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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.
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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.
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Telliskivi, Tanel. "Wheel-rail Interaction Analysis." Doctoral thesis, KTH, Machine Design, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3532.
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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
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Zhan, Yun, and 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.
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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.
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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.
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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/.
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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.
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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.
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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.
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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.
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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.
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Brabie, Dan. "On Derailment-Worthiness in Rail Vehicle Design : Analysis of vehicle features influencing derailment processes and consequences." Doctoral thesis, Stockholm : Farkost och flyg, Kungliga Tekniskan högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4548.
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Fišer, Petr. "Analytický řešič pro pevnostní výpočet náprav dvojkolí." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230008.
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This master thesis deals with wheel set axles of rail vehicles, their design and methods of implementation stress analysis. In this work, I created a powered locomotive wheel set: axle and wheel. For the purpose of the design department of the Bonatrans Group a.s. company I developed an analytical solver, which allows creating stress analysis, which will be used for verifying finished design and in addition it allows printing of stress analysis as report for the railway´s offices. Next step was a stress analysis of this design of axle in this analytical solver.
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Nishiyama, Kenta. "Analysis of Soil-Tire Interaction Using a Two-Dimensional Finite Element-Discrete Element Method." Kyoto University, 2019. http://hdl.handle.net/2433/245298.
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Klepetko, David. "Optimalizace kovaných vysokotlakých elementů zásobníku paliva systému common rail." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228379.
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The subject of this thesis is the optimization of forged high pressure elements of fuel accumu-lator of Common Rail System. The aim of this work is to assess the current state and design the individual high pressure elements in the CAD system. There is implemented strain and stress analysis in the FEM system Abaqus/CAE and in fatigue postprocessor FEMFAT for all designs. On the basis of this analysis are proposed optimized design solutions.
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Santos, Francisco de Carvalho. "Modelo numerico elastoplastico de contato com rolamento aplicado a analise de fadiga de rodas ferroviarias." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263980.
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Orientador: Auteliano Antunes dos Santos JuniorDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Este trabalho propõe um modelo numérico de contato roda-trilho, baseado no método dos elementos finitos, para estimar a vida em fadiga até o surgimento da trinca, e quanto à falha por escamação, de uma roda ferroviária classe C de um vagão de carga de uma ferrovia nacional, de Serra dos Carajás. O modelo tem como principal contribuição à abordagem elastoplástica juntamente com a inclusão das tensões residuais provenientes do tratamento térmico do processo de fabricação da roda. O modelo de elementos finitos utilizou técnicas de submodelagem, tanto na determinação no campo de tensões residuais de fabricação, quanto no de contato roda-trilho. Para efeito de comparação, determinaram-se as tensões e deformações também com um modelo semi-analítico elástico, baseado na teoria de Hertz, além de um modelo numérico elastoplástico sem tensões residuais de fabricação. A vida foi determinada através de dois critérios de fadiga, que incorporam a influencia das tensões hidrostáticas e planos críticos. O critério de alto ciclo de Dang Van foi modificado para adaptar-se ao problema de dois corpos em contato. O outro critério utilizado foi o de Fatemi¿Socie, baseado em deformações cisalhantes. O número de ciclos encontrado para o início da trinca foi então corrigido de acordo com uma distribuição normal estatística da posição lateral do ponto de contato. O trabalho mostrou que as tensões residuais, benéficas para a propagação de trincas, reduzem a vida até o surgimento destas
Abstract: This work proposes a wheel-rail contact model based on finite element method to estimate the fatigue life to shelling, until the beginning of the crack of a railroad wheel class C of a heavyhull Brazilian railroad from Serra dos Carajás. The main contribution of this work is the elastoplastic approach with the inclusion of the residual stress generated by the heat treatment of the wheel manufacture process. Submodeling techniques were used to determinate the residual stresses from manufacture process and the contact stresses. Aiming the comparison, the wheelrail contact stresses was calculated using an analytic model, based on Hertz theory, and a numeric model (FEM) without residual stress from the manufactured process. The fatigue life was calculated using two criterions based on critical planes and hydrostatic stresses. The high cycle fatigue criterion from Dang Van was adapted to be used in contact problems. The other one was the Fatemi¿Socie criterion, based on shear strains. The number of cycles until the arising of the fatigue crack was correct using a statistical normal distribution of the lateral position of the contact point. This work shows that the residual stress generated by the manufacture process, which prevents the crack propagation, reduces the fatigue life until the arising of the crack
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Doutor em Engenharia Mecânica
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Kapoun, Lukáš. "Konstrukce disku kola osobního automobilu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231270.
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The present master thesis deals with the design of wheel disk for passenger car. The review part of this thesis summaries the history and development of the wheel; this is followed by a description of individual construction types of wheel disk for passenger car presently used. The construction part of this thesis provides a design of disk of given parameters based on the analysis of forces acting on the car wheel. For the purposes of design, the stress and fatigue analyses are performed.
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Štursa, Martin. "Výložník kombinovaného skládkového stroje." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230556.
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This master’s thesis deals with the construction of parts of a bucket-wheel stacker/reclaimer designed to operate lignite stockyard at coal power plant. First the basic parameters of machine and loads applied in service are defined. The work also includes the design of steel structure of bucket-wheel boom, bucket-wheel, buckets, bucket-wheel drive, shaft, bearings and other parts of bucket-wheel boom. These parts are verified by analytical or finite element analysis.
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Merino, Pierrick. "Reproduction expérimentale du contact roue-rail à échelle réduite : Voies de formation des sources de défauts." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI101.
