A railway switch is a vital component for its safe, reliable, and time-bound operations. Faults in switches are common in locations experiencing winters due to snow or ice buildup, despite using heating systems. The majority of switches are electrically heated, and guidelines for their efficient operations have been studied in this work. A computational model has been created to understand the temperature distributions in switch heating systems, and it has been verified from the annual heating data of an operational switch in Sweden. The results from a parametric study by varying ambient temperature, wind load, and heating element power can be used to implement heating control strategies in existing heaters, which will support their sustainable operations. In addition, the feasibility of using ground-source borehole renewable energy is also investigated for different bedrocks. The results of the temperature drop in the borehole for a constant winter heating load over 15 years give insights on the potential usage of ground heat in switch heating.

The continuous movement of high-speed train results in the pantograph interacting with a long catenary structure. The traditional methods based on the Lagrangian description can only model the whole long catenary structure, which decreases their calculation efficiency. In this work, a reduced pantograph–catenary interaction model is developed to accurately and efficiently simulate the pantograph-catenary interaction with the long catenary structure. In the model, the long catenary is reduced to a small region around the moving pantograph, and the arbitrary Lagrangian‒Eulerian (ALE) method and modal superposition method (MSM) are used to model this small area. The pantograph is modeled as a multi-rigid body system. The pantograph and reduced catenary model formulate the reduced pantograph–catenary interaction model. Because the long catenary structure is reduced to a small moving region, the number of degrees of freedom (DOF) of the model is significantly decreased. The present model is validated by the EN 50318:2018 standard with a long catenary structure considered. The calculation results show that the present model is accurate and efficient in the investigation of long-term pantograph-catenary interaction dynamics.

A thermomechanical model has been developed and implemented to couple temperature, thermal expansion, contact, and wear using the finite element method. This three-dimensional, transient, and nonlinear model is unconditionally stable because of the use of an implicit solver. The weak form of the nonlinear heat transfer and elasticity equations has been derived, incorporating penalty contact, conduction, convection, radiation, and deformation. Several boundary conditions, including Dirichlet, Neumann, and Robin conditions, have been applied. We focus on mechanical train brakes due to their strong thermomechanical coupling effect. The simulation results have been validated against full-scale experimental data. Additionally, mesh sensitivity and time step sensitivity analyses are conducted to further assess the model’s accuracy. Friction heat is calculated at each time step through contact conditions, enabling the identification of hot spots and thermal cracks. The results demonstrate that this thermomechanical model is both efficient and robust. This model has been open-sourced, providing a powerful tool for advanced research in thermomechanical multiphysics analysis.

The emissions from traditional fossil heavy-duty trucks have become a conspicuous issue worldwide. The electrical road system (ERS) can offer a viable solution for achieving zero CO₂ emissions and has high energy efficiency in long-distance road cargo transport. While many kinds of pantograph structures have been developed for the ERS, their corresponding pantograph-catenary dynamic characteristics under different road conditions have not been investigated. This work performs a numerical study on the dynamics of the pantograph-catenary interaction of an ERS considering different pantograph structures. First, a pantograph-catenary-truck-road model is proposed. The reduced catenary model and reduced-plate model transmission method are used to minimize model scale. Three different types of ERS pantograph structures are considered in the model. After validation, the pantograph-catenary dynamics under the influence of truck-road interactions with complex road roughness and different pantographs are studied and compared. The corresponding vibration transmission mechanism is further focused. The results show that the truck-road interaction has a significant effect on the pantograph-catenary interaction, but the pantograph with only one lower and upper arm can isolate the roll vibration motion transmission from the truck to the collector head, which has the best dynamic performance and is suggested for use in the ERS.

