Articoli di riviste: "COMPUTATIONAL MODELLING OF RAIL WHEEL"

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Fajdiga, Gorazd, Matjaž Šraml e Janez Kramar. "Modelling of Rolling Contact Fatigue of Rails". Key Engineering Materials 324-325 (novembre 2006): 987–90. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.987.

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Rail dark spot defect, also termed as squat failure or shelling, is a rolling contact fatigue failure which occurs frequently on the high speed traffic railway rails. The main goal of this study is to develop a computational model for simulation of the squat phenomena on rails in rail-wheel contact. The proposed computational model consists of two parts: (i) Contact Fatigue Crack Initiation (CFCI) and (ii) Contact Fatigue Crack Propagation (CFCP). The results of proposed unified model enable a computational prediction of a probable number of loading cycles that a wheel-rail system can sustain before development of the initial crack in the rail, as well as the number of loading cycles required for a crack to propagate from initial to critical length, when the final fatigue failure (squat) can be expected to occur.

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An, Boyang, Jing Wen, Panjie Wang, Ping Wang, Rong Chen e Jingmang Xu. "Numerical Investigation into the Effect of Geometric Gap Idealisation on Wheel-Rail Rolling Contact in Presence of Yaw Angle". Mathematical Problems in Engineering 2019 (2 aprile 2019): 1–14. http://dx.doi.org/10.1155/2019/9895267.

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For a fast calculation of vehicle-track dynamics and wheel-rail contact mechanics, wheel-rail contact geometric gap is usually idealised in elliptic or nonelliptic form. These two idealisations deviate from the actual one if the lateral combined curvature within the contact patch is not constant or the yaw angle of wheelset exists. The influence of these idealisations on contact solution has not yet been deeply understood, and thus the accuracy of simplified contact modelling applied to vehicle-track dynamics and wheel-rail contact mechanics remains uncertain. This paper presents a numerical methodology to treat 3D wheel-rail rolling contact, in which the asymmetric geometric gap due to yaw angle is fully taken into account. The attention of this work is placed on investigating the effect of geometric gap idealisation on wheel-rail contact force, rolling contact solution, and wear distribution. It can help with the effective wheel-rail contact modelling on the computation of both vehicle-track dynamics and wheel-rail contact mechanics.

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Xu, Lei, Qiang Zhang, Zhiwu Yu e Zhihui Zhu. "Vehicle–track interaction with consideration of rail irregularities at three-dimensional space". Journal of Vibration and Control 26, n. 15-16 (14 gennaio 2020): 1228–40. http://dx.doi.org/10.1177/1077546319894816.

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Modelling of vehicle–track interaction has long been a hot and interesting topic. In multibody dynamics based on force-equilibrium methods, Hertzian contact and creep theories have been applied in vehicle–track model constructions. In another aspect, the complementarity-based methods have also been widely used in establishing vehicle–track interaction, but still having drawbacks on characterization of wheel–rail contact geometry/creepage in three-dimensional space. In this study, we draw essences from methodologies of refined wheel–rail coupling models and energy-variational principle, and a model for vehicle–track three-dimensional interactions with inclusion of rail irregularity excitations is newly developed. This model possesses high accuracy compared with Hertzian contact, FastSim, and vehicle–track coupled model in the middle-low frequency domain, and also, the advantages in computational stability are possessed. In this model, the unevenness of rail irregularities at the three-dimensional space is preliminarily considered by taking a hypothesis of normal distribution and accordingly, the wheel–rail three-dimensional constraint equations are presented. Extensively, a series of numerical examples are shown to verify the effectiveness and engineering practicability of this model. Besides, the influence of rail three-dimensional irregularities on the dynamic performance of vehicle–track systems is further explored, which shows when the trochoid of the wheel–rail contact points changes rapidly, the additional inertial effects brought out by rail irregularities might exert great influence on wheel–rail forces.

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Dižo, Ján, Miroslav Blatnický, Jozef Harušinec e Andrej Suchánek. "Assessment of Dynamics of a Rail Vehicle in Terms of Running Properties While Moving on a Real Track Model". Symmetry 14, n. 3 (6 marzo 2022): 536. http://dx.doi.org/10.3390/sym14030536.

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Simulation computations represent a very effective tool for investigating operational characteristics and behaviours of vehicles without having a real product. The rail vehicles sector is typical, in that simulation computations including multibody modelling of individual vehicles (i.e., wagons) as well as entire trainsets are widely used. In the case of designing rail vehicles, running safety and ride comfort are two of the most important assessment areas. The presented work is focused on the research of the dynamical effects of a rail vehicle while running on a railway track created in a commercial multibody model. There is a lot of research focused on the investigation of dynamic performances while a rail vehicle is running on a flexible railway track. The real operation of a rail vehicle meets problems on track, where the stiffness-damping parameters of a railway track vary in transient sections (e.g., the exit of a tunnel). This work brings a contribution to research related to the assessment of the dynamic response of a rail vehicle on a chosen track section. A passenger railway vehicle is chosen as a reference multibody model. Simulation computations were performed for three different railway track models, i.e., for a rigid track model and for a flexible track model defined in two different manners. The stiffness-damping parameters of the rail vehicle are defined symmetrically in relation to the longitudinal axis of the vehicle, e.g., they are the same values for the left and right side. The centre of gravity is not located symmetrically, but it is partially shifted in the lateral direction. This can be observed in the results of wheel forces and their waveforms. There are evaluated values and waveforms of the vertical wheel forces, the lateral wheel forces and the derailment quotient. The obtained results have revealed the influence of the railway track formulation in the model on the output parameters.