Full textAbstract:
Face au développement du transport ferroviaire, la sécurité demeure la principale préoccupation des exploitants de réseaux ferrés. En particulier, la compréhension des phénomènes sources des défauts de fatigue de roulement (RCF) mettant en jeu l’intégrité du rail, est nécessaire pour limiter les risques d’accidents. La phase blanche, associée à la formation du défaut de squat, est difficile à reproduire mécaniquement en laboratoire. L’utilisation de bancs d’essai permet de reproduire plusieurs aspects du contact roue-rail selon des critères choisis, mais nécessite de faire des compromis. Le banc Triboring développé au LaMCoS avec la RATP, comble un manque en proposant notamment une géométrie galet sur rail circulaire pour reproduire au mieux les conditions tribologiques du contact roue-rail. Le développement d’un banc d’essai nécessite d’évaluer sa « signature », c’est-à-dire d’identifier et de discerner les phénomènes mesurés correspondant à la réponse intrinsèque du banc en fonctionnement, de ceux correspondant à la réponse de l’interaction roue-rail considérée. Une analyse notamment dynamique et cinématique a permis de caractériser le banc et d’optimiser sa réponse en faisant évoluer la géométrie des éprouvettes. La réponse tribologique du banc a été optimisée par l’introduction d’une couche qualifiée de « fusible tribologique », lors de la préparation des éprouvettes. Cette couche surfacique permet de retarder l’accommodation des vitesses par usure au profit du cisaillement des premiers corps et des Transformations Tribologiques de Surface (TTS), telles que la phase blanche. Deux couches fusibles, écrouies et corrodées ont été éprouvées, et permettent une nette réduction de l’usure. Les analyses tribologiques et métallurgiques des bandes de roulement en surface et des coupes ont permis d’appréhender l’effet des différentes sollicitations mécaniques sur l’évolution de la microstructure du rail en proche surface. La transformation de cette dernière amène le matériau vers la formation d’îlots de phase blanche d’origine mécanique à la surfaceThe safety issue is still the main concern of railway network due to the development of railway transportation and the increase of the amount of passengers. The understanding of the origin of the rolling contact fatigue (RCF) defect, is one key to safety requirements. The White Etching Layer associated to the initiation of the squat defect is hardly recreated. The use of laboratory test bench enable the replication of the wheel-rail contact. Nevertheless, only a fraction of the characteristic parameters is taken into account and compromises are necessary. The test bench “Triboring” built at LaMCoS, fulfills a gap in the existing apparatus. The “roller on circular rail” design was chosen to fit the tribological behavior of wheel-rail contact, and replicate RCF defects. The production of a test bench required to relate and differentiate the measured data to the phenomena corresponding to the operating from the phenomena corresponding to wheel-rail contact. The bench was characterized with dynamic and cinematic analysis. The design of the sample was improved. The tribological behavior of the bench was optimized with the preparation of the initial surface of the samples and the production of a tribological “fuse”. This layer delays the speed accommodation by wear and benefit the shear of the first bodies and the formation a Tribological Transformation of Surface (TTS), as the White Etching Layer. The two different fuse layer created (Run-in and oxidized), induced a significant wear reduction. The tribological and metallurgical analysis of the surfaces and cuts of the sample, enabled to the explanation of the evolution of the microstructure of the rail close to the surface, submitted to various mechanical solicitations. The transformation of this microstructure led to the formation of white etching layer mechanically formed
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Elsayed, Abdel Hameed Amer Shaltout Ramy. "MULTIBODY APPROACH FOR RAILWAY DYNAMIC ANALYSIS." Doctoral thesis, Universitat Politècnica de València, 2013. http://hdl.handle.net/10251/27622.
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En este trabajo se ha llevado a cabo el desarrollo de una herramienta computacional para la simulación dinámica de vehículos ferroviarios. El modelo está basado en técnicas multicuerpo debidas a Shabana. Con respecto a otras metodologías existentes, la propuesta hace uso de un conjunto de sistemas de referencia que permite el empleo de coordenadas independientes sin la posibilidad de configuraciones singulares debidas a grandes giros. El conjunto de sistemas de referencia sirve de base para formular de manera precisa el problema de contacto rueda-carril. El programa está diseñado para considerar de forma flexible distintas configuraciones de vehículo así como diversas geometrías de trazado. La estructura del programa está abierta a cambios orientados a la mejora del modelo de contacto rueda-carril o a la implementación de la dinámica estructural de la vía. Se ha implementado un modelo eficiente que permite detectar con precisión las coordenadas de los puntos en contacto localizados en la interfase entre la rueda y el carril. La herramienta de simulación desarrollada en esta tesis se ha aplicado para diferentes casos-estudio con el objetivo de validar la idoneidad de la metodología propuesta en el análisis del sistema ferroviario. Se ha realizado una comparación entre los resultados obtenidos por la herramienta de simulación presentada y los resultados ofrecidos por varios programas comerciales de simulación dinámica en el análisis del vehículo de Manchester Benchmark. Además, la herramienta se ha empleado para desarrollar un análisis dinámico del vehículo de la locomotora TGV y los resultados obtenidos se han comparado con los ofrecidos por el programa comercial SIMPACK para el mismos modelo de vehículo, bajo las mismas condiciones de operación. Finalmente, sobre la base de la calidad de los resultados, se puede concluir que la herramienta de simulación es fiable y eficiente para emplearse en el análisis dinámico de los diferentes sistemas ferroviarios.Elsayed Abdel Hameed Amer Shaltout, R. (2013). MULTIBODY APPROACH FOR RAILWAY DYNAMIC ANALYSIS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/27622
TESIS
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Brabenec, Ladislav. "Topologicko-geometrický návrh a deformačně-napjatostní analýza tvaru disku železničního kola pro různé provozní podmínky na základě analýz LELM." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229933.
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The thesis deals with the behaviour of a cracked rail wheel. The aim was to perform the strain analysis of intact wheel as well as the fracture analysis of the primary direct cracked wheel. Solution includes an analysis of operating conditions, assessment of the substantiality of articular components of load, stiffness of the wheel, a comprehensive analysis of fracture of the selected railway wheel profile and optimization of the wheel shape depending on the matching fracture properties.