Rail corrugation is a typical rail cyclical disease which often occurs on heavy haul, urban transit, and high-speed railways. Rail corrugation has a significant impact on vehicle dynamic performance, especially on the axle box acceleration. It may cause the bolts of axle box to loosen or break the rail fastener, and even affect the operation of vehicle. Therefore, it is necessary to discover rail corrugation in time and to repair it by rail grinding, which is an important way to improve the safety of the vehicle. A numerical analysis method based on adaptive time-frequency feature extraction is proposed in this paper. First, acceleration sensors are installed on both the left and right side of the axle box. Then the vibration features of the axle box are extracted according to the line mileage segmentation based on the adaptive time-frequency feature extraction method proposed in this paper. Finally, the impact of different wavelength and different section length of rail corrugation is compared using field test data. The test results show that the method proposed in this paper can accurately extract the features of different wavelength and different section length of rail corrugation. Moreover, compared with traditional methods, this method is proven to be strongly adaptive and highly accurate.

The pantograph-catenary powered heavy truck system has been built in many countries to reduce carbon emissions and increase transportation efficiency of the heavy truck. However, the dynamics of the pantograph-catenary interaction system under the influence of truck-road interaction has not been widely investigated so far. In this work, the dynamic behavior of the pantograph-catenary powered heavy truck system is studied. A pantograph-catenary-truck-road interaction model is formulated based on the existing test line, where the reduced catenary model and reduced-plate model transmission method are used to minimize the demand on calculation effort. Then, the influence of different road qualities on pantograph-catenary interaction dynamics is studied. The results show that the truck-road interaction has a heavy influence on pantograph-catenary interaction dynamics in 1-5 Hz frequency domain and the corresponding vibration should be considered and isolated to optimize the dynamic behavior of the pantograph-catenary system.

This work applies numerical simulations and a drive cycle perspective for the estimation of wear on rail vehicle collector strips using an existing heuristic wear model. As it is crucial to understand the origin of wear patterns to ensure long service life, the proposed analysis method allows to identify the contribution of each drive stage during operation to the wear pattern and to compare their wear rates against each other. Input data is created by numerically simulating the power intake of a rail vehicle during a drive cycle between two stations and extracting power-speed couples for characteristic drive stages. The dynamic interaction between pantograph and catenary is then simulated using a FE-representation of the catenary and a pantograph model with two individually suspended flexible collector strips. Using these transient time signals as input data to the heuristic wear model, the lateral wear distribution along both collector strips can be estimated for each drive stage. Here, a representative run of a Swedish X2 higher speed train is used as a case example. The results show that mechanical wear dominates on average, but that there is a considerable electrical wear intensity, especially during acceleration. This contribution is however relativised by the short distance covered in this stage, and the total wear pattern is dictated by the cruising stage. The wear patterns show high dependence on the evaluated frequency range in the force signal.

Increased equivalent conicity of wheels because of hollow wear during long-term operation influences the ride comfort performance of Chinese high-speed trains. To investigate the evolution of wheel wear, a high-speed train operating on the Beijing-Shanghai Railway line at maximum operational speed of 350 km/h is monitored over a time of 1.5 years. An MBS based wear calculation software tool of KTH using stochastic simulation inputs has been used for wear prediction, where the vehicle suspension parameters and global structural modes of car-body and bogie frame have been identified using roller rig measurements and dynamic track measurements as well to validate the simulation models. The calculated wear is then validated against measurements by calibrating the wear rate coefficients. The influence of initial conicity on the lateral wear distribution is analyzed. Wheel profiles with lower initial conicities result in significantly less wear but more vibrations which possibly worsen the ride comfort. Increasing the roll-stiffness shows to be an effective way to damp the low frequency vibrations for the low conicity wheel while resulting in low wear. The suspension parameters and initial conicity which give the most stable equivalent conicity evolution and best ride comfort are selected for field tests.

This compendium is mainly intended for the MSc education in rail vehicle engineering at KTH Royal Institute of Technology. It now appears in its 4th edition. Together with the compendium "Part 2: Rail Vehicles", they comprise 20 chapters and more than 600 pages.

This compendium is mainly intended for the MSc education in rail vehicle engineering at KTH Royal Institute of Technology. It now appears in its 4th edition. Together with the compendium "Part 1: Rail Systems", they comprise 20 chapters and more than 600 pages.