scholarly journals Investigation of fractures mechanisms of railway axles

2021 ◽  
Vol 62 (1) ◽  
pp. 51-62
Author(s):  
Željko Stojanović ◽  
Božidar Matijević ◽  
Sanja Stanisavljev ◽  
Spasoje Erić
Keyword(s):  
Pitting Corrosion ◽  
Railway Vehicle ◽  
Research Report ◽  
Time Varying ◽  
Paint Coating ◽  
Final Fracture ◽  
Rail Vehicle ◽  
Material Fatigue ◽  
Stress Spectrum ◽  
Critical Damage

The paper gives a systematic overview of literature sources who consider impacts critical damage of mechanical, corrosive and thermal nature which may occur on railway axles during operation and which may be the causes of their fracture. The results of the research of the mechanisms that cause cracks, crack propagation and final fracture of the railway vehicle axle, such as material fatigue and the appearance of localized notches caused by paint (coating) separation, damage from ballast impact and pitting corrosion are presented. The influence of high temperatures and overheating on the axles was analyzed and an excerpt from the research published in one research report was given. Some significant suggestions for optimizing the design of the axles are highlighted which would take into account the analysis of time-varying axle stresses, stress spectrum in operation, axle tolerance to damage and the existence of residual surface stresses. The reliefs of the fracture surfaces of the axle after the railway incidents and the derailment of the rail vehicle from the rails are presented and explained.

scholarly journals Effect of Rail Vehicle–Track Coupled Dynamics on Fatigue Failure of Coil Spring in a Suspension System

2021 ◽  
Vol 11 (6) ◽  
pp. 2650
Author(s):  
Sunil Kumar Sharma ◽  
Rakesh Chandmal Sharma ◽  
Jaesun Lee
Keyword(s):  
Mathematical Model ◽  
Fatigue Fracture ◽  
Suspension System ◽  
Railway Vehicle ◽  
Coil Spring ◽  
Internal Resonances ◽  
Rail Vehicle ◽  
Rail Vehicles ◽  
Stress Result ◽  
Wheel Track

In a rail vehicle, fatigue fracture causes a significant number of failures in the coil spring of the suspension system. In this work, the origin of these failures is examined by studying the rail wheel–track interaction, the modal analysis of the coil springs and the stresses induced during operation. The spring is tested experimentally, and a mathematical model is developed to show its force vs. displacement characteristics. A vertical 10-degree-of-freedom (DOF) mathematical model of a full-scale railway vehicle is developed, showing the motions of the car body, bogies and wheelsets, which are then combined with a track. The springs show internal resonances at nearly 50–60 Hz, where significant stresses are induced in them. From the stress result, the weakest position in the innerspring is identified and a few guidelines are proposed for the reduction of vibration and stress in rail vehicles.

Development of a reduced dynamic model for comfort evaluation of rail vehicle systems

2016 ◽  
Vol 230 (4) ◽  
pp. 489-504 ◽  
Author(s):  
Mortadha Graa ◽  
Mohamed Nejlaoui ◽  
Ajmi Houidi ◽  
Zouhaier Affi ◽  
Lotfi Romdhane
Keyword(s):  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Dynamic Models ◽  
Railway Vehicle ◽  
Passenger Comfort ◽  
Rail Vehicle ◽  
Vehicle System ◽  
Comfort Evaluation ◽  
Complex Models ◽  
Reduced Dynamic

In this paper, an analytical reduced dynamic model of a rail vehicle system is developed. This model considers only 38 degrees of freedom of the rail vehicle system. This reduced model can predict the dynamic behaviour of the rail vehicle while being simpler than existing dynamic models. The developed model is validated using experimental results found in the bibliography and its results are compared with existing more complex models from the literature. The developed model is used for the passenger comfort evaluation, which is based on the value of the weighted root mean square acceleration according to the ISO 2631 standard. Several parameters of the system, i.e., passenger position, loading of the railway vehicle and its speed, and their effect on the passenger comfort are investigated. It was shown that the level of comfort is mostly affected by the speed of the railway vehicle and the position of the seat. The load, however, did not have a significant effect on the level of comfort of the passenger.