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Maddela, Naveen. "Finite Element Analysis of Railway Track Wooden Sleeper." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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Railway sleepers have important roles within the complex railroad. Dynamic interaction among Rail, sleeper and ballast supports are vital for the construction of dynamic model track capable of predicting its responses to impact loads due to wheel flats, wheel burns, irregularities of the rail. Railway track deteriorates over time due to the dynamic loading of passing wheeled vehicle. to ensure the secure passing of trains, the track must well design and managed.The objective of this thesis is to determine the stress in wooden rail sleeper by the considering Ballast, Sub ballast, and soil with the help of well-known FEM Tool Ansys Workbench. Material models for wooden sleeper and subgrade are anisotropic elasticity and elasto plastic (Drucker Prager), respectively. To validate FEM results with analytical Zimmermann method, perform the 2D linear static analysis and 3D nonlinear static analysis. The numerical analysis results in Ansys Work bench are presented and discussed the model validation with analytical results. Even though simulation converged it does not mean this model could give results similar to reality. But in my opinion these results are not sufficient to study the behavior of wooden sleeper because limitations in soil mechanics (Soil Models in Ansys Workbench).
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Rec, Matouš. "Návrh testovacího stavu pro stanovení opotřebení u kontaktu železničního kola a kolejnice." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-445166.
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This diploma thesis focuses on the issue of a wear of a railway wheel and a rail. The wear of the components depends on a number of parameters including the contact stress, the contact pressure and the contact surface dimensions. Among the factors determining these parameters belongs primarily the wheel driving gauge, the rail profile and the load of the contact area. Furthermore, the material from which the wheels and rail are made, the roughness and hardness of the functional surfaces and the residual stress in the material have a significant impact on the wear. All the parameters mentioned above are designed for the production of the railway wheels and rails and therefore they meet the standards for the production of these components. However, the existence of the changeable parameters has also a significant impact on the wear. These parameters include the presence of contaminants, or lubricants in contact, the changing driving gauge due to the wear, the slip ratio or the friction coefficient. With the wear being an inevitable process during the application it cannot be eliminated but only controlled. Applying the lubricant into the contact when passing through the arc in order to achieve an ideal coefficient or the maintenance grinding for restoring the driving gauge can serve the purpose. If properly optimized, the importance of the wear research lies in the financial savings. Being the crucial factor for optimization of the intervals between the maintenance grinding, the research is also beneficial. A high-quality wear prediction can be seen as the key field in order to increase the safety of the railway vehicles operation as well. Therefore, the wear research is made using several methods, such as the computational models, the multi-body dynamics software and the technical experiments. This thesis introduces a conceptual design of the test, enabling the wear research via experimental approach. The final device is capable of a simulation of both volume and fatigue wear during the states the railway wheel and railway undergo including riding on the straight track, passing through an arc or a wheel slip during braking.
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Lysák, Jan. "Změna konstrukce profilu dveřního křídla pro kolejové vozidlo." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231683.
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This master thesis deals with creation computional model of specific door leaf which was researched and now is provided by company named IFE-CR, a.s. Finite element method analysis is performed within the standards for load conditions during the operation. Stress-strain response should be the main factor to comparing results with experiment on real door. Based on acquired knowledge from the original model we can evaluate credibility of mechanical behavior of newly designed model which has lower profil tapered from the original 42 mm to 25,4 mm. From the results of FEM analysis of the modified profile is evaluated applicability to the real operational state. At the end is quantified material and financial savings achieved by reducing the height of profile.
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Felcman, Miroslav. "Pomocný podvozek pro nosič výměnných nástaveb s návěsovým čepem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231764.
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Main purpose of the thesis is to carry out a design and a check up of an auxiliary chassis for swap bodies with king pin. The thesis contains pictures of auxiliary chassis made by different producers, followed by my own design. The design contains my own concept of the chassis with purchased parts included. The design of a frame of the auxiliary chassis has been taken in for stress analysis during a number of test loads. Last part of the thesis contains results of stress analysis. Drawings of selected parts are also included. The thesis has been made in cooperation with ZDT Nové Veseli s.r.o.
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Mohyla, Daniel. "Konstrukční návrh nábojů kol vozidla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378495.
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This diploma thesis deals with design of a wheel hub assembly for a Formula Student vehicle. First part of this thesis is dedicated as an introduction to the Formula Student competition and serves as a summary of design solutions for wheel hubs with a focus on open wheel vehicles. Second part deals with description of a problem and summarizes necessary knowledge and information to solve given problem. Third part is devoted to CAD modelling in software PTC Creo parametric. This model is then analysed using finite element method. Last part of this thesis is a discussion about achieved results and discussion about further potential improvements is carried out.
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Blach, Jiří. "Konstrukční návrh pryžové spojky pro aplikaci v kolejové dopravě." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417544.
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The diploma thesis deals with the design and stress-strain analysis of a flexible coupling composed of individual rubber-textile segments. This concept allows the manufacturer to simplify and unify the production thanks to the ability to use a single segment design for multiple coupling configurations and thus leads to a reduction in costs on the part of the manufacturer. From the consumer side this allows only mechanically or chemically damaged segments to be replaced instead of the entire coupling and saves costs for the potential user. The coupling assembly is primarily designed according to the parameters of intercity electric units and locomotives, however, the individual flexible segments are not limited by this use. When designing a coupling assembly, it is necessary to place requirements primarily on the high safety of all components. The operating mode, in which the relative displacement of the input and output shafts can occur, indicates a relatively wide range of transmitted loads which, if any assembly part is improperly designed, can cause problems leading to temporary putting the entire machine/vehicle out of order. The most critical areas of the assembly include the flexible segments, the bolt connections, the strength of the hubs and the spline joint for torque transfer. Last but not least, the requirements for the non-complex production of components must be taken into account, together with the assembly and maintenance without collision of the components and the necessary tools. In order to verify the above-mentioned requirements, stress-strain analyses are performed simulating the variation of operating load conditions. Due to the reduction of hardware requirements and computational time, together with the absence of experimentally measured data of rubber and PES codes, the flexible segments were modelled at a lower level with a reduced material model favouring the tensile properties of PES cords. However, this reduction provides a more conservative approach, as this use causes higher stresses on the steel components of the assembly. Subsequently, a stress analysis of the splined joint is performed. Due to the absence of specific shaft geometry models of commercial motors and gearboxes, a parallel splines were chosen for this purpose and designed according to the specified maximum torque. The last part of the thesis is focused on verifying the tensile properties of an individual flexible segment.
