Letteratura scientifica selezionata sul tema "STRESS ANALYSIS OF RAIL WHEEL"
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Articoli di riviste sul tema "STRESS ANALYSIS OF RAIL WHEEL"
1
Zhang, Tie, Jun Zhang e Chuan Xi Sun. "The Profile Analysis of Wheels and Rails of Different Wear Stages for Heavy-Haul Wagons". Applied Mechanics and Materials 602-605 (agosto 2014): 291–94. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.291.
Testo completoAbstract (sommario):
A large number of wheel and rail profiles of different wear stages are tracked and measured using the wheel/rail profile admeasuring apparatus for DaTong-QinHuangdao heavy-haul line. The finite element method (FEM) models and dynamic models of the contact between wheels and rails are both established for two working conditions (i.e., straight line and curve line). In addition, the corresponding parameters and indexes are obtained through the simulation and calculation. The results show that the maximum equivalent stress for the wheel profile of type II is lower than those of wheel profiles in other stages for the straight and curve lines. Its contact stress distribution is more uniform than others. The dynamics indexes including stationarity and stability of the standard wheel profiles ( i.e. LM) are the best. The indexes are gradually reduced along with the abrasion of wheel profiles. When passing the curve, the dynamics indexes of wheel profiles in each stage are reached the evaluation standard. The abrasion rate of wheels and rails can be reduced relatively when wheels are matched with the worn rails in the stable stage.
2
Ma, He, Jun Zhang e Xiu Juan Zhang. "The Calculation and Analysis for the Independent Wheels of Tramcar". Applied Mechanics and Materials 577 (luglio 2014): 297–300. http://dx.doi.org/10.4028/www.scientific.net/amm.577.297.
Testo completoAbstract (sommario):
The wheel/rail profiles in different wear stages are measured using the apparatus of wheel-rail profile. The 3D elastic-plastic FEM contact models are established for the straight line and curves, in which attack angle is considered. Contact problems between the wheels in different wear stages and the worn rail are studied. Contact area, normal contact force, and equivalent Von Mises stress of different cases are analyzed. The obtained results show that the maximum equivalent Von Mises stress reduces and tends to be steady with the independent wheel wearing. Widening the track gauge can have an influence on the variation of wheel wear positions and the wear rules between wheel and rail. When the wheel with a certain attack angle contacts with rail, the maximum equivalent Von Mises stress appears at the contact region between the flange and rail side. The influence of attack angle on the wear between the wheel and rail is quite serious. It is very important to do the research for the further optimization and design of the wheel/rail profiles.
3
Milošević, Miloš, Aleksandar Miltenović, Milan Banić e Miša Tomić. "DETERMINATION OF RESIDUAL STRESS IN THE RAIL WHEEL DURING QUENCHING PROCESS BY FEM SIMULATION". Facta Universitatis, Series: Mechanical Engineering 15, n. 3 (9 dicembre 2017): 413. http://dx.doi.org/10.22190/fume170206029m.
Testo completoAbstract (sommario):
Residual stresses of the rail wheels are influenced by heat treatment during the manufacturing process. The quenching process during the manufacturing results in the residual stresses within the rail wheel that may be dangerous for the rail wheel during its operation. Determination of the residual stress in the rail wheel is important for understanding the damage mechanisms and their influence on the proper work of rail wheels. This paper presents a method for determining the residual stresses in the rail wheel during the quenching process by using the directly coupled thermal-structural analysis in ANSYS software.
4
Liu, Kai, e Lin Jing. "A finite element analysis-based study on the dynamic wheel–rail contact behaviour caused by wheel polygonization". Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 234, n. 10 (4 dicembre 2019): 1285–98. http://dx.doi.org/10.1177/0954409719891549.
Testo completoAbstract (sommario):
In this study, an explicit finite element analysis method was adopted to investigate the wheel–rail impact response generated by wheel polygonization, using a three-dimensional wheel–rail rolling contact finite element model. In this model, the infrastructure below the rails and the stiffness and damping of the sleeper supports were considered. Then, the characteristics of the wheel–rail contact zone, the stress/strain state and the wheel–rail impact force of the polygonal wheel–rail system were presented and discussed and were compared with those of the ideally perfect wheel–rail system. A parametrical study was then carried out to examine the influences of train speed and the polygonal order of the wheel on the wheel–rail impact response. The finite element analysis results revealed that the vertical wheel–rail impact force induced by wheel polygonization is related to the wheel radial deviation; the maximum contact force, stress and strain are all elevated with the increase of the order of the polygonal wheel, which suggested that the wheel should be repaired when it is in the initial lower order polygonal state. These findings can provide some theoretical and technical support for the optimal design of the wheel–rail system and the safe operation of high-speed trains.
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Kumar, S., e S. P. Singh. "Rail Head Geometry, Rail Rolling and Wheel-Rail Contact Tilting Analysis for Heavy Axle Loads". Journal of Engineering for Industry 111, n. 4 (1 novembre 1989): 375–81. http://dx.doi.org/10.1115/1.3188775.
Testo completoAbstract (sommario):
This paper presents analytical considerations which are important to design a rail head for reducing rail damage due to heavy axle loads. There are two important parameters of design of rail crown: (1) the wheel tread rail crown contact stress and (2) the contact tilt angle called the β angle. Contact should not be allowed to move out of the rail crown. Analysis of lateral oscillations of new and worn wheel sets shows that they do not impose an engineering constraint on the choice of rail crown radius. Rail rolling on curves due to lateral creepage forces is however of great importance in rail loading and stresses. The point of contact location is significantly affected by such roll. For the two commonly used rails, 132 RE and 136 RE, this roll results in the contact moving to the part of the rail head with radius of 1 1/4 in. Such movement of the contact also develops rapidly when hollowed worn wheels roll on flattened worn rails. It is pointed out that this condition results in forces higher than the wheel load and stresses more than twice the value developed when the contact is within the rail crown and that this is most likely responsible for many of the rail failure problems including cracking, shelling, and fractures. A design analysis of rail crown including Hertzian contact and rail twist considerations shows that none of the three current rails analyzed satisfy the criteria developed for good rail head design. A suitable ellipitical crown should prove better. Finally a systems approach to rail wheel interaction with a number of design recommendations is given.
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Kumar, S., e S. P. Singh. "Heavy Axle Load Wheel-Rail Contact Stresses and Their Tread-Crown Curvature Relationships". Journal of Engineering for Industry 111, n. 4 (1 novembre 1989): 382–87. http://dx.doi.org/10.1115/1.3188776.