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Baeza, L., F. J. Fuenmayor, J. Carballeira e A. Roda. "Influence of the wheel-rail contact instationary process on contact parameters". Journal of Strain Analysis for Engineering Design 42, n. 5 (1 luglio 2007): 377–87. http://dx.doi.org/10.1243/03093247jsa247.

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The rapid convergence of the tangential rolling contact parameters to their stationary values, combined with the high computational cost associated with calculations using instationary models, has meant that stationary models are usually employed in railway dynamics. However, the validity of stationary models when the applied contact conditions are subjected to rapid changes has not been sufficiently investigated. With the objective of deducing the effects of the evolution of the instationary process on the contact parameters, the tangential contact problem is solved for a set of reference conditions. For this purpose a calculation model is adapted, from which it is possible to analyse the evolution of the contact parameters when the forces exerted between rail and wheel are subjected to rapid changes. From the calculations made, situations impossible to simulate by means of stationary theories are obtained according to the frequency of variation in the forces, such as slip zones in the leading edge of the contact area and reverse contact (locally, the traction field is opposite to the direction of the external force transmitted to the contact).

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Zhao, Jing, Edwin A. H. Vollebregt e Cornelis W. Oosterlee. "EXTENDING THE BEM FOR ELASTIC CONTACT PROBLEMS BEYOND THE HALF-SPACE APPROACH". Mathematical Modelling and Analysis 21, n. 1 (26 gennaio 2016): 119–41. http://dx.doi.org/10.3846/13926292.2016.1138418.

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The boundary element method (BEM) is widely used in fast numerical solvers for concentrated elastic contact problems arising from the wheel-rail contact in the railway industry. In this paper we extend the range of applicability of BEM by computing the influence coefficients (ICs) numerically. These ICs represent the Green’s function of the problem, i.e. the surface deformation due to unit loads. They are not analytically available when the half-space is invalid, for instance in conformal contact. An elastic model is proposed to compute these ICs numerically, by the finite element method (FEM). We present a detailed investigation to find proper strategies of FEM meshing and element types, considering accuracy and computational cost. Moreover, the effects of computed ICs to contact solutions are examined for a Cattaneo shift contact problem. The work in this paper provides a guidance to study fast solvers for the conformal contact.

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An, Boyang, Daolin Ma, Ping Wang, Jiayi Zhou, Rong Chen, Jingmang Xu e Dabin Cui. "Assessing the fast non-Hertzian methods based on the simulation of wheel–rail rolling contact and wear distribution". Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 234, n. 5 (9 maggio 2019): 524–37. http://dx.doi.org/10.1177/0954409719848592.

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This paper aims at assessing several fast non-Hertzian methods, coupled with two wear models, based on the wheel–rail rolling contact and wear prediction. Four contact models, namely Kik-Piotrowski's method, Linder's method, Ayasse-Chollet's STRIPES algorithm and Sichani's ANALYN algorithm are employed for comparing the normal contact. For their tangential modelling, two tangential algorithms, i.e. FASTSIM and FaStrip, are used. Two commonly used wear models, namely the Archard (extended at the KTH Royal Institute of Technology) and USFD (developed by the University of Sheffield based on T-gamma approach), are further utilized for wear distribution computation. All results predicted by the fast non-Hertzian methods are evaluated against the results of Kalker's CONTACT code using penetration as the input. Since the two wear models adopt different expressions for calculating the wear performance, the attention of this paper is on assessing which one is more suitable for the fast non-Hertzian methods to utilize. The comparison shows that the combination of the USFD wear model with any of the fast non-Hertzian methods agrees better with CONTACT+USFD. In general, ANALYN+FaStrip is the best solution for the simulation of the wheel–rail rolling contact, while STRIPES+FASTSIM can provide better accuracy for the maximum wear depth prediction using the USFD wear model.

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Ramalho, A. "Wear modelling in rail–wheel contact". Wear 330-331 (maggio 2015): 524–32. http://dx.doi.org/10.1016/j.wear.2015.01.067.

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Wu, Qing, Maksym Spiryagin, Peter Wolfs e Colin Cole. "Traction modelling in train dynamics". Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 233, n. 4 (30 agosto 2018): 382–95. http://dx.doi.org/10.1177/0954409718795496.

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This paper presents five locomotive traction models for the purpose of train dynamics simulations, such as longitudinal train dynamics simulations. Model 1 is a look-up table model with a constant force limit to represent the adhesion limit without modelling the wheel–rail contact. Model 2 is improved from Model 1 by empirically simulating locomotive sanding systems, variable track conditions and traction force reduction due to curving. Model 3 and Model 4 have included modelling of the wheel–rail contact and traction control. Model 3 uses a two-dimensional locomotive model while Model 4 uses a three-dimensional locomotive. Model 5 is based on Model 2 and developed to simulate hybrid locomotives. Demonstrative simulations are presented for the case of longitudinal train dynamics. The results show that the consideration of locomotive sanding systems, variable track conditions and traction force reduction have evident implications on the simulated traction forces. There can be up to 30% difference in the simulated traction forces. Simulated traction forces by models that consider the wheel–rail contact are about 10–15% lower than those simulated by models without consideration of the wheel–rail contact. This is mainly due to the variable friction in the wheel–rail contact and conservative traction control schemes.