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Hrabovský, Jozef. "Optimalizační analýza brzdového kotouče." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-227872.
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Subject of this diploma thesis is break wheel optimalization analysis. Break wheels are used in mountain bike downhill races in extreme conditions. It is the first product of this type of an emergent company that was made by the use of intuitive approach. The reason for optimalization is improper behavior of existing solution that occurred during testing. This optimalization consists of finding and analyzing existing characteristics, deciding which factors influence this improper behavior, suggesting new solution and verification of this solution. Break wheel characteristics were detected in an experiment. For realization and evaluation of this experiment, a method named Design of experiments, was selected. This method is used for elaboration of results coming from the Regression analysis. It is possible to effectively achieve the result data by using this procedure. The experiment was oriented to gain data of temperature behavior of break wheel during real load. Mathematical model was adapted on the basis of this data and finally, the calculation was made by the use of Final element method by ANSYS WORKBENCH. Calculations were also coordinated through Design of calculation, and were oriented on temperature deformation and stress. Solution achieved by the Final element method, was evaluated by the Regression analysis and served as a proposition for a new break wheel construction.
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Суков, Максим Геннадійович. "Обґрунтування параметрів великогабаритних хвильових зубчастих передач приводів потужних машин." Diss., Національний університет "Львівська політехніка", 2021. https://ena.lpnu.ua/handle/ntb/56684.
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Силовий аналіз деформованого зубчастого зачеплення заснований на фізичних та математичних моделях, які охоплюють тривимірну силову взаємодію гнучкого елемента у сполученнях вищих кінематичних пар. Теоретичні та експериментальні дослідження комплексних моделей забезпечили підвищення точності результатів тривимірного кількісного та якісного розподілення сил у зубчастому зачепленні, а також дозволили визначити граничні умови прояву інтерференції та проскакування зубів.
Дослідження кінематичних процесів у зубчастому зачепленні хвильової передачі, дозволили визначити швидкості точок гнучкого колеса у радіальному w та коловому v напрямках, та швидкість ковзання зубів
VS , оцінити поле зачеплення за критеріями мінімізації швидкості ковзання, зношування та заклинювання зубів, енергетичних втрат. Розроблені математичні моделі напружено-деформованого стану гнучкого колеса у вигляді циліндричної оболонки защемленої по торцям, зубчастого та шліцьового вінців з’єднаних циліндричною оболонкою, для розрахунку методом кінцевих елементів. Це дозволило встановити розподілення напружень, а також лінійні та кутові деформації гнучкого колеса. Встановлено вплив конструктивних факторів на інтерференцію та енергетичні втрати у зубчастому зачепленні хвильової передачі. Величина енергетичних втрат здебільшого зумовлена великою протяжністю поля зачеплення. Порівняльний аналіз отриманих результатів підтвердив адекватність виконаних теоретичних та експериментальних досліджень, що забезпечило суттєве зниження енергетичних втрат та підвищення навантажувальної здатності великогабаритних хвильових редукторів. The dissertation is devoted to the development of scientific methods and means of increasing the load capacity of large wave gears, which is especially relevant for heavy engineering. The force analysis of deformed gearing is based on physical and mathematical models that cover the three-dimensional force interaction of a flexible element in combinations of higher kinematic pairs. Theoretical and experimental studies of complex models have improved the accuracy of the results of three-dimensional quantitative and qualitative distribution of forces in the gearing, as well as allowed to determine the boundary conditions for the manifestation of interference and skipping teeth. Studies of kinematic processes in the gearing of the wave transmission, allowed to determine the velocities of the points of the flexible wheel in the radial and circular directions, and the speed of sliding teeth, to evaluate the gearing field by minimizing the speed of sliding, wear and jamming of teeth, energy losses. Mathematical models of the stress-strain state of a flexible wheel in the form of a cylindrical shell clamped at the ends, toothed and splined crowns connected by a cylindrical shell have been developed for calculation by the finite element method. This allowed to establish the stress distribution, as well as linear and angular deformations of the flexible wheel. The influence of design factors on interference and energy losses in gear transmission of wave transmission is established. The magnitude of energy losses is mainly due to the large length of the engagement field. Comparative analysis of the obtained results confirmed the adequacy of the performed theoretical and experimental studies, which provided a significant reduction in energy losses
and increased load capacity of large wave reducers. The distribution of the normal effect of the boundary effect on the stress state of the shell of the HA is associated with bending stresses and their size decreases with decreasing shell thickness. The maximum stresses associated with the edge effect occur near the end of the shell, connected to the ring gear, where a smooth transition should be provided, which takes into account the negative stress concentration factor. When the thickness of the HA is halved (h = 6.75 mm), the tangential tensile stresses increase to t max = 40 MPa, and the bending stresses as a result of the edge effect decrease to values of the same order. The maximum compressive and tensile stresses are equal to each other in
order. The maximum compressive and tensile stresses are equal in absolute value = - 26 MPa, = +26 MPa.
It is established that the reduction of the maximum normal bending stresses to the level of the maximum tangential torsional stresses tmax improves the stress-strain state of the HA, increases the load capacity and service life of highly loaded VGHR. The performed researches allow to establish stresses and deformations of GK necessary for optimization of parameters of VGHZP. The distribution of the normal load on the HA from the action of the GC, the dependence of the radial force R acting on the disks, on the value of the torque M2 is obtained experimentally. On the basis of experimental researches it is established that efficiency of VGHR accepts the maximum value at nominal loading, thus frequency of rotation of an input shaft is regulated within. At maximum load, the efficiency decreases by 3% and at the speed of the input shaft is With increasing
speed n1 within (50… 750) rpm, the efficiency decreases by 2%. The goal set in the dissertation is achieved, the formulated tasks are successfully solved. The obtained scientific results are used in heavy engineering as guiding technical materials for design and design work of wave reducers. According to the results of the performed researches, 16 large-sized wave reducers with a total weight of 112492 kg with reduced dimensions, weight by 77218 kg (40.7%) and labor intensity of manufacturing by 4250 standard hours (30.8%) lower than the existing ones were developed and introduced into production. The economic effect from the introduction of the developed wave reducers at PJSC NKMZ amounted to UAH 2,205,934.