scholarly journals Thermal EHL Characteristics Investigation on Axle Box Bearings of Railway Vehicle Based on Slicing Method

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Junzhou Huo ◽  
Jianjun Zhou ◽  
Tao Li ◽  
Zhichao Meng ◽  
Wei Sun
Keyword(s):  
System Dynamics ◽  
Scale Effects ◽  
Contact Load ◽  
Railway Vehicle ◽  
Strong Impact ◽  
Time Varying ◽  
Track System ◽  
Nonlinear Contact ◽  
Slicing Method ◽  
Thermal Ehl

Lubrication failures of axle box bearings can lead to accidents, such as bearing burnout and hot axle cutting. Presently, the modeling of the vehicle-track system dynamics rarely considers the nonlinear contact load of axle box bearings, and this leads to imperfection in the vehicle-track system dynamics calculation. And then, the load distribution and lubrication characteristics of axle box bearings are difficult to obtain. Therefore, in this paper, we fully consider the time-varying nonlinear contact load of bearings and track irregularity in establishing the bearing-wheel-rail system coupling-dynamics model. The dynamic response of axle box bearings is obtained by taking the vertical, strong impact-time-varying load on the carrying saddles as the external excitation. The load-balance equation of dynamic pressure lubrication is then obtained, according to the slicing method of bearing rollers. Finally, the elastohydrodynamic lubrication (EHL) model of axle box bearings is established considering thermal and scale effects. The results show that the central film thickness under thermal EHL was decreased by 13.61% compared with that under isothermal EHL. As the velocity of the contact pair increases, the thickness difference between thermal and isothermal EHL became larger. Thermal effects should be considered in the EHL model, in order to truly reflect the characteristics of EHL under a high speed.

Analysis of generalized force and its influence on ride and stability of railway vehicle

2020 ◽  
Vol 51 (6) ◽  
pp. 95-109
Author(s):  
Rakesh Chandmal Sharma ◽  
Sakshi Sharma ◽  
Sunil Kumar Sharma ◽  
Neeraj Sharma
Keyword(s):  
Potential Energy ◽  
Degrees Of Freedom ◽  
Ride Comfort ◽  
Contact Point ◽  
Railway Vehicle ◽  
Energy Potential ◽  
Dissipation Energy ◽  
Rail Vehicle ◽  
Random Track Irregularities ◽  
Lagrange’S Method

Formulation of a rail vehicle model using Lagrange’s method requires the system’s kinetic energy, potential energy, spring potential energy, Rayleigh’s dissipation energy and generalized forces to be determined. This article presents a detailed analysis of generalized forces developed at wheel–rail contact point for 27 degrees of freedom–coupled vertical–lateral model of a rail vehicle formulated using Lagrange’s method and subjected to random track irregularities. The vertical–lateral ride comfort of the vehicle and the ride index of the vehicle are evaluated based on ISO 2631-1 comfort specifications and stability is determined using eigenvalue analysis. The parameters that constitute the generalized forces and critically influence ride and stability have been identified and their influences on the same have been analysed in this work.

Development and Application of CAD Technology in Railway Vehicle Studying

2014 ◽  
Vol 1037 ◽  
pp. 468-473
Author(s):  
Xu Xu Wang ◽  
Guang Zhong Hu ◽  
Shou Ne Xiao ◽  
Yong Ming Tang
Keyword(s):  
Data Management ◽  
Design Method ◽  
Digital Design ◽  
Current Status ◽  
Railway Vehicle ◽  
Rail Vehicle ◽  
Parametric Data ◽  
Visualization Technology ◽  
Organic Combination ◽  
And Control

The emergence and development of CAD technology, and its development and current status of applied research on rail vehicle in our country is introduced. For four key technologies of CAD on digital design direction of rail vehicles, which are integrated, modular, parametric, data management and control, is discussed detailed. What’s more, the direction of rail vehicle design is referred to, which introduces new innovation of TRIZ, universal design and reconfigurable design in theory, changes reverse engineering to top-down design in the design method, realizes the organic combination of modular and integrated in design platform development, and accelerates basