standard deviations. This can often be seen to give poor results in analyses with correlation coefficients or regression analysis. Measured data from the EU project DynoTRAIN is used in this paper to evaluate track-vehicle response. A single degree of freedom model is used as inspiration to divide track-vehicle interaction into three parts, which are analysed in terms of correlation. One part, the vertical axle box acceleration divided by vehicle speed squared (z(w)/v(2)) and the second spatial derivative of the vertical track irregularities (z(t)''), is shown to be the weak link with lower correlation coefficients than the other parts. Future efforts should therefore be directed towards investigating the relation between axle box accelerations and track irregularity second derivatives, while also including more vehicles.

Track geometry quality and dynamic vehicle response are closely related, but do not always correspond with each other in terms of maximum values and standard deviations. This can often be seen to give poor results in analyses with correlation coefficients or regression analysis. Measured data from both the EU project DynoTRAIN and the Swedish Green Train (Gröna Tåget) research programme is used in this paper to evaluate track–vehicle response for three vehicles. A single degree of freedom model is used as an inspiration to divide track–vehicle interaction into three parts, which are analysed in terms of correlation. One part, the vertical axle box acceleration divided by vehicle speed squared ((Formula presented.)) and the second spatial derivative of the vertical track irregularities ((Formula presented.)), is shown to be the weak link with lower correlation coefficients than the other parts. Future efforts should therefore be directed towards investigating the relation between axle box accelerations and track irregularity second derivatives.

The contact model between wheel and rail is significant for predicting wear of the wheel profile with help of multi-body dynamics simulation. Among the contact models, Hertz’s theory and Fastsim algorithm are widely used in MBS software due to high computational efficiency and acceptable precision. But with respect to wear, the accuracy of such a contact model is insufficient, especially for predicting the wear distribution. A new non-elliptic contact model called ANALYN/FaStrip with fast calculation speed has been proposed to improve the precision for both normal and tangential solutions. This paper investigates the influence of this new contact model on the wear calculation by comparing with Hertz/Fastsim in terms of contact pressure and creep forces, and finally indicates the difference of wear depth calculated by the two contact models. The results illustrate that significant improvements can be gained by implementing ANALYN/FaStrip into the wheel wear prediction.

KTH railway group intends to revive the old two-axle rail vehicle concept and reintroduce it as a modern passenger vehicle with the operational speed up to 200 km/h. Two-axle rail vehicles are cheap, light and easy to maintain but have different running limitations. Different active suspension technologies can be used to improve on these limitations. One challenge with introducing different active suspension systems on vehicles with just one level of suspension is the high risk of active systems interfering in each other’s objectives. This study investigates the interference of active comfort and wheelset stability controllers.