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Hušek, Martin. "Londýnské oko." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227180.
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Performance of static analysis of the London Eye structure is the subject of this diploma thesis. First chapters of the thesis analyses overview of realized structures of the Ferris wheel. The main part of the thesis analyses the London Eye structure itself. Specifically are described response analyses, sensitivity analyses, analyses of ultimate limit state and serviceability, stress analyses, analyses of fatigue stress and lifetime analyses. The thesis describes among static analysis also a design of dynamic vibration absorbers. The results of each analysis are evaluated in the final chapters.
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Navrátil, Václav. "Snižování hluku kolejových vozidel v traťových obloucích." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400957.
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SINGH, DEVENDRA. "COMPUTATIONAL STRESS ANALYSIS OF RAIL-WHEEL MODEL OF INDIAN RAILWAYS." Thesis, 2016. http://dspace.dtu.ac.in:8080/jspui/handle/repository/14637.
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ABSTRACT
Wheel-rail contact analysis is one of the most standout problems in the modeling and analysis of
railway vehicles. The wheel-rail interaction is an exceptional part of rail-vehicle progress as it
accounts for the capacity of freight wagon and is being considered the most critical parameter for
the freight traffic wagons on the railway tracks. In this thesis, the static response of the wheel on
a rail is analyzed by modelling and analyzing the geometries of standard section of Rail and
wheel through the softwares Creo parametric 2.0 and Ansys 15.0 for calculating the stresses
between the Rail-wheel contact region. An analytical approach for calculating the tangent
modulus has been drafted during the selection of material and its properties using the Ramberg
Osgood Equation. The Hertzian contact theory gives the expression for the maximum contact
shear stress value at the point of contact between the rail and the wheel. To validate the value of
contact shear stresses founded in this thesis, responses of the assembled model using Ansys 15.0
are compared with the Hertzian approach as well as with the Hertzian stress calculator. Then it
has been found that all the three maximum contact shear stresses achieved by different methods
are less than the standard limiting values of maximum contact shear stresses in accordance to the
Indian Railway Standard. Finally the effects of the results have been studied for the essence of
analysis.
Maximum contact shear stress between Rail-wheel is found to be 25.5 kg/mm2, 24.63 kg/mm2,
23.55 kg/mm2 by Ansys 15.0, Hertzian theory and Hertzian stress calculator respectively for 90
UTS rail of UIC 60 kg section and all are less than the limiting value of contact stress which is
27.0 kg/mm2 for 90 UTS rails and it was the prime objective of thesis.
The thesis is divided into six chapters. The first chapter describes the introductory part of Indian
Railways and importance of Freight traffic, followed by the scope and domain of the freight
traffic. The next chapter gives an insight regarding the Railway track, rails and wheels, apart
from this the chapter also focuses on theory of contact stresses as well as bending stresses.
Chapter three, describes the processing of modelling of Rail UIC 60 kg (90 UTS) and wheel of
BOXN standard, followed by the fourth chapter which accounts for the computational static
analysis of the assembled model of rail and wheel. Chapter five, represents the result validation
of contact shear stress and compares it with the limiting values in accordance to Indian Railway
Standard. Chapter six delineates the conclusion.
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Lin, Ray-Shang, and 林瑞盛. "Three Dimensional Stress Analysis of Aluminum Wheel." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/00384510176632741995.
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碩士國立成功大學
機械工程研究所
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Computer aided analysis becomes a powerful tool in developing new products such that the production cost can be saved and the design period is reduced. This paper describes the application of the finite element method to the three dimensional stress ana- lysis of aluminum wheels by using computer aided software ANSYS. The magnitudes and patterns of stress distribution are consistent with the results obtained from experiment. Moreover, the effect of reinforce stringer on the reduction of stress concentration has proved to be significant. Consequently, the refined model of the wheel structure is useful for weight-saving design.
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Zhu, Jian Jun. "Development of an adaptive contact model for analysis of wheel-rail impact load due to wheel flats." Thesis, 2006. http://spectrum.library.concordia.ca/9251/1/zhu_jian_jun_2006.pdf.
Full textAbstract:
The discontinuities in surface profiles of railway wheels, commonly known as wheel flats, are known to impose excessive impact loads at the wheel-rail interface. Such impact loads can cause premature fatigue and failure of the vehicle-track system components, and impede the operational safety. The safe and cost-effective operations of railways thus necessitate continuous monitoring and control of impact loads induced by wheel defects. In this dissertation research, an adaptive wheel-rail contact model is developed to predict contact geometry and impact force as a function of flat geometry, speed and normal load. The model employs radial contact springs and could simulate for either single or multiple wheel flats. Unlike the commonly used Hertizan nonlinear models, adaptive model predicts the contact geometry involving either total or partial contact in the presence of a wheel defect in the contact patch. The proposed contact model is integrated to a roll plane model of vehicle and a three-dimensional flexible track model to derive a coupled vehicle-track system model. The vehicle is modeled as a six-DOF lumped mass system including carbody, bolster, sideframe, wheelset, and primary and secondary suspensions. The track system model considers two parallel Timoshenko beams periodically supported by lumped masses representing sleepers. The rail-pad and ballast are also included through linear visco-elastic elements. Central finite difference technique is employed to solve for the coupled partial and ordinary differential equations of motion for the continuous and discrete system models, respectively. The dynamic response of the wheel-track system is initially investigated under a constant moving load to examine validity of the model and the numerical method. The impact force response of the adaptive contact model in the presence of a single wheel flat revealed reasonably good agreements with available measured data. This agreement was better than that provided by the well-known Hertizan nonlinear point contact model. The results further revealed that discrete sleeper supports act as sources of excitations. The results attained from the parametric study revealed that the normal load, speed and flat size are the primary factors that affect magnitudes of impact forces, while the suspension parameters show only minor effects. Some of the parameters of the track system also revealed important effects on magnitudes of impact force. The coupled vehicle-track system is further analyzed to derive the impact force properties for different wheel flats, operating speeds and loads. The analyses were also performed for single as well as two flats within the same or two opposite wheels of a wheelset. The results suggested that magnitudes of impact forces attributed to the second flat were strongly affected by responses to the preceding flat. The resulting peak impact force may be either higher or lower than that caused by a single flat, depending upon flats geometry, relative coordinates of the flats and operating speed. The results further suggest that the length of a flat, which is regarded as the removal criteria by AAR and Transport Canada, is not sufficient for cases involving either single or multiple flats
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Chia-LingHsieh and 謝佳陵. "Numerical Stress Analysis of Bonded Insulated Rail Joints." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/vj349f.