Testo completoAbstract (sommario):
This paper presents a theoretical/design analysis of wheel-rail contact stresses and geometries for U.S. freight cars of 70, 95, 100, and 125 ton freight capacities operating on various crown rails. After discussing various types of rail stresses, it is pointed out that the contact stresses are the major factor and the only parameter that enables a designer to improve or optimize the rail life and performance. In order to determine the most suitable diameters for the heavier cars, an engineering lower bound analysis of the contact has been completed. It uses in a two-dimensional Hertzian analysis, the field information of well worn-out wheel and rail contacts which are almost rectangular and of 1 in. width. The lower engineering bound values of maximum normal contact stresses for the 100 and 125 ton cars using wheels of diameters from 33 to 42 in. are given. This stress for the current 100 ton car with 36 in. diameter wheels is 98.35 ksi. To approach this value for the 125 ton car it is necessary to use 42 in. diameter wheels which is strongly recommended for the U.S. railroads. A Hertz theory based analysis of the contact stresses with varying wheel diameter, tread profile radius and rail crown radius for the 70, 95, 100, and 125 ton cars has been presented. Using the field information that the difference in radii of curvature of worn wheel and rail is approximately 5 in., choice of radii of rail and wheel profile curvatures is made so that the design radii difference is always 5 in. or more. Wheel diameter and wheel profile radius ranges used for this analysis were 33 to 44 in. and 15 to 35 in., respectively. The rail crown radius range was 10 to 30 in. It was concluded that a rail crown radius of 15 to 20 in. and wheel tread profile radius of 22 to 30 in. are good initial ranges for further analysis of design.
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Axinte, Tiberiu. "Analysis of Rails of a Ferry Boat under Wheels Contact Loading". Advanced Materials Research 837 (novembre 2013): 739–44. http://dx.doi.org/10.4028/www.scientific.net/amr.837.739.
Testo completoAbstract (sommario):
The paper presents the effect of the discontinuity of the rails of a ferry boat and the presence of lower modulus insulation material at the gap to the variations of stresses in the insulated rail. The analysis consists of a three-dimensional wheel rail contact model based on the finite element method. One of the results shows that the maximum stress occurs in the subsurface of the railhead of the ferry boat. The ratio of the elastic modulus of the railhead and insulation material is found to alter the levels of stress concentration. Numerical result indicates that a higher elastic modulus insulating material can reduce the stress concentration in the railhead but will generate higher stresses in the insulation material, leading to earlier failure of the insulation material. A general subsurface crack propagation analysis methodology is used for the wheel and rail rolling contact. The fatigue damage in the wheel is calculated using a previously developed mixed-mode fatigue crack propagation model. The advantages of the proposed methodology are that it can accurately represent the contact stress of complex mechanical components and can consider the effect of loading non-proportionality. The effects of wheel diameter, vertical loading amplitude, initial crack size, location and orientation on stress intensity factor range are investigated using the proposed model. The prediction results of the proposed methodology are compared with in field observations. The contact elements were used to stimulate the interaction between a wheel and a railhead. Variations in contact stress fields at various locations of the rail are sensitive to the contact distance. The location of the maximum von Mises stress was shifted to the contact surface as the contact point moves close to the rail end. A higher stress, larger deflection and significant plastic deformation occurring at the rail from ferry boat may lead to deterioration at the rail end.
8
Gu, Shao Jie, Xin Wen Yang e Song Liang Lian. "An Analysis of 3-D Wheel-Rail Contact Stress under Heavy Axle Load Using Non-Linear Finite Element Method". Applied Mechanics and Materials 638-640 (settembre 2014): 1128–34. http://dx.doi.org/10.4028/www.scientific.net/amm.638-640.1128.
Testo completoAbstract (sommario):
Wheel-rail contact stress is foundation of the relationship between wheel and rail, and also an important basis for investigating further wear, surface damage and other problems of wheel and rail system. A three dimension elastic-plastic wheel/rail contact model is established using non-linear finite element method. The changes of wheel/rail normal contact stress, Mises stress and elastic-plastic deformations are analyzed under different conditions in heavy haul railway. A method is provided for a foundation of the future study of wheel-rail contact wear, fatigue and cracks germination and development in this paper.
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Akeel, N. A., M. A. Aziman, Zainuddin Sajuri, Ahmad Kamal Ariffin e A. W. Ikhsan. "Identification of Damages and Stress Analysis of Rail/Wheel Rolling Contact Region". Key Engineering Materials 462-463 (gennaio 2011): 1152–57. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.1152.
Testo completoAbstract (sommario):
This paper presents the identification of damages and stress analysis of rail/wheel rolling contact region. The railhead surface of used rail track was investigated to identify damages and the hardness of the rail/wheel contact area was measured. Finite element method FEM code, ANSYS was used to determine the stress distribution at vicinity of rail/wheel contact area. The results showed that the hardness increased on the contact area between rail and wheel due to repeated rolling contact of rail and wheel surface. Severe damages and cracks were observed on the railhead surface and in the cross section of the rail at the contact region. The FEM simulation showed that the highest stress distribution regions were matched with the area of severely damage and high hardness obtained from the observation and experimental results.
10
Wu, Feng Qi, Jin Zhang e Wen Qing Yao. "Crane Wheel-Rail Contact Stresses Research Based on Experimental Test and Finite Element Analysis". Applied Mechanics and Materials 496-500 (gennaio 2014): 662–65. http://dx.doi.org/10.4028/www.scientific.net/amm.496-500.662.
Testo completoAbstract (sommario):
The wheel-rail contact is a boundary condition highly nonlinear complex problem, which need to accurately track the wheel-rail movement and the interaction contact stress between wheel-rail before and after the occurrence of wheel-rail contact, nonlinear contact stress of wheel-rail is analyzed through the contrast of finite element analysis and the actual detection, the experimental and theoretical calculation results show the compliance of the finite element model of wheel-rail, at the same time also point out some differences of theoretical calculation and actual manufacturing, which establish the theoretical and experimental foundation for the advanced research movement friction etc..
Tesi sul tema "STRESS ANALYSIS OF RAIL WHEEL"
1
Bian, Jian. "Ultimate flexural limit states analysis of prestressed concrete sleeper". Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/63660/1/Jian_Bian_Thesis.pdf.
Testo completoAbstract (sommario):
Railway is one of the most important, reliable and widely used means of transportation, carrying freight, passengers, minerals, grains, etc. Thus, research on railway tracks is extremely important for the development of railway engineering and technologies. The safe operation of a railway track is based on the railway track structure that includes rails, fasteners, pads, sleepers, ballast, subballast and formation. Sleepers are very important components of the entire structure and may be made of timber, concrete, steel or synthetic materials. Concrete sleepers were first installed around the middle of last century and currently are installed in great numbers around the world. Consequently, the design of concrete sleepers has a direct impact on the safe operation of railways.