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Tao, Gongquan, Zefeng Wen, Xin Zhao e Xuesong Jin. "Effects of wheel–rail contact modelling on wheel wear simulation". Wear 366-367 (novembre 2016): 146–56. http://dx.doi.org/10.1016/j.wear.2016.05.010.

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11

Dailydka, Stasys, Leonas Povilas Lingaitis, Sergey Myamlin e Vladimir Prichodko. "MODELLING THE INTERACTION BETWEEN RAILWAY WHEEL AND RAIL". TRANSPORT 23, n. 3 (30 settembre 2008): 236–39. http://dx.doi.org/10.3846/1648-4142.2008.23.236-239.

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The article presents a mathematical model for assessing the real operating conditions of railway rolling stock, taking into account the situations when the wheel loses contact with rail. The obtained amplitudinal fluctuation characteristics depend on the set roughness function and the running speed of the wheel. When calculating dynamic processes, the contact between wheel and rail should be considered unstable. With the increase of speed, the impact of this instability increases.

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Thompson, D. J. "Theoretical Modelling of Wheel-Rail Noise Generation". Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 205, n. 2 (luglio 1991): 137–49. http://dx.doi.org/10.1243/pime_proc_1991_205_227_02.

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Ma, Xiaoqi, Lin Jing e Liangliang Han. "A computational simulation study on the dynamic response of high-speed wheel–rail system in rolling contact". Advances in Mechanical Engineering 10, n. 11 (novembre 2018): 168781401880921. http://dx.doi.org/10.1177/1687814018809215.

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The dynamic wheel–rail responses during the rolling contact process for high-speed trains were investigated using the explicit finite element code LS-DYNA 971. The influence of train speed on the wheel–rail contact forces (including the vertical, longitudinal, and lateral forces), von Mises equivalent stress, equivalent plastic strain, vertical acceleration of the axle, and the lateral displacement of the initial contact point on the tread, were examined and discussed. Simulation results show that the lateral and longitudinal wheel–rail contact forces are very smaller than the corresponding vertical contact forces, and they seem to be insensitive to train speed. The peak value of dynamic vertical wheel–rail contact force is approximately 2.66 times larger than the average quasi-static value. The elliptical wheel–rail contact patches have multiple stress extreme points due to the plastic deformation of the wheel tread and top surface of the rail. The vertical acceleration value of the axle in the steady condition is around ±5 m/s2 for the perfected wheel–rail system with the running speed below 300 km/h.

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Jelila, Y. D., H. G. Lemu, W. Pamuła e G. G. Sirata. "Fatigue life analysis of wheel-rail contacts at railway turnouts using finite element modelling approach." IOP Conference Series: Materials Science and Engineering 1201, n. 1 (1 novembre 2021): 012047. http://dx.doi.org/10.1088/1757-899x/1201/1/012047.

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Abstract The article deals with wheel-rail contact analysis at railway turnout using a finite element modelling approach. The focus is understanding the wheel-rail contact problems and finding the means of reducing these problems at railway turnouts. The main aim of the work reported in this article is to analyse fatigue life and simulate the wheel-rail contact problems for a repeated wheel loading cycle by considering the effect of normal and tangential contact force impact under different vehicle loading conditions. The study investigates the impact of tangential contact force generated due to different-angled shapes of the turnout and aims to reveal how it affects the life of contacting surfaces. The obtained results show that the maximum von-Mises equivalent alternating stress, maximal fatigue sensitivity, and maximum hysteresis loop stresses were observed under tangential contact force. These maximum stresses and hysteresis loops are responsible for rolling contact fatigue damage, and excessive deformation of the wheel-rail contact surface. At a constant rotational velocity, the tangential contact force has a significant impact on the fatigue life cycle and wheel-rail material subjected to fatigue damage at lower cycles compared to the normal contact force. The finite element modelling analysis result indicated that the contact damages and structural integrity of the wheel-rail contact surface are highly dependent on contact force type and can be affected by the track geometry parameters.

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Bhaskar, A., K. L. Johnson, G. D. Wood e J. Woodhouse. "Wheel-rail dynamics with closely conformal contact Part 1: Dynamic modelling and stability analysis". Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 211, n. 1 (1 gennaio 1997): 11–26. http://dx.doi.org/10.1243/0954409971530860.

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Observations on the Vancouver mass transit system suggest that noise, vibration and corrugation of the rail appear to be associated with close conformity between the transverse profiles of the wheel and rail. To investigate this, a dynamic model of the wheel and rail under conditions of close conformity has been developed. Previous work has suggested that motion of the wheel could be neglected, so the model comprises two subsystems: (a) the rail and its supports, and (b) the contact between wheel and rail. A dynamic model of a continuously supported rail is presented, which is consistent with similar models in the literature. Conformal contact has been represented in two ways: (a) as a single highly eccentric elliptical contact, and (b) as a two-point contact. Novel ‘rolling contact mechanics’ have been incorporated in both these models. The complete system is closed: oscillations of the rail give rise to fluctuating contact forces, which in turn excite the rail. A linear stability analysis of the system shows it to be stable under all conditions examined, thus precluding the possibility of self-excited oscillations occurring on a perfectly smooth rail. The model can then be used to investigate the forced response to existing roughness on the railhead, which is the subject of a companion paper (1).

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Pradhan e Samantaray. "A Recursive Wheel Wear and Vehicle Dynamic Performance Evolution Computational Model for Rail Vehicles with Tread Brakes". Vehicles 1, n. 1 (17 aprile 2019): 88–114. http://dx.doi.org/10.3390/vehicles1010006.