Full textAbstract:
碩士國立成功大學
土木工程學系
104
In the study, the finite element package of ABAQUS is utilized to numerically analyze the stress distributions of bonded insulated rail joints with different geometries and material properties. At first, a numerical model composed of rails, joint bars, epoxy, bolts, insulated sleeves for bolts, insulated sheet between rails, and sleepers, was generated by using the finite element software. Next, a vertical concentrated load was imposed on the bonded insulated rail joint to simulate the weight of a train passing on it. The effects of the suspended and supported placement of sleepers, the thickness and Poisson’s ratio of epoxy, and the length of joint bar on the stress distributions at the interfaces between steel rail and epoxy were evaluated numerically. Numerical results show that the interfacial stresses at the boundaries between steel rail and epoxy can be effectively reduced when the supported placement of sleepers is employed as compared to the suspended placement of sleepers. The interfacial tensile stress at the bottom part of the bonded insulated rail joint under the supported placement of sleepers is increased but the other interfacial stresses are decreased as the thickness of epoxy is increased. When the length of joint bar becomes shorter, the interfacial tensile stress of the bonded insulated rail joint under the supported placement of sleepers is increased significantly but the other interfacial stresses are affected insignificantly. Also, the interfacial stresses of bonded insulated rail joints are higher and more concentrated when the material property of epoxy becomes incompressible.
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Fung, Ho Ching, and 何靜芳. "Rail-Wheel Dynamical Analysis by Appling Theory of Periodically Supported Beam under Moving Loads." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/57494240749438010614.
Full textAbstract:
碩士國立海洋大學
系統工程暨造船學系
89
The aim of this thesis is to establish the theoretical model of the rail-wheel interaction and the induced vibrations. The dynamic analyses regarding all kinds of the existing rail and train in our country have been carried out. The rail on the equidistant sleepers can be considered as a periodically supported beam. Using the theory of rail-wheel interaction, the analyses of the diversely dynamic responses of the train wheels and rails which are installed by the Taiwan Railway, the Taiwan Rapid Transit and the Taiwan High Speed Rail etc., are undertaken. Besides, the effect of damping material on the vibration and noise attenuation of the rail of Taipei Rapid Transit, has been characterized. Comparison of the vibration responses by the software-simulation and the experimental measurement to the rail entity, has been made to ascertain the optimal design of the countermeasure in using the damping layer technique. The model analysis and harmonic analysis of the rails and wheels are undertaken by the finite element analysis software ANSYS. Firstly, the natural frequencies of and the relevant natural modes of each pair of wheels and rail are obtained by the Modal Analysis. Then, the receptance function representing the vibration transmission behavior from a driving point with unit harmonic force to a receiving point can be analyzed by the Harmonic Analysis. Regarding to the dynamic responses of each mechanical components of a moving train such as car body, bogie and rail, the software ADAMS, i.e., Automatic Dynamic Analysis of Mechanical Systems , developed by Mechanical Dynamic Incorporated track systems, is used to perform the analysis for the cases of different rail track systems and different moving velocities of train. Also, the influences of train creepage and rail roughness on the interaction at the contacting point between rail and wheel and the derailment quotient are discussed. In addition, to discuss the radiating noise from a moving train, the software TWINS,i.e.,Track-Wheel Interaction Noise Software, which is developed by the European Rail Research Institute and some related groups for low noise tracks systems, is applied to analyse the source and discuss to the related remedy measures for the noise. In the process of the analysis, the sound power of the exciting source point and the radiated sound pressure at some specified location in the system can be attained. Meanwhile, the dynamic characteristics like the receptances, the wave number, and the relevant properties system can be obtained as well.
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Chen, Wei-Yeh, and 陳暐曄. "Stress Analysis of Scooter Frames and Rear-Wheel Suspension Systems." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/12029348952216291473.
Full textAbstract:
碩士義守大學
機械與自動化工程學系碩士班
98
Scooters are important vehicles in Taiwanese society. We can see lots of scooters on the roads everywhere in Taiwan. Although Taiwan has the highest scooter density in the world, not many people have a basic understanding of this main transportation vehicle. The major types of scooter rear suspension configuration available in the market are the single-shock suspension type and the twin-shock suspension type. However, there is no specific criterion to regulate the suspension configurations which are applied under different circumstances. This thesis utilizes one of the most popular CAD (Computer-Aided Design) and CAE (Computer-Aided Engineering) application software nowadays in drawing and analyzing the rear suspension configurations. Through simulations and cross-comparisons with various values of parameters ( weight-bearing, shock absorbers spring constant, shock absorbers span width, etc), we try to find out the differences between the above two configurations on stress and fatigue analysis.
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MARINI, LORENZO. "Development and Experimental Validation of Innovative Models to Predict Wheel and Rail Wear on Complex Railway Networks." Doctoral thesis, 2014. http://hdl.handle.net/2158/854499.