The "permissible stress" method is currently most commonly used to design sleepers. However, the permissible stress principle does not consider the ultimate strength of materials, probabilities of actual loads, and the risks associated with failure, all of which could lead to the conclusion of cost-ineffectiveness and over design of current prestressed concrete sleepers. Recently the limit states design method, which appeared in the last century and has been already applied in the design of buildings, bridges, etc, is proposed as a better method for the design of prestressed concrete sleepers. The limit states design has significant advantages compared to the permissible stress design, such as the utilisation of the full strength of the member, and a rational analysis of the probabilities related to sleeper strength and applied loads.
This research aims to apply the ultimate limit states design to the prestressed concrete sleeper, namely to obtain the load factors of both static and dynamic loads for the ultimate limit states design equations. However, the sleepers in rail tracks require different safety levels for different types of tracks, which mean the different types of tracks have different load factors of limit states design equations. Therefore, the core tasks of this research are to find the load factors of the static component and dynamic component of loads on track and the strength reduction factor of the sleeper bending strength for the ultimate limit states design equations for four main types of tracks, i.e., heavy haul, freight, medium speed passenger and high speed passenger tracks.
To find those factors, the multiple samples of static loads, dynamic loads and their distributions are needed. In the four types of tracks, the heavy haul track has the measured data from Braeside Line (A heavy haul line in Central Queensland), and the distributions of both static and dynamic loads can be found from these data. The other three types of tracks have no measured data from sites and the experimental data are hardly available. In order to generate the data samples and obtain their distributions, the computer based simulations were employed and assumed the wheel-track impacts as induced by different sizes of wheel flats. A valid simulation package named DTrack was firstly employed to generate the dynamic loads for the freight and medium speed passenger tracks. However, DTrack is only valid for the tracks which carry low or medium speed vehicles. Therefore, a 3-D finite element (FE) model was then established for the wheel-track impact analysis of the high speed track. This FE model has been validated by comparing its simulation results with the DTrack simulation results, and with the results from traditional theoretical calculations based on the case of heavy haul track. Furthermore, the dynamic load data of the high speed track were obtained from the FE model and the distributions of both static and dynamic loads were extracted accordingly. All derived distributions of loads were fitted by appropriate functions. Through extrapolating those distributions, the important parameters of distributions for the static load induced sleeper bending moment and the extreme wheel-rail impact force induced sleeper dynamic bending moments and finally, the load factors, were obtained. Eventually, the load factors were obtained by the limit states design calibration based on reliability analyses with the derived distributions. After that, a sensitivity analysis was performed and the reliability of the achieved limit states design equations was confirmed. It has been found that the limit states design can be effectively applied to railway concrete sleepers.
This research significantly contributes to railway engineering and the track safety area. It helps to decrease the failure and risks of track structure and accidents; better determines the load range for existing sleepers in track; better rates the strength of concrete sleepers to support bigger impact and loads on railway track; increases the reliability of the concrete sleepers and hugely saves investments on railway industries.
Based on this research, many other bodies of research can be promoted in the future. Firstly, it has been found that the 3-D FE model is suitable for the study of track loadings and track structure vibrations. Secondly, the equations for serviceability and damageability limit states can be developed based on the concepts of limit states design equations of concrete sleepers obtained in this research, which are for the ultimate limit states.
2
Telliskivi, Tanel. "Wheel-rail Interaction Analysis". Doctoral thesis, KTH, Machine Design, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3532.
Testo completoAbstract (sommario):
A general approach to numerically simulating wear in rollingand sliding contacts is presented in this thesis. A simulationscheme is developed that calculates the wear at a detailedlevel. The removal of material follows Archards wear law,which states that the reduction of volume is linearlyproportional to the sliding distance, the normal load and thewear coefficient. The target application is the wheel-railcontact.
Careful attention is paid to stress properties in the normaldirection of the contact. A Winkler method is used to calculatethe normal pressure. The model is calibrated either withresults from Finite Element simulations (which can include aplastic material model) or a linear-elastic contact model. Thetangential tractions and the sliding distances are calculatedusing a method that incorporates the effect of rigid bodymotion and tangential deformations in the contact zone.Kalkers Fastsim code is used to validate the tangentialcalculation method. Results of three different sorts ofexperiments (full-scale, pin-on-disc and disc-on-disc) wereused to establish the wear and friction coefficients underdifferent operating conditions.
The experimental results show that the sliding velocity andcontact pressure in the contact situation strongly influencethe wear coefficient. For the disc-on-disc simulation, therewas good agreement between experimental results and thesimulation in terms of wear and rolling friction underdifferent operating conditions. Good agreement was alsoobtained in regard to form change of the rollers. In thefull-scale simulations, a two-point contact was analysed wherethe differences between the contacts on rail-head to wheeltread and rail edge to wheel flange can be attributed primarilyto the relative velocity differences in regard to bothmagnitude and direction. Good qualitative agreement was foundbetween the simulated wear rate and the full-scale test resultsat different contact conditions.
Keywords:railway rail, disc-on-disc, pin-on-disc,Archard, wear simulation, Winkler, rolling, sliding
3
Zhan, Yun, e 詹云. "Finite element analysis of vibration excited by rail-wheel interaction". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/208053.
Testo completo
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BOZZONE, MICHELANGELO. "Dynamic analysis of railway systems using computationally efficient wheel-rail contact models". Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2010. http://hdl.handle.net/2108/1332.
Testo completoAbstract (sommario):
La presente tesi descrive l’analisi dinamica condotta su un sistema ferroviario quale una sala , un carrello e un vagone.
La posizione dei punti di contatto tra la ruota e la rotaia è determinata tramite lo studio delle posizioni di equilibrio della sala poggiata su una coppia di rotaie. L’analisi permette anche di determinare la normale e le curvature principali delle superfici della ruota e della rotaia nei punti di contatto.