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The increased temperature of the rail wheels due to tread braking causes changes in the wheel material properties. This article considers the dynamic wheel material properties in a wheel wear evolution model by synergistically combining a multi-body dynamics vehicle model with a finite element heat transfer model. The brake power is estimated from the rail-wheel contact parameters obtained from vehicle model and used in a finite element model to estimate the average wheel temperature. The wheel temperature is then used for wheel wear computation and the worn wheel profile is fed to the vehicle model, thereby forming a recursive simulation chain. It is found that at a higher temperature, the softening of the rail-wheel material increases the rate of wheel wear. The most affected dynamic performance parameter of the vehicle is found to be the critical speed, which reduces sharply as the wheel wear exceeds a critical limit.

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Lewandowski, Mirosław, Wiesław Grzesikiewicz, Michał Makowski e Katarzyna Rutczyńska-Wdowiak. "Modelling and simulation of Adhesion of the RAIL vehicle". Journal of Automation, Electronics and Electrical Engineering 4, n. 2 (31 dicembre 2022): 17–21. http://dx.doi.org/10.24136/jaeee.2022.008.

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In the paper we consider the issue related to the phenomenon of wheel-to-rail adhesion. This issue concerns self-excited vibrations in the area of wheel-rail contact, caused by unstable friction. Such friction is characterized by decreasing values of the friction coefficient with increasing slipping velocity. The paper includes mathematical formulation of the problem and presents the method for solving it. In addition, a simulation of elementary vehicle driving was performed. During the simulation, self-excited vibrations arose during wheel slip caused by high driving torque. The paper presents graphs illustrating the tangential force and the slipping velocity during these vibrations.

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Coleman, I., E. Kassa e R. Smith. "Wheel-Rail Contact Modelling within Switches and Crossings". International Journal of Railway Technology 1, n. 2 (2012): 45–66. http://dx.doi.org/10.4203/ijrt.1.2.3.

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Trummer, Gerald, Zing Siang Lee, Roger Lewis e Klaus Six. "Modelling of Frictional Conditions in the Wheel–Rail Interface Due to Application of Top-of-Rail Products". Lubricants 9, n. 10 (8 ottobre 2021): 100. http://dx.doi.org/10.3390/lubricants9100100.

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The coefficient of friction between a wheel tread and the top of the rail should be maintained at intermediate levels to limit frictional tangential contact forces. This can be achieved by applying top-of-rail products. Reducing the coefficient of friction to intermediate levels reduces energy consumption and fuel costs, as well as damage to the wheel and rail surfaces, such as, e.g., wear, rolling contact fatigue, and corrugation. This work describes a simulation model that predicts the evolution of the coefficient of friction as a function of the number of wheel passes and the distance from the application site for wayside application of top-of-rail products. The model considers the interplay of three mechanisms, namely the pick-up of product by the wheel at the application site, the repeated transfer of the product between the wheel and rail surfaces, and the product consumption. The model has been parameterized with data from small-scale twin disc rig experiments and full-scale wheel–rail rig experiments. Systematic investigations of the model behaviour for a railway operating scenario show that all three mechanisms may limit the achievable carry-on distance of the product. The developed simulation model assists in understanding the interplay of the mechanisms that govern the evolution of the coefficient of friction in the field. It may aid in finding optimal product application strategies with respect to application position, application amount, and application pattern depending on specific railway operating conditions.

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Chiba, Elhocine, Mourad Abdelkrim, Abderrahim Belloufi e Imane Rezgui. ""THREE-DIMENSIONAL MODELLING OF RAILS / WHEELS MANUFACTURED BY ER6 AND ER7 IN TRAMWAY APPLICATIONS "". International Journal of Modern Manufacturing Technologies 14, n. 3 (20 dicembre 2022): 38–43. http://dx.doi.org/10.54684/ijmmt.2022.14.3.38.

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The wheels and rails of the train, tram etc. are often verified from their microstructure and plastic deformation, which usually appear in the outer layer of a wheel and rail, to analyse the causes of geometrical defects by monitoring the applied loads and variation of the temperature as suggested in the literature. This paper studies the effect of thermal stress applied with variations of the loads in contact on wheel/rail for the tramway, tracking through the state of the rail to discover the causes of geometric defects started by temperature variations and loads, and applying these variations of temperature and loads to know its resistance to these climatic conditions. 3D model of temperature distrubtion and heat flow in the wheel and the rail ER6 and ER7 has been developped using the finite element method based on the COMSOL Multiphisics.

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Steenbergen, Michaël J. M. M. "Modelling of wheels and rail discontinuities in dynamic wheel–rail contact analysis". Vehicle System Dynamics 44, n. 10 (ottobre 2006): 763–87. http://dx.doi.org/10.1080/00423110600648535.

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Wu, Yi, Jing Zeng, Sheng Qu, Huailong Shi, Qunsheng Wang e Lai Wei. "Low-Frequency Carbody Sway Modelling Based on Low Wheel-Rail Contact Conicity Analysis". Shock and Vibration 2020 (21 dicembre 2020): 1–17. http://dx.doi.org/10.1155/2020/6671049.