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wei-renn, Chen, and 陳威任. "Geometry design and stress analysis of aluminum alloy wheel under bending load." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/93657153741389675766.
Full textAbstract:
碩士明志科技大學
機電工程研究所
99
In this thesis, the geometry design and stress analysis of the aluminum alloy wheel have been accomplished. The CAD/CAE softwares SolidWorks and ANSYS are adopted in this study. The bending conditions applied on the wheel obey the SAE rules. Using the finite element analysis, five cases of the 15-inch aluminum wheel have been analyzed. As a result, the Case-5 wheel has good performance for the strength and weight. Its maximum von Mises stress is 142.59 MPa so that the safety factor is enough. By the weight-reduction design process, the mass of Case-5 is reduced to 6.8 kg.
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Tangtragulwong, Potchara. "Optimal Railroad Rail Grinding for Fatigue Mitigation." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8909.
Full textAbstract:
This dissertation aims to study the benefit of rail grinding on service life of railroad rails, focusing on failures due to rolling contact fatigue (RCF) at the rail head. Assuming a tangent rail with one-point contact at the running surface, a finite element analysis of a full-scale wheel-rail rolling contact with a nonlinear isotropic kinematic hardening material model is performed to simulate the accumulation of residual stresses and strains in the rail head. Using rolling stress and strain results from the sixth loading cycle, in which residual stresses and strains are at their steady-state, as input, two critical plane fatigue criteria are proposed for fatigue analyses. The first fatigue criterion is the stress-based approach—namely the Findley fatigue criterion. It suggests an important role of tensile residual stresses on subsurface crack nucleation and early growth in the rail head, but applications of the criterion to the near-running-surface region are limited because of plastic deformation from wheel-rail contact. The second fatigue criterion is the strain-based approach—namely the Fatemi-Socie fatigue criterion. Contributed mainly from shear strain amplitudes and factorized by normal stress components, the criterion also predicts fatigue crack nucleation at the subsurface as a possible failure mode as well as fatigue crack nucleation at the near-surface, while maintaining its validity in both regions. A collection of fatigue test data of various types of rail steel from literature is analyzed to determine a relationship between fatigue damages and number of cycles to failure. Considering a set of wheel loads with their corresponding number of rolling passage as a loading unit (LU), optimizations of grinding schedules with genetic algorithm (GA) show that fatigue life of rail increases by varying amount when compared against that from the no-grinding case. Results show that the proposed grinding schedules, optimized with the exploratory and local-search genetic algorithms, can increase fatigue life of rail by 240 percent. The optimization framework is designed to be able to determine a set of optimal grinding schedules for different types of rail steel and different contact configurations, i.e. two-point contact occurred when cornering.
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(9841550), Md Uddin. "Development of wayside rail curve lubrication model for Australian heavy haul lines." Thesis, 2016. https://figshare.com/articles/thesis/Development_of_wayside_rail_curve_lubrication_model_for_Australian_heavy_haul_lines/13387283.
Full textAbstract:
Wheel and rail wear and ineffective lubrication are serious concerns for rail operators around the globe. These assets have to be maintained and operated effectively to maximise the benefits to the stakeholders and minimise the cost to rail operators. Proper management of the wheel/rail interface helps the rail industry to grow business, improve reliability of service and commitment to their clients. Rail wear and effectiv lubrication are significant issues that have direct impact on operating costs of the rail operation. Wear causes detrimental effects on rail/wheel life and maintenance costs. Thus a better understanding of causes, mechanisms and effects of wear at the wheel/rail interface is necessary. Lubrication is considered as one of the most effective maintenance programs to reduce wear, energy consumption and noise.
Therefore, implementation of an effective lubrication program is necessary to achieve cost effective rail operation.
The wayside lubrication method is widely used in the rail industry. In the past, lubricators were installed either too close together or too far apart. The literature indicates that quite a few approaches have been attempted for developing an effective placement model for wayside lubricators. There are different types of lubricators, lubricants and a variety of
lubrication strategies across different networks, and also within the same network. A critical literature review revealed that there is a need for a more scientific approach to develop a reliable rail curve lubrication model. Keeping this fact in view, field investigations were carried out on the live track in the current study with the assistance of maintenance team of
the Australian heavy haul network operators. The first observation revealed that the grease carried by the wheels lasts only a few meters from the wayside lubricator sites in many curves. The performance of lubricants in the track can vary significantly depending on the weather conditions, track characteristics, dispensing equipment, type of lubricant being used and maintenance activities. In this field study it is clearly identified that there is a need for an improved understanding of the effect of lubricator performance, applicator bars (short and long bars) and locations of the bars based on track geometry, direction of traffic etc. Proper application of wayside lubricators also includes selection of appropriate equipment and a suitable lubricant for the known operating conditions, measurement and management of the lubrication effectiveness, positioning of lubricators and their appropriate maintenance.
Wayside lubricator spacing for maximum benefits is directly related to the lubricant carry distance. Whereas, carry distance is affected by track type, traffic, lubricant and the lubricator itself. Hence, there is a clear need to develop an improved lubricator placement model based on the combined effects of lubricants, applicator bars, lubricator, locations and track/traffic
characteristics. The scope of this study also includes the survey of the current practices of curve lubrication and assesses their effectiveness; develop a hierarchical wayside lubricator placement model based on the evaluation of effectiveness and cost/benefit analysis and set up a standard practice for lubrication of heavy haul lines. A detailed review on currently available technologies applicable for heavy haul lines was performed. This was followed by the field investigations for real data collection to confirm the performance evaluation, development of lubricator placement model, cost/benefit analysis, model development of the grease transport mechanism, and optimisation of modelled parameters. The study concluded that electric lubricators are highly reliable and effective compared to older technologies, long applicator bars in the tangent track with high quality grease generate the longest carry distances and short applicator bars in the transition curve, even with high quality grease, didn't achieve long carry distances.