Al fine di ridurre i tempi di calcolo, i risultati dello studio sono stati memorizzati in una tabella di calcolo usata per l’analisi dinamica della sala, del carrello e del vagone. E’ stata condotta l’analisi dinamica di un carrello formato da due sale e dal telaio. Il telaio è collegato alle sale per mezzo del sistema di sospensione primario che agisce lungo le tre direzioni principali: longitudinale, trasversale e verticale. Il carrello può muoversi lungo un tracciato rettilineo o curvilineo con o senza angolo di sopralzo e in presenza o assenza di una perturbazione trasversale iniziale. Le caratteristiche di contatto sono determinate per mezzo della tabella di calcolo. Per ridurre di tempi di calcolo è stato sviluppato un nuovo metodo per l’interpolazione delle tabella di calcolo. Per l’integrazione delle equazioni differenziali del moto sono stati testati due metodi che sono stati confrontati con i risultati forniti dal software multibody Simpack. E’ stato condotto uno studio in prossimità delle condizioni critiche del carrello sia su un tracciato rettilineo che curvilineo. La velocità critica è stata determinata attraverso l’analisi del moto di serpeggio usando due metodi. La velocità critica, le forze di contatto e i limiti di deragliamento sono stati determinati in diverse condizioni di carico e di tracciato. E’ stata inoltre analizzata l’influenza della rigidezza longitudinale del sistema di sospensione primario e secondario sulle condizioni critiche del carrello e del vagone sia su un tracciato rettilineo che curvilineo.The present thesis describes an investigation on the railway system motion like a wheel-set, a bogie or a wagon. Through the search of equilibrium configurations, the positions of contact points between rails and wheels are first located. The detection methods allow also the definition of the normal vectors to rail and wheel surfaces and the principal curvatures at contact points. To reduce computing time the results are stored in a lookup table that can be used for dynamic analysis of wheel-sets, bogie or wagon. A dynamic analysis has been performed on a bogie composed of two wheel-sets and a frame. The bogie frame is joined to the wheel-sets by means of a primary suspension system, acting on the three principal directions, i.e. longitudinal, transverse and vertical. The bogie moves along rails following its variable path. In particular, the dynamic analysis investigates the bogie behaviour in both straight and curved paths, with or without an initial perturbation and a super-elevation angle. Imposing an initial transverse disturbance, the hunting motion is observed and the critical speed value estimated. The contact characteristics have been determined by means of the lookup table. In order to minimize cpu-time, a new method for the interpolation of the lookup table entries has been developed. Finally, two different methods for the integration of the differential equations have been tested and comparisons with the results obtained by Simpack-rail multibody software are discussed. The railway systems have been analyzed in proximity of their critical conditions both in straight and curved tracks. The critical speed is estimated through the rise up of hunting motion. The critical speed, the contact forces in the critical conditions and the derailment limits are determined under different load conditions and track paths; two methods are used for its determination. The influence of the longitudinal suspension stiffness of the primary and secondary suspension systems on the critical conditions of the bogie and wagon are deduced for straight and curved track type.
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Rinaldi, Elisa. "3D Finite Element Analysis of Wheel/Rail normal contact problem using ANSYS software". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
Cerca il testo completoAbstract (sommario):
La meccanica del contatto fra ruota ferroviaria e rotaia, è una delle più importanti aree di studio nell’Ingegneria Ferroviaria. Ad oggi, un vasto numero di formulazioni analitiche sono state proposte dai ricercatori, con lo scopo di valutare i parametri di contatto tra ruota e rotaia ed arrivare ad una descrizione affidabile delle forze che agiscono nell’area di contatto. Comunque, solo alcuni dei metodi disponibili permettono di considerare, nelle loro elaborazioni, la reale geometria di contatto tra ruota e rotaia o la non linearità delle proprietà dei materiali impiegati. Un’alternativa ai metodi analitici per descrivere la fisica del contatto tra ruota e rotaia e di fare uso di tecniche computazionali numeriche quale l’Analisi agli Elementi Finiti (FEA – Finite Element Analysis). Il vantaggio di questo metodo è dato dalla possibilità di poter modellare complesse geometrie che permettono di simulare più accuratamente il contatto tra ruota e rotaia e determinare l’ampiezza degli stress e la loro distribuzione, oltre alla dimensione e forma dell’area di contatto.
Per questa ragione, un modello agli Elementi Finiti tridimensionale della ruota ferroviaria e della rotaia è stato creato utilizzando Ansys Parametric Design Language di ANSYS per studiare il problema di contatto normale. Per verificare l’accuratezza dei risultati forniti dal modello, questo è stato validato in confronto alla teoria di Hertz sul contatto elastico. Questa teoria rappresenta la base sulla quale la maggior parte dei modelli computazionali vengono sviluppati.
Il principali scopi di questa tesi sono quindi di studiare i problemi del contatto tra ruota e rotaia e di valutare l’influenza dei parametri operativi quali il coefficiente di frizione, lo spostamento laterale della sala montata e l’inclinazione della rotaia sul piano orizzontale, sulla fisica del contatto.
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White, Ben. "Using tribo-chemistry analysis to understand low adhesion in the wheel-rail contact". Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/21007/.
Testo completoAbstract (sommario):
Low adhesion between wheel and rail is a recurrent problem for the rail industry. Low adhesion can lead to wheel slides and slips during acceleration and deceleration, which can cause large amounts of damage to the wheel and rail as well as causing safety issues and delays if a train cannot accelerate or decelerate when necessary. Adhesion in the wheel-rail contact is affected by the third body layer which is present in the contact patch between wheel and rail. It is composed naturally from steel wear debris and iron oxides, but often contains other contaminants such as organic matter, ballast dust, soil and grease. Different environmental conditions such as temperature, precipitation and humidity change the properties of this third body layer and therefore change adhesion conditions on the railway. Low adhesion has been well documented throughout the autumn season due to organic contamination, but also takes place throughout the year when no visible contamination is seen on the railhead, known as the “wet-rail” phenomenon. It is thought to occur when there are low levels of water on the railhead, formed by dew, mist or light rain, rather than heavy rain. The conditions and mechanisms that cause the phenomenon are not fully understood. Low adhesion does not occur very often and under what is likely to be a narrow window of conditions, which means that it can be difficult to simulate and study. The aim of this work was to use a combination of tribology and chemistry to better understand the cause of low adhesion throughout the year, known as the wet-rail phenomenon. It investigated low adhesion conditions that occur all year round, initially focusing on the role of iron oxide in low adhesion as it has previously been hypothesised that oxides could play a major role in the wet-rail phenomenon. Testing was carried out over a range of conditions on three different tribological test rigs to attempt to simulate low adhesion due to the wet-rail phenomenon, which produced valuable information about the causes of low adhesion. It was found that, under certain conditions, a combination of iron oxides and water could cause low adhesion in a simulated wheel-rail contact. Test methods were designed to simulate the wet-rail phenomenon, which can be used as a platform to better understand the causes of low adhesion and to test future mitigation methods.
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Dareeju, Biyanvilage. "Performance evaluation of unsaturated rail track foundations under cyclic moving wheel load". Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/102697/4/Biyanvilage%2520Sampath%2520Sri%2520Sameera_Dareeju_Thesis.pdf.
Testo completoAbstract (sommario):
This thesis developed an alternative laboratory element testing method to evaluate the response of the unsaturated soils of rail track foundations under repeated moving wheel loadings. The novel laboratory testing method is more capable of producing the realistic strength-deformation characteristics of the unsaturated soils with the effects of principal stress axis rotation (PSAR), which can be used to redesign the conservative rail track guidelines.