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Low-frequency carbody swaying on China’s high-speed trains is not only an impediment to ride comfort but it may also be an operational risk under some extreme situations. To study the mechanism and mitigate the carbody swaying problem for high-speed trains, a multibody dynamics model was established based on both linear and nonlinear analyses. Whilst it is generally assumed that carbody swaying is predominantly caused by carbody hunting motion, the results in this paper has shown that, under certain boundary conditions, bogie-hunting motion can also lead to low-frequency carbody swaying. This low-frequency swaying phenomenon was also found to be caused by the excessively low wheel-rail contact or mismatched suspension parameters. Parametric optimization analysis was accordingly conducted from the perspective of the wheel-rail contact relationship and the suspension system. The analysis indicated that although optimizing the suspension parameters can meet the requirement of vehicle stability, bogie's vibration worsen when the wheel profiles wear over time. Overall, while rail reprofiling was found to be one of the fundamental solutions to mitigate carbody swaying, it is cost prohibitive for most routine operational applications. Thus, for economic considerations and the fact that low wheel-rail contact conicity is also a contributing factor to carbody swaying, vehicles with worn wheels can also be operated on the rail line, which was successfully verified by the field data presented in this paper.

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Guiral, A., A. Alonso, L. Baeza e J. G. Giménez. "Non-steady state modelling of wheel–rail contact problem". Vehicle System Dynamics 51, n. 1 (gennaio 2013): 91–108. http://dx.doi.org/10.1080/00423114.2012.713499.

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Cai, Guanmian, Zhihui Zhu, Wei Gong, Gaoyang Zhou, Lizhong Jiang e Bailong Ye. "Influence of Wheel-Rail Contact Algorithms on Running Safety Assessment of Trains under Earthquakes". Applied Sciences 13, n. 9 (22 aprile 2023): 5230. http://dx.doi.org/10.3390/app13095230.

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Accurate running safety assessment of trains under earthquakes is crucial to ensuring the safety of line operation. Extreme contact behaviors such as wheel flange contact and wheel jump during earthquakes will directly affect the running safety of trains. To accurately simulate a wheel-rail extreme contact state, the calculation of the normal compression amount, the normal contact stiffness, and a number of contact points are crucial in wheel-rail space contact modeling. Hence, in order to clarify the applicable algorithms during earthquakes, this paper first introduces different algorithms in three aspects mentioned above. Taking a single CRH2 motor vehicle passing through a ballastless track structure under EI-Centro wave excitation as an example, a comparative analysis of wheel-rail contact dynamics and running safety was conducted. The results showed that adopting the normal compression algorithm based on vertical penetration and the consideration of only single-point contact will result in the maximum calculation error of wheel-rail contact force to reach 339.50% and 35.00%, respectively. This significantly affects the accuracy of train safety assessment, while using the empirical formula for wheel-rail normal contact stiffness has relatively less impact. To ensure the accuracy of running safety assessment of trains during an earthquake, it is recommended to adopt the normal compression algorithm based on normal penetration and consider the multi-point contact in wheel-rail contact modelling.

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Alizadeh Kaklar, J., R. Ghajar e H. Tavakkoli. "Modelling of nonlinear hunting instability for a high-speed railway vehicle equipped by hollow worn wheels". Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 230, n. 4 (3 agosto 2016): 553–67. http://dx.doi.org/10.1177/1464419316636968.

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One of the reasons for frequent vibrations of coaches and hunting instability are hollow worn wheels. The main purpose of this paper is to investigate the effect of the wheel surface hollowing on the inconstancy and vibrations of a wagon. Considering the nonlinearity of the hollow surface, as well as both single and double point wheel-rail contacts are the significant points of this study. In order to do this, 800 wheel profiles of 100 coaches were measured in a controlled manner in a period of six months as an infield study. Statistical methods were used to categorize the measured hollow wheel profiles and select eight of the most observed ones. Then, a nonlinear mathematical model of a high-speed railway vehicle with 21 degrees of freedom was used for dynamic analysis of a wagon equipped by the hollow worn wheels on a tangent track. In order to model the effect of hollowing on the dynamic behaviour of the vehicle, the nonlinearity of wheel profile was taken into account. Also, both single and double point wheel-rail contacts were considered for accurate modelling of the wheel-rail interaction forces. Based on the results of the study, the tread hollowing must be considered as an independent dimensional parameter in periodic inspections. Also, it was concluded that worn wheels should be inspected regularly and re-profiled before their false flanges exceed a limit of 2 mm, in order to prevent the hunting phenomenon, and ensure being away from derailment of a passenger railway vehicle. Validation of the mathematical modelling was performed through the modelling of vehicle in ADAMS/Rail and comparing the results.

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Shih, J. Y., R. Ambur, H. C. Boghani, R. Dixon e E. Stewart. "A New Switch and Crossing Design: Introducing the Back to Back Bistable Switch". Journal of Civil Engineering and Construction 9, n. 4 (15 novembre 2020): 175–86. http://dx.doi.org/10.32732/jcec.2020.9.4.175.

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A new track swtich and crossing (S&C), the back to back bistable (B2B) switch, is proposed that has shown potential to significantly reduce the wheel/rail contact forces through the switch due to its more continuous wheel/rail contact interface and more uniform track stiffness arising from the elimination of the crossing nose. This offers a major reduction on maintenance cost of future S&Cs. The paper explains the concept and identifies the design guidelines for a current layout and uses vehicle/turnout dynamic modelling to predict wheel rail forces through a switch to identify performance improvements relative to a conventional S&C. Both multi-body simulation (MBS) and Finite Element (FE) model have been developed to account for dynamic and thermal analysis. The new design has shown improvements in lateral and vertical wheel-rail contact forces and less relative rail displacements due to thermal effect compared to the conventional S&C.

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Pombo, João, e Jorge Ambrosio. "A computational efficient general wheel-rail contact detection method". Journal of Mechanical Science and Technology 19, S1 (gennaio 2005): 411–21. http://dx.doi.org/10.1007/bf02916162.