The rate of grease application is very crucial from the perspective of both effectiveness and economic returns. It is also known that equipment, their limitations, performance, appropriate location, quality of installation and their maintenance, various properties of greases and column strength of the grease bead contribute significantly to the grease transport mechanism. This study suggests that to ensure the effectiveness of way side curve lubrication, remote condition monitoring could be an effective tool which can significantly improve the reliability, maintainability and operating cost of electric lubricators.
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Marques, Pedro Filipe Lima. "Modeling complex contact mechanics in railway vehicles for dynamic reliability analysis and design." Doctoral thesis, 2020. http://hdl.handle.net/1822/77055.
Full textAbstract:
Tese de Doutoramento (Programa Doutoral em Líderes para Indústrias Tecnológicas)O uso de metodologias computacionais para estudar o comportamento dinâmico de veículos ferroviários é cada vez mais comum, pois permite analisar o desempenho do veículo numa dada via, ajudar a projetar sistemas de suspensão, travagem ou tração, estudar o dano dos componentes, entre outros. Neste tipo de ferramentas, a modelação da interação do veículo com a via, traduzindo-se no contacto entre as rodas e os carris, tem particular importância. Posto isto, o presente trabalho visa desenvolver métodos computacionais que permitam uma análise mais detalhada do contacto propondo avanços relativos aos métodos existentes na literatura. Para a deteção de contacto entre a roda e o carril, foi desenvolvida uma abordagem tridimensional para identificação dos pontos de maior interferência, na qual as geometrias da roda e do carril são definidas como superfícies paramétricas. Este método tira partido do facto de a roda ser um corpo de revolução e o carril uma superfície de arrastamento, permitindo identificar o contacto entre perfis gerais, sem a necessidade recorrer a simplificações que evitem a existência de uma zona côncava na roda, isto é, permite a abordagem de contacto entre superfícies conformes. Nas abordagens atuais ao problema do contacto roda-carril, assume-se que a área de contacto é plana, contudo, essa hipótese deixa de ser válida para contactos onde exista alguma conformidade. Nesse sentido, foi desenvolvida uma metodologia para a determinação de uma zona de contacto curva em que a direção normal à superfície de contacto varia ao longo da mesma. Este método permite evitar descontinuidades no cálculo das forças de contacto normais como é aqui demonstrado em diversos casos de teste para o contacto estático entre rodas e carris. A avaliação das forças de contacto tangencial é determinante na interação roda-carril, sendo aqui proposta a utilização de tabelas de pesquisa para o cálculo dessas forças para permitir a diminuição do tempo de cálculo. Neste caso, uma tabela de procura com cinco varáveis de entrada, que considera uma região de contacto definida por uma dupla elipse, é utilizada para estudar o erro de interpolação devido à sua discretização. Com a metodologia proposta é possível estudar a exatidão da tabela de pesquisa sendo, neste processo, apresentadas duas versões melhoradas desta tabela, com minimização de erro ou com minimização da sua dimensão. O modelo multicorpo de uma carruagem do Metro de Lisboa é utilizado para demonstrar as metodologias desenvolvidas neste trabalho através da realização de análises dinâmicas em condições de operação. A cinemática do veículo, a localização dos pontos de contacto, as forças de contacto e as variáveis de entrada da tabela de procura são analisados em detalhe. Os resultados mostram que a utilização de perfis de rodas realistas em detrimento de perfis simplificados tem um impacto significativo na dinâmica do veículo e no tipo e número de contactos desenvolvidos. Da mesma forma, o uso de modelos não-Hertzianos para o cálculo das forças de contacto também tem uma influência considerável no comportamento dos veículos ferroviários relativamente às abordagens correntes.
The use of computational tools to study the dynamic behavior of railway vehicles has been increasing due to its wide range of applications, namely to assess the performance of a vehicle in given track, design suspension, traction or braking systems, analyze the damage of components, among others. In this context, the vehicle-track interaction, which consists of the contact between wheels and rails, plays an important role. Thus, the present work aims to develop computational methodologies which allow a more detailed contact modeling presenting advances over the models available on the literature. In what concerns the contact detection between wheel and rail, a three-dimensional approach to identify the main contact points between wheel and rail was established. This methodology treats both geometries as parametric surfaces and takes advantage of the fact that the wheel is a revolution body and the rail is a sweep surface. Moreover, this allows to determine the contact between general surfaces, without using a simplified wheel profile which avoids the concave region, i.e., it treats the contact between conformal surfaces. In the current approaches to deal with wheel-rail contact, a planar contact region is assumed, however, this hypothesis is violated in the presence of conformality. Hence, it was developed a methodology to evaluate a curved contact patch in which the normal direction to the contact surface varies over the contact area. This method avoids discontinuities on the normal contact force evaluation, as demonstrated here through some wheel-rail static cases. The evaluation of tangential contact forces is fundamental in the context of wheel-rail interaction and, in this work, the utilization of lookup tables for the calculation of these forces is proposed for sake of the reduction of calculation time. Thus, a lookup table with five input variables, in which the contact patch is regularized to a simple double-elliptical contact region, is utilized to study the interpolation error due to its discretization. According to the presented methodology, it is possible to study the accuracy of a given lookup table and, in this process, two enhanced versions of this table are presented, one with minimization of the interpolation error and other with minimization of its size. The dynamic analyses of a multibody model of a trailer vehicle from Lisbon subway system in operation conditions are utilized to validate the methodologies developed in this work. The kinematics of the vehicle, the location of the contact points, the contact forces and input variables of the lookup table are analyzed in detail. The results demonstrate that the use of realistic wheel profiles has a significant influence in the dynamic response of the vehicle and in the type of identified contacts. Similarly, it is shown that the utilization of non-Hertzian contact models for the evaluation of both normal and creep forces also influences the dynamics of railway vehicles when compared with current approaches.
Fundação para a Ciência e a Tecnologia (FCT) for funding this work through the PhD grant PD/BD/114154/2016, in the context of MIT Portugal Program.