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Lee, Hyunwook. "A Polynomial Chaos Approach for Stochastic Modeling of Dynamic Wheel-Rail Friction". Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77195.
Testo completoAbstract (sommario):
Accurate estimation of the coefficient of friction (CoF) is essential to accurately modeling railroad dynamics, reducing maintenance costs, and increasing safety factors in rail operations. The assumption of a constant CoF is popularly used in simulation studies for ease of implementation, however many evidences demonstrated that CoF depends on various dynamic parameters and instantaneous conditions. In the real world, accurately estimating the CoF is difficult due to effects of various uncertain parameters, such as wheel and rail materials, rail roughness, contact patch, and so on. In this study, the newly developed 3-D nonlinear CoF model for the dry rail condition is introduced and the CoF variation is tested using this model with dynamic parameters estimated from the wheel-rail simulation model. In order to account for uncertain parameters, a stochastic analysis using the polynomial chaos (poly-chaos) theory is performed using the CoF and wheel-rail dynamics models.
The wheel-rail system at a right traction wheel is modeled as a mass-spring-damper system to simulate the basic wheel-rail dynamics and the CoF variation. The wheel-rail model accounts for wheel-rail contact, creepage effect, and creep force, among others. Simulations are performed at train speed of 20 m/s for 4 sec using rail roughness as a unique excitation source. The dynamic simulation has been performed for the deterministic model and for the stochastic model. The dynamics results of the deterministic model provide the starting point for the uncertainty analysis. Six uncertain parameters have been studied with an assumption of 50% uncertainty, intentionally imposed for testing extreme conditions. These parameters are: the maximum amplitude of rail roughness (MARR), the wheel lateral displacement, the track stiffness and damping coefficient, the sleeper distance, and semi-elliptical contact lengths. A symmetric beta distribution is assumed for these six uncertain parameters. The PDF of the CoF has been obtained for each uncertain parameter study, for combinations of two different uncertain parameters, and also for combinations of three different uncertain parameters.
The results from the deterministic model show acceptable vibration results for the body, the wheel, and the rail. The introduced CoF model demonstrates the nonlinear variation of the total CoF, the stick component, and the slip component. In addition, it captures the maximum CoF value (initial peak) successfully. The stochastic analysis results show that the total CoF PDF before 1 sec is dominantly affected by the stick phenomenon, while the slip dominantly influences the total CoF PDF after 1 sec. Although a symmetric distribution has been used for the uncertain parameters considered, the uncertainty in the response obtained displayed a skewed distribution for some of the situations investigated. The CoF PDFs obtained from simulations with combinations of two and three uncertain parameters have wider PDF ranges than those obtained for only one uncertain parameter.
FFT analysis using the rail displacement has been performed for the qualitative validation of the stochastic simulation result due to the absence of the experimental data. The FFT analysis of the deterministic rail displacement and of the stochastic rail displacement with uncertainties demonstrates consistent trends commensurate with loss of tractive efficiency, such as the bandwidth broadening, peak frequency shifts, and side band occurrence. Thus, the FFT analysis validates qualitatively that the stochastic modeling with various uncertainties is well executed and is reflecting observable, real-world results.
In conclusions, the development of an effective model which helps to understand the nonlinear nature of wheel-rail friction is critical to the progress of railroad component technology and rail safety. In the real world, accurate estimation of the CoF at the wheel-rail interface is very difficult since it is influenced by several uncertain parameters as illustrated in this study. Using the deterministic CoF value can cause underestimation or overestimation of CoF values leading to inaccurate decisions in the design of the wheel-rail system. Thus, the possible PDF ranges of the CoF according to key uncertain parameters must be considered in the design of the wheel-rail system.Ph. D.
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Zong, Nannan. "Development of optimal designs of insulated rail joints". Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/61125/1/Nannan_Zong_Thesis.pdf.
Testo completoAbstract (sommario):
Proper functioning of Insulated Rail Joints (IRJs) is essential for the safe operation of the railway signalling systems and broken rail identification circuitries. The Conventional IRJ (CIRJ) resembles structural butt joints consisting of two pieces of rails connected together through two joint bars on either side of their web and the assembly is held together through pre-tensioned bolts. As the IRJs should maintain electrical insulation between the two rails, a gap between the rail ends must be retained at all times and all metal contacting surfaces should be electrically isolated from each other using non-conductive material. At the gap, the rail ends lose longitudinal continuity and hence the vertical sections of the rail ends are often severely damaged, especially at the railhead, due to the passage of wheels compared to other continuously welded rail sections.
Fundamentally, the reason for the severe damage can be related to the singularities of the wheel-rail contact pressure and the railhead stress. No new generation designs that have emerged in the market to date have focussed on this fundamental; they only have provided attention to either the higher strength materials or the thickness of the sections of various components of the IRJs. In this thesis a novel method of shape optimisation of the railhead is developed to eliminate the pressure and stress singularities through changes to the original sharp corner shaped railhead into an arc profile in the longitudinal direction. The optimal shape of the longitudinal railhead profile has been determined using three nongradient methods in search of accuracy and efficiency: (1) Grid Search Method; (2) Genetic Algorithm Method and (3) Hybrid Genetic Algorithm Method. All these methods have been coupled with a parametric finite element formulation for the evaluation of the objective function for each iteration or generation depending on the search algorithm employed.
The optimal shape derived from these optimisation methods is termed as Stress Minimised Railhead (SMRH) in this thesis. This optimal SMRH design has exhibited significantly reduced stress concentration that remains well below the yield strength of the head hardened rail steels and has shifted the stress concentration location away from the critical zone of the railhead end. The reduction in the magnitude and the relocation of the stress concentration in the SMRH design has been validated through a full scale wheel – railhead interaction test rig; Railhead strains under the loaded wheels have been recorded using a non-contact digital image correlation method. Experimental study has confirmed the accuracy of the numerical predications.
Although the SMRH shaped IRJs eliminate stress singularities, they can still fail due to joint bar or bolt hole cracking; therefore, another conceptual design, termed as Embedded IRJ (EIRJ) in this thesis, with no joint bars and pre-tensioned bolts has been developed using a multi-objective optimisation formulation based on the coupled genetic algorithm – parametric finite element method. To achieve the required structural stiffness for the safe passage of the loaded wheels, the rails were embedded into the concrete of the post tensioned sleepers; the optimal solutions for the design of the EIRJ is shown to simplify the design through the elimination of the complex interactions and failure modes of the various structural components of the CIRJ.