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Croft, B. E., C. J. C. Jones e D. J. Thompson. "Modelling the effect of rail dampers on wheel–rail interaction forces and rail roughness growth rates". Journal of Sound and Vibration 323, n. 1-2 (giugno 2009): 17–32. http://dx.doi.org/10.1016/j.jsv.2008.12.013.

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Pieringer, A., W. Kropp e J. C. O. Nielsen. "The influence of contact modelling on simulated wheel/rail interaction due to wheel flats". Wear 314, n. 1-2 (giugno 2014): 273–81. http://dx.doi.org/10.1016/j.wear.2013.12.005.

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Sichani, M. Sh, R. Enblom e M. Berg. "Non-Elliptic Wheel-Rail Contact Modelling in Vehicle Dynamics Simulation". International Journal of Railway Technology 3, n. 3 (2014): 77–96. http://dx.doi.org/10.4203/ijrt.3.3.5.

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31

Burgelman, Nico, Matin Sh Sichani, Roger Enblom, Mats Berg, Zili Li e Rolf Dollevoet. "Influence of wheel–rail contact modelling on vehicle dynamic simulation". Vehicle System Dynamics 53, n. 8 (14 maggio 2015): 1190–203. http://dx.doi.org/10.1080/00423114.2015.1039550.

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32

Rovira, A., A. Roda, M. B. Marshall, H. Brunskill e R. Lewis. "Experimental and numerical modelling of wheel–rail contact and wear". Wear 271, n. 5-6 (giugno 2011): 911–24. http://dx.doi.org/10.1016/j.wear.2011.03.024.

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33

Alonso, Asier, Carlos Casanueva, Javier Perez e Sebastian Stichel. "Modelling of rough wheel-rail contact for physical damage calculations". Wear 436-437 (ottobre 2019): 202957. http://dx.doi.org/10.1016/j.wear.2019.202957.

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34

Zhang, ShuGuang, WeiHua Zhang e XueSong Jin. "Dynamics of high speed wheel/rail system and its modelling". Chinese Science Bulletin 52, n. 11 (giugno 2007): 1566–75. http://dx.doi.org/10.1007/s11434-007-0213-1.

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35

THOMPSON, D. J., e C. J. C. JONES. "A REVIEW OF THE MODELLING OF WHEEL/RAIL NOISE GENERATION". Journal of Sound and Vibration 231, n. 3 (marzo 2000): 519–36. http://dx.doi.org/10.1006/jsvi.1999.2542.

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36

Zhong, Shuoqiao, Xinbiao Xiao, Zefeng Wen e Xuesong Jin. "Effect of wheelset flexibility on wheel–rail contact behavior and a specific coupling of wheel–rail contact to flexible wheelset". Acta Mechanica Sinica 32, n. 2 (25 agosto 2015): 252–64. http://dx.doi.org/10.1007/s10409-015-0441-6.

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37

Lisowski, Filip, e Edward Lisowski. "Optimization of ER8 and 42CrMo4 Steel Rail Wheel for Road–Rail Vehicles". Applied Sciences 10, n. 14 (8 luglio 2020): 4717. http://dx.doi.org/10.3390/app10144717.

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Abstract (sommario):

Railway track maintenance services aim to shorten the time of removing failures on the railways. One of the most important element that shorten the repair time is the quick access to the failure site with an appropriate equipment. The use of road-rail vehicles is becoming increasingly important in this field. In this type of constructions, it is possible to use proven road vehicles such as self-propelled machines or trucks running on wheels with tires. Equipping these vehicles with a parallel rail drive system allows for quick access to the failure site using both roads and railways. Steel rail wheels of road-rail vehicles are designed for specific applications. Since the total weight of vehicle is a crucial parameter for roadworthiness, the effort is made to minimize the mass of rail wheels. The wheel under consideration is mounted directly on the hydraulic motor. This method of assembly is structurally convenient, as no shafts or intermediate couplings are required. On the other hand, it results in strict requirements for the wheel geometry and can cause significant stress concentration. Therefore, the problem of wheel geometry optimization is discussed. Consideration is given to the use of ER8 steel for railway application and 42CrMo4 high-strength steel. Finite element analysis within Ansys software and various optimization tools and methods, such as random tool, subproblem approximation method and first-order method are applied. The obtained results allow to minimize the rail wheel mass with respect to the used material. Moreover, computational demands and methods leading to the best results are compared.

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38

Gautam, Aishwarya, e Sheldon I. Green. "Computational fluid dynamics–discrete element method simulation of locomotive sanders". Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 235, n. 1 (4 febbraio 2020): 12–21. http://dx.doi.org/10.1177/0954409720902897.

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Locomotive sanders are used to optimize the traction between the train wheels and the railhead by spraying sand into the interface. It has been previously shown that a large fraction of sand sprayed by the sanders does not make it through the wheel–rail nip, leading to sand wastage and thereby increasing the cost and refilling effort. In this study, pneumatic conveying of sand through the wheel–rail nip is numerically modeled through coupled computational fluid dynamics and discrete element method simulations. The gas phase, discrete phase, and coupled two-phase flows are separately validated against the literature, and the parameters affecting the deposition of sand into the nip are analyzed to determine their impact on sander efficiency. The aerodynamics associated with the particle-laden jet play a critical role in optimizing the amount of sand going through the wheel–rail interface, with the particle velocities being directly correlated with the sander efficiency. Particle–geometry interactions (e.g. particle bouncing) are found to have a negligible effect on the deposition. In the absence of crosswinds, it is recommended to employ particles with a smaller Stokes number to enhance the sander efficiency. A larger airflow rate through the nozzle is also recommended. Crosswinds strongly and adversely affect sander efficiency. The effects of crosswinds can be mitigated by reducing the nip–nozzle distance and using coarser particles.