The practical applicability of the optimal shapes SMRH and EIRJ is demonstrated through two illustrative examples, termed as improved designs (IMD1 & IMD2) in this thesis; IMD1 is a combination of the CIRJ and the SMRH designs, whilst IMD2 is a combination of the EIRJ and SMRH designs. These two improved designs have been simulated for two key operating (speed and wagon load) and design (wheel diameter) parameters that affect the wheel-rail contact; the effect of these parameters has been found to be negligible to the performance of the two improved designs and the improved designs are in turn found far superior to the current designs of the CIRJs in terms of stress singularities and deformation under the passage of the loaded wheels. Therefore, these improved designs are expected to provide longer service life in relation to the CIRJs.
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Hopkins, Brad Michael. "A Wavelet-Based Rail Surface Defect Prediction and Detection Algorithm". Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/77351.
Testo completoAbstract (sommario):
Early detection of rail defects is necessary for preventing derailments and costly damage to the train and railway infrastructure. A rail surface flaw can quickly propagate from a small fracture to a broken rail after only a few train cars have passed over it. Rail defect detection is typically performed by using an instrumented car or a separate railway monitoring vehicle. Rail surface irregularities can be measured using accelerometers mounted to the bogie side frames or wheel axles. Typical signal processing algorithms for detecting defects within a vertical acceleration signal use a simple thresholding routine that considers only the amplitude of the signal. As a result, rail surface defects that produce low amplitude acceleration signatures may not be detected, and special track components that produce high amplitude acceleration signatures may be flagged as defects.
The focus of this research is to develop an intelligent signal processing algorithm capable of detecting and classifying various rail surface irregularities, including defects and special track components. Three algorithms are proposed and validated using data collected from an instrumented freight car. For the first two algorithms, one uses a windowed Fourier Transform while the other uses the Wavelet Transform for feature extraction. Both of these algorithms use an artificial neural network for feature classification. The third algorithm uses the Wavelet Transform to perform a regularity analysis on the signal. The algorithms are validated with the collected data and shown to out-perform the threshold-based algorithm for the same data set.
Proper training of the defect detection algorithm requires a large data set consisting of operating conditions and physical parameters. To generate this training data, a dynamic wheel-rail interaction model was developed that relates defect geometry to the side frame vertical acceleration signature. The model was generated by using combined systems dynamic modeling, and the system was solved with a developed combined lumped and distributed parameter system numerical approximation. The broken rail model was validated with real data collected from an instrumented freight car. The model was then used to train and validate the defect detection methodologies for various train and rail physical parameters and operating conditions.Ph. D.
Capitoli di libri sul tema "STRESS ANALYSIS OF RAIL WHEEL"
1
Guerrieri, Marco. "Wheel-Rail Interaction and Derailment Analysis". In Springer Tracts in Civil Engineering, 79–87. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-24030-0_4.
Testo completo
2
Bogacz, R. "On residual stresses in corrugated rails and wheel/rail interaction". In Residual Stress in Rails, 87–100. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-1787-6_5.
Testo completo
3
Kalousek, J. "Experimental Tribo-Analysis of Rail/Wheel Interface". In Rail Quality and Maintenance for Modern Railway Operation, 225–38. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-015-8151-6_18.
Testo completo
4
True, Hans. "Dynamics of Railway Vehicles and Rail/Wheel Contact". In Dynamical Analysis of Vehicle Systems, 75–128. Vienna: Springer Vienna, 2009. http://dx.doi.org/10.1007/978-3-211-76666-8_2.
Testo completo
5
Bower, A. F., e K. L. Johnson. "Shakedown, Residual Stress and Plastic Flow in Repeated Wheel-Rail Contact". In Rail Quality and Maintenance for Modern Railway Operation, 239–49. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-015-8151-6_19.
Testo completo
6
Wild, Eric, e Walter Reimers. "Residual Stress and Microstructure in the Rail/Wheel Contact Zone of a Worn Railway Wheel". In Materials Science Forum, 911–16. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-414-6.911.
Testo completo
7
Sehitoglu, Huseyin, e Y. Roger Jiang. "Residual Stress Analysis in Rolling Contact". In Rail Quality and Maintenance for Modern Railway Operation, 349–58. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-015-8151-6_28.
Testo completo
8
Decroos, Kris, Jonathan Ceulemans, Bert Stallaert e Tom Vanhonacker. "Wheel-Rail Contact Analysis with Emphasis on Wear (Measurements/Simulation)". In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 259–66. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70289-2_26.
Testo completo
9
Olzak, Mirosław, Jacek Stupnicki e Ryszard Wójcik. "Numerical Analysis of 3D Cracks Propagating in the Rail-Wheel Contact Zone". In Rail Quality and Maintenance for Modern Railway Operation, 385–95. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-015-8151-6_31.
Testo completo
10
Ronasi, Hamed, Håkan Johansson e Fredrik Larsson. "Identification of Wheel-Rail Contact Forces Based on Strain Measurement and Finite Element Model of the Rolling Wheel". In Topics in Modal Analysis II, Volume 6, 169–77. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-2419-2_15.
Testo completoAtti di convegni sul tema "STRESS ANALYSIS OF RAIL WHEEL"
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Euston, Todd L., Allan M. Zarembski, Christopher M. Hartsough e Joseph W. Palese. "Analysis of Wheel-Rail Contact Stresses Through a Turnout". In 2012 Joint Rail Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/jrc2012-74004.
Testo completoAbstract (sommario):
The turnout represents a complex component of the track structure that generates high levels of vertical and lateral dynamic forces. This in turn results in high levels of wheel/rail contact stress and corresponding high rates of track degradation, significantly greater than in conventional track. Furthermore, the location of these high contact stresses vary as a vehicle negotiates the turnout. This paper presents the results of a series of analyses and computer simulations developed to examine the wheel/rail contact behavior as a vehicle negotiates a turnout and to determine the location and magnitude of the associated wheel/rail contact stresses. These analyses include a procedure for aligning the wheelset profile to the rail profile pair, based on the actual rail profiles, as it varies through the turnout. Using the point-by-point alignment, the analyses then determine the location of the wheel/rail contact patch and then calculate the magnitude of the contact stress profile in that patch. The result is a map of the wheel/rail contact stress as a vehicle moves through the turnout.
2
Sura, Venkata S., e Sankaran Mahadevan. "Estimation of Residual Stress Distribution in Railroad Wheels". In 2009 Joint Rail Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/jrc2009-63011.
Testo completoAbstract (sommario):
Residual stresses in railroad wheel rims significantly affect the wheel failure life; therefore, it is important to consider residual stresses for wheel failure analysis. In this paper, an advanced computational methodology is developed to estimate residual stresses developed during both the manufacturing process and under service conditions. To estimate the residual stresses in the wheel, three-dimensional decoupled thermal-structural analyses are performed. To simulate the manufacturing process, thermal analysis is performed with convection boundary conditions on the wheel surfaces. The temperature distributions obtained from this thermal analysis are input as loads for structural analysis. The results represent as-manufactured residual stresses. To simulate the thermal brake loading under service conditions, thermal analysis is performed using a heat flux boundary condition on the tread surface. Structural analysis is performed, including the estimated as-manufactured residual stress as initial stress, and using the temperature distributions obtained from thermal analysis of the on-tread braking. The resultant stresses represent the complex combination of residual stresses developed during both the manufacturing process and on-tread braking. The computed results are compared with the experimental data obtained at TTCI and the values reported in the literature.
3
Stone, Daniel H., e Scott M. Cummings. "Effect of Residual Stress, Temperature and Adhesion on Wheel Surface Fatigue Cracking". In ASME 2008 Rail Transportation Division Fall Technical Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/rtdf2008-74029.
Testo completoAbstract (sommario):
The Wheel Defect Prevention Research Consortium (WDPRC) conducted an analysis pertaining to the fatigue cracking of wheel treads by incorporating the effects of residual stresses, temperature, and wheel/rail contact stress. Laboratory fatigue tests were conducted on specimens of wheel tread material under a variety of conditions allowing the analysis to properly account for the residual stresses accumulated in normal operating conditions. Existing literature was used in the analysis in consideration of the effects of contact stress and residual stress relief. This project was performed to define a temperature range in which the life of an AAR Class C wheel is not shortened by premature fatigue and shelling. Wayside wheel thermal detectors are becoming more prevalent on North American railroads as a means of identifying trains, cars, and wheels with braking issues. Yet, from a wheel fatigue perspective, the acceptable maximum operating temperature remains loosely defined for AAR Class C wheels. It was found that residual compressive circumferential stresses play a key role in protecting a wheel tread from fatigue damage. Therefore, temperatures sufficient to relieve residual stresses are a potential problem from a wheel fatigue standpoint. Only the most rigorous braking scenarios can produce expected train average wheel temperatures approaching the level of concern for reduced fatigue life. However, the variation in wheel temperatures within individual cars and between cars can result in temperatures high enough to cause a reduction in wheel fatigue life.
4
Galbraith, Jay, George Ames e Scott Leister. "Consistent and Repeatable Property and Residual Stress Control in Forged and Heat Treated Railway Wheels". In 2011 Joint Rail Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/jrc2011-56089.
Testo completoAbstract (sommario):
Consistent process control of wheel hardness and residual stresses developed during heat treatment are particularly important considerations for service life and safety of railway wheels. This paper details the process controls strategically located throughout an integrated, fully automated heat treatment system that can heat treat up to 65 railway wheels per hour. New, innovative technology such as in-line temperature measurements that control key process steps, uniform wheel heating and cooling, and quench water temperature and pressure control have resulted in wheel hardness and residual stress values with less statistical variation than older, traditional heat treat methods. Automatic serial number tracking and temperature measurement allow for statistical analysis of heat treat processes. Two years after the commissioning of this $18M facility, the quality and productivity benefits realized are discussed.
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Lonsdale, Cameron, Thomas Rusin e Thomas Hay. "Research to Understand the Effects of Wheel Impact Loads on Wheel Stress Levels". In 2009 Joint Rail Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/jrc2009-63026.
Testo completoAbstract (sommario):
In recent years wheel impact loads have become a very important topic in the railroad industry due to operational and safety concerns. Much attention has been given to the level of condemnable wheel impact load as determined by wayside detection systems, and to the root causes of tread defects that lead to these wheel impacts. This paper describes physical testing of a wheelset in an instrumented drop hammer system to examine the effects of impact loading on resultant stress levels at various locations on a wheel’s surface. The drop hammer, typically used for evaluation of draft gears, is located at ASF-Keystone in Camp Hill, PA, and can impart dynamic loads up to a maximum of 2,000 kips, which is well in excess of typical wheel impact loads recorded by wayside impact detection systems. Impact loads for drop hammer wheel testing were generally confined to a maximum of approximately 200 kips. Finite element analysis (FEA) modeling using only mechanical tread loading was conducted to determine the high stress locations for the wheel design and to correlate strain gauge results for static loading on the wheel. The instrumented drop hammer used for wheel impact testing is described, and wheel strain gauge issues are discussed. Vertical split rim wheel failures are described and are briefly reviewed. The implications of impact loading for vertical split rim wheel failures are discussed and recommendations for future work are offered.
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Sura, Venkata S., e Sankaran Mahadevan. "Vertical Split Rim Failure Analysis in Railroad Wheels". In 2010 Joint Rail Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/jrc2010-36024.
Testo completoAbstract (sommario):
Vertical split rim cracking, rapid unstable propagation of a sub-surface crack parallel to the front rim face, is one of the dominant railroad wheel failure types observed in North America. Wheel impact load is believed to be a trigger for this unstable crack growth. This rapid crack growth rate depends on several factors, such as wheel geometry (wheel diameter and rim thickness), load magnitude, load location, residual stresses in the rim, worn tread profile, and material defects in the rim (size, shape, location, and orientation). This paper investigates the effect of these parameters on vertical split rim cracking, using finite element analysis and fracture mechanics. Vertical split rim cracking is modeled using a three-dimensional, multiresolution, elastic-plastic finite element analysis. Material defects are modeled as mathematically sharp cracks. Wheel impacts are simulated by applying a high axle load on the tread surface. The residual stress and wheel wear effects are also included in modeling vertical split rim cracking.
7
Jimin, Zhang, Wan Jingyuan, Li Wen, Zhong Xujie, Zhou Hechao, Qi Yuan e Hou Chuanlun. "Research on Simulation of Resilient Wheel Dynamometer". In 2020 Joint Rail Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/jrc2020-8069.
Testo completoAbstract (sommario):
Abstract Among many testing items of infrastructure, wheel-rail force is an important factor that causes track failure, damage, train derailment and vehicle parts damage. It is also used to evaluate the ride stability, safety and as the main basis for speed limit and speed increase. Among many methods of wheel-rail force detection, the method of wheel-rail force measurement is the most accurate and direct method of wheel-rail force measurement. The method of measuring wheel-rail interaction force using wheelset of railway locomotive and rolling stock as force sensor has the highest accuracy among all wheel-rail force measurement methods. Force-measuring wheelset is the core sensor in the dynamic test research of railway vehicles, and its performance directly affects the evaluation results of the tested objects. Before the actual line test, it is necessary to calibrate the dynamometer wheelset on the test bench. The calibration of dynamometer wheelset is an important link in the research and application of dynamometer wheelset. With the rapid development of rail transit in various countries and the great improvement of locomotive and rolling stock manufacturing technology, higher and higher requirements has been put forward for the performance of force-measuring wheelsets, which are mainly embodied in obtaining ideal sensitivity and linearity, minimizing cross-interference and all kinds of possible external interference, and reducing the influence of the change of the position of the action point on the measurement results. For the rigid wheelset, the calibration of the force-measuring wheelset is basically perfect from the actual production to the algorithm. The relevant countries also determine the calibration in the standard form. At present, more and more urban rail low floor vehicles are using independent resilient wheels. The mechanical structure of the bogie with resilient wheels is complex. At the same time, because of the small diameter of the resilient wheels and the rubber layer between the wheel hoop and the wheel center, it is difficult to find the strain/stress sensitive area accurately, as well as the unique installation process, the calibration of resilient wheels is rather difficult. This paper takes the low floor resilient wheels as the research object, and studies how to make the calibration method of high precision and suitable for the independent rotating wheels of resilient wheels and the processing and analysis of calibration data. The main research contents are as follows: the development of force-measuring wheelset which is based on the finite element simulation of a resilient wheel, stress distribution analysis, and the fabrication scheme of force-measuring wheelset which meets the requirement of test accuracy is proposed by using virtual bridge formation.
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Jin, Xuesong, Jun Guo, Xinbiao Xiao e Zefeng Wen. "An Investigation Into Effect of Train Curving on Wear and Contact Stresses of Wheel and Rail". In ASME 2008 9th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2008. http://dx.doi.org/10.1115/esda2008-59373.
Testo completoAbstract (sommario):
Some important papers concerning the studies on rail wear and wheel/rail contact stresses are reviewed. The present paper utilizes a numerical method to analyze the effect of railway vehicle curving on the wear and contact stresses of wheel/rail. The numerical method considers a combination of Kalker’s non-Hertzian rolling contact theory, a material wear model and a vertical and lateral coupling dynamics model of a half vehicle and a curved track. The present analysis investigates the influence of the curving speed, the curved track super-elevation and the rail cant on the wear and the contact stresses. Through the detailed numerical analysis, it is found that the maximum contact stress depends greatly not only on the curving speed but also on the profiles of the wheel/rail. The curving speed increasing leads to increase the normal load of the wheel rolling over the high curved rail, but, decrease the normal contact stress level under the condition of the optimum match of wheel/rail profiles. The track super elevation increasing efficiently lowers the contact stresses and the wear at a constant curving speed. The rail cant has a great influence on the low rail wear of the curved track. Increasing the rail cant leads to the great growth of the low curved rail wear, the reduction in the high rail wear. The results are very useful in the maintenance of the track.
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Ba˘rbiˆnt¸a˘, Constantin I., Sulleyman Yaldiz, Alina Dragomir e Spiridon S. Cret¸u. "An Elastic-Plastic Solver of the Wheel-Rail Contact". In ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-24793.
Testo completoAbstract (sommario):
Wheel and rail in service undergo continual wear and plastic deformation at the surface, so that in time all wheel profiles will be different. The optimization by grinding a worn rail profile to minimize contact stresses requires the development of a software to reconstruct a rail profile using circular arcs. A working algorithm, able to be incorporated into a computer code, has been developed to solve the stress state in the general case of non-Hertzian contacts. To limit the pressure, an elastic-perfect plastic material has been incorporated into the computer code. The pressure distribution and the corresponding stresses states have been investigated for pure normal loadings, as well as for the combined, normal and tangential loadings. The elastic-plastic analysis model allows fast investigations regarding the influence of different parameters such as load level, contact geometry including the geometry of the worn profiles.
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Stewart, Monique F., Som P. Singh, David R. Andersen, Rou Wen e Graydon F. Booth. "Wheel Temperature Reduction During Freight Car Braking". In 2016 Joint Rail Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/jrc2016-5819.
Testo completoAbstract (sommario):
Since the adoption of 286,000 lb gross rail load (286K GRL) car service, an increase in wheel thermal damage and shelling has been observed. This is attributed to the increased braking horsepower in 286K GRL service as compared to the 263K GRL service environment. This study investigated possible designs and methods of braking that could lead to reduced heat input to the tread of freight car wheels in order to mitigate this damage and reduce its occurrence to a level closer to that seen with 263K GRL car service. Fifteen potential concepts to lower the thermal input to wheels and/or accelerate heat removal from the tread were identified and evaluated using the following engineering categories: simplicity of design, maintenance requirements, weight considerations, material and manufacturing costs, controllability of braking effort, and market acceptability. Five final concepts — axle-mounted disc, cheek disc, wheel rim, axle-mounted drum, and high convection coating — were developed through preliminary design and thermal analysis to confirm their effectiveness in meeting the objectives. Four concepts for alternative braking methods — axle-mounted disc brakes, cheek disc brakes, wheel rim clasp brakes, and axle-mounted drum brakes — were analyzed in considerable detail. Of the four concepts presented, the first three appear to be feasible and would be potential candidates for further detailed investigations/evaluation. It is shown that as the demand on railway wheels to withstand increased mechanical and thermal loads grows, there are viable braking enhancements that can help manage the stress state in freight car wheels.
Rapporti di organizzazioni sul tema "STRESS ANALYSIS OF RAIL WHEEL"
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Heymsfield, Ernie, e Jeb Tingle. State of the practice in pavement structural design/analysis codes relevant to airfield pavement design. Engineer Research and Development Center (U.S.), maggio 2021. http://dx.doi.org/10.21079/11681/40542.
Testo completoAbstract (sommario):
An airfield pavement structure is designed to support aircraft live loads for a specified pavement design life. Computer codes are available to assist the engineer in designing an airfield pavement structure. Pavement structural design is generally a function of five criteria: the pavement structural configuration, materials, the applied loading, ambient conditions, and how pavement failure is defined. The two typical types of pavement structures, rigid and flexible, provide load support in fundamentally different ways and develop different stress distributions at the pavement – base interface. Airfield pavement structural design is unique due to the large concentrated dynamic loads that a pavement structure endures to support aircraft movements. Aircraft live loads that accompany aircraft movements are characterized in terms of the load magnitude, load area (tire-pavement contact surface), aircraft speed, movement frequency, landing gear configuration, and wheel coverage. The typical methods used for pavement structural design can be categorized into three approaches: empirical methods, analytical (closed-form) solutions, and numerical (finite element analysis) approaches. This article examines computational approaches used for airfield pavement structural design to summarize the state-of-the-practice and to identify opportunities for future advancements. United States and non-U.S. airfield pavement structural codes are reviewed in this article considering their computational methodology and intrinsic qualities.