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39

Chang, Chao, Liang Ling, Zhaoling Han, Kaiyun Wang e Wanming Zhai. "High-Speed Train-Track-Bridge Dynamic Interaction considering Wheel-Rail Contact Nonlinearity due to Wheel Hollow Wear". Shock and Vibration 2019 (31 ottobre 2019): 1–18. http://dx.doi.org/10.1155/2019/5874678.

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Wheel hollow wear is a common form of wheel-surface damage in high-speed trains, which is of great concern and a potential threat to the service performance and safety of the high-speed railway system. At the same time, rail corridors in high-speed railways are extensively straightened through the addition of bridges. However, only few studies paid attention to the influence of wheel-profile wear on the train-track-bridge dynamic interaction. This paper reports a study of the high-speed train-track-bridge dynamic interactions under new and hollow worn wheel profiles. A nonlinear rigid-flexible coupled model of a Chinese high-speed train travelling on nonballasted tracks supported by a long-span continuous girder bridge is formulated. This modelling is based on the train-track-bridge interaction theory, the wheel-rail nonelliptical multipoint contact theory, and the modified Craig–Bampton modal synthesis method. The effects of wheel-rail nonlinearity caused by the wheel hollow wear are fully considered. The proposed model is applied to predict the vertical and lateral dynamic responses of the high-speed train-track-bridge system under new and worn wheel profiles, in which a high-speed train passing through a long-span continuous girder bridge at a speed of 350 km/h is considered. The numerical results show that the wheel hollow wear changes the geometric parameters of the wheel-rail contact and then deteriorates the train-track-bridge interactions. The worn wheels can increase the vibration response of the high-speed railway bridges.

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40

Parakhnenko, Inna, Sergey Akkerman, Andrey Romanov e Oksana Shalamova. "Influence of change in frictional condition of track rail surfaces on interaction forces in the “wheel/rail” contact". E3S Web of Conferences 296 (2021): 02005. http://dx.doi.org/10.1051/e3sconf/202129602005.

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Determination of frictional condition of the running surface and side surface of the top of rail (lubrication) that ensures the best interaction of the rolling stock wheels and the rail, reduces the force action and thus ensures the track stability and reduced side wear of rails in the curved tracks is relevant for all the rail net.The objective of research is to determine the influence of frictional condition of the track rail surfaces on the interaction forces in the “wheel/rail” contact with various motion parameters (speed, radius).The theoretical and experimental methods were used in the research. The theoretical methods include multioptional computer modelling of axial and lateral forces that appear in the curved tracks during the freight train movement in the software package “Universal Mechanism”. The modelling results were processed with the use of correlation and regression analysis. The experimental methods include full-scale measurements in the existing track and results processing.According to the research results, the theoretical algorithms for assessment of influence of the running surface lubrication on the forces. The option of frictional condition of the wheel and rail interaction surfaces has been established to ensure reduction in the operating expenses for surfacing and rail replacement, energy costs for haulage of freight train.

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41

Nicholson, G. L., e C. L. Davis. "Modelling of the response of an ACFM sensor to rail and rail wheel RCF cracks". NDT & E International 46 (marzo 2012): 107–14. http://dx.doi.org/10.1016/j.ndteint.2011.11.010.

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42

Žygienė, Rasa, Marijonas Bogdevičius e Laima Dabulevičienė. "A MATHEMATICAL MODEL AND SIMULATION RESULTS OF THE DYNAMIC SYSTEM RAILWAY VEHICLE WHEEL–TRACK WITH A WHEEL FLAT / DINAMINĖS SISTEMOS „GELEŽINKELIŲ VAGONO RATAS – KELIAS“ SU RATO IŠČIUOŽA MATEMATINIS MODELIS IR MODELIAVIMO REZULTATAI". Mokslas – Lietuvos ateitis 6, n. 5 (19 dicembre 2014): 531–37. http://dx.doi.org/10.3846/mla.2014.696.

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Abstract (sommario):

A mathematical model of the system Railway Vehicle Wheel–Track with a wheel flat of a wheelset has been made. The system Railway Vehicle Wheel–Track has been examined on the vertical plane. The mathematical model of the system Railway Vehicle Wheel–Track has employed linear, nonlinear, elastic and damping discrete elements. Rail dynamics haves been described using the finite element method. The unevenness of the rail and the wheel of the wheelset have been evaluated considering the contact between the rail and the wheel flat of the wheelset. The analysis of dynamic processes taking place in a railway vehicle wheel with the wheel flat moving at speed V = 60 km/h has been accomplished. The results of mathematical modelling of the above introduced dynamic system have been presented along with graphically displayed research findings of the conducted research. Sukurtas sistemos „Geležinkelių vagono ratas – kelias“ su aširačio rato iščiuoža matematinis modelis. Sistema „Geležinkelių vagono ratas – kelias“ nagrinėjama vertikalioje plokštumoje. Sistemos „Geležinkelių vagono ratas – kelias“ matematiniame modelyje yra panaudoti tiesiniai ir netiesiniai tamprieji ir slopinimo diskretiniai elementai. Bėgio dinamika aprašoma baigtinių elementų metodu. Kontakte tarp bėgio ir aširačio rato su iščiuoža įvertinti bėgio ir aširačio rato nelygumai. Atlikta geležinkelio vagono rato su iščiuoža, judančio greičiu V = 60 km/val., dinaminių procesų analizė. Pateikti šios dinaminės sistemos matematinio modeliavimo rezultatai. Tyrimų rezultatai pavaizduoti grafiškai ir pateiktos tyrimų išvados.

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43

Sirata, G. G., H. G. Lemu, K. Waclawiak e Y. D. Jelila. "Study of rail-wheel contact problem by analytical and numerical approaches". IOP Conference Series: Materials Science and Engineering 1201, n. 1 (1 novembre 2021): 012035. http://dx.doi.org/10.1088/1757-899x/1201/1/012035.

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Abstract This study presents the rail wheel contact problems under normal and tangential categories. Both analytical and numerical approaches were used for modelling, where the analytical approach assumed elliptical contact patches based on the Hertz theory. In the numerical approach, 3D finite element models were used to investigate non-elliptical contact patches. The only elastic material model was considered in the case of Hertz theory. However, in the case of finite element analysis, both elastic and elastoplastic material models were used to simulate the material's behavior under the applied load. The elastoplastic material model was used to determine the amount of stress at which the plastic deformation starts, which enables determining the rail wheel's critical load. The commercial software ABAQUS was employed for 3D modeling and contact stress analysis. The study shows maximum stress at 3 mm from the rail wheel contact surface when the maximum load of 85 kN is applied. This initiates the cracks in the subsurface and causes the portion of the rail wheel to break off in the form of spalling after a certain time.

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44

Six, K., A. Meierhofer, G. Trummer, C. Marte, G. Müller, B. Luber, P. Dietmaier e M. Rosenberger. "Classification and Consideration of Plasticity Phenomena in Wheel-Rail Contact Modelling". International Journal of Railway Technology 5, n. 3 (2016): 55–77. http://dx.doi.org/10.4203/ijrt.5.3.3.

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45

Goryacheva, I. G., S. N. Soshenkov e E. V. Torskaya. "Modelling of wear and fatigue defect formation in wheel–rail contact". Vehicle System Dynamics 51, n. 6 (giugno 2013): 767–83. http://dx.doi.org/10.1080/00423114.2011.602419.

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46

LUNDÉN, R. "Elastoplastic modelling of subsurface crack growth in rail/wheel contact problems". Fatigue & Fracture of Engineering Materials and Structures 30, n. 10 (ottobre 2007): 905–14. http://dx.doi.org/10.1111/j.1460-2695.2007.01160.x.

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47

Schupp, Gunter, Christoph Weidemann e Lutz Mauer. "Modelling the Contact Between Wheel and Rail Within Multibody System Simulation". Vehicle System Dynamics 41, n. 5 (maggio 2004): 349–64. http://dx.doi.org/10.1080/00423110412331300326.

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48

Asih, A. M. S., K. Ding e A. Kapoor. "Modelling the Effect of Steady State Wheel Temperature on Rail Wear". Tribology Letters 49, n. 1 (30 ottobre 2012): 239–49. http://dx.doi.org/10.1007/s11249-012-0061-2.

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49

Jönsson, J., E. Svensson e J. T. Christensen. "Strain gauge measurement of wheel-rail interaction forces". Journal of Strain Analysis for Engineering Design 32, n. 3 (1 aprile 1997): 183–91. http://dx.doi.org/10.1243/0309324971513328.

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Abstract (sommario):

A theoretical basis for quasi static determination of wheel—rail interaction forces using strain measures in the foot of the rail is given. Vlasov's theory for thin-walled beams is used in combination with continuous translational and rotational elastic supports based on smoothing out the stiffness of the rail sleepers. The smoothing out of the rotational elastic support has traditionally not been done. The use of this model is validated by the decay lengths of the problem and through finite element analysis. The finite element analysis is performed using discrete sleeper stiffness and Vlasov beam elements. The sensitivity of the measuring technique to parameter variations is illustrated and an example shows the simplicity of the proposed direct measuring technique.

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50

Suhr, Bettina, William A. Skipper, Roger Lewis e Klaus Six. "Sanded Wheel–Rail Contacts: Experiments on Sand Crushing Behaviour". Lubricants 11, n. 2 (20 gennaio 2023): 38. http://dx.doi.org/10.3390/lubricants11020038.

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Abstract (sommario):

In railway operation, the sanding process is used to overcome low adhesion conditions in the wheel–rail contact. In the literature, previously conducted research has been experimental, e.g., measuring adhesion coefficients (ACs) under different contact conditions (dry, wet, …) or applying different sands. Under dry conditions, sanding can reduce measured ACs, while under wet conditions different types of rail sand can leave ACs unchanged or increase adhesion. Despite active research, the physical mechanisms causing the change in ACs under sanded conditions are still poorly understood. A possible remedy is the development of advanced models of sanding including local effects. As a basis for such a model, this study presents experimental results concerning single grain crushing behaviour of two types of rail sand under dry and wet contact conditions. Firstly, initial breakage behaviour is investigated with focus on the particle fragments’ size and spread as only fragments within the running band are available to influence the AC during roll-over. Secondly, single grain crushing tests are conducted under realistic wheel–rail load showing the formation of solidified clusters of sand fragments, as well as their size and thickness. This information is important for understanding mechanisms and for future physics-based modelling of the sanding process in wheel–rail contacts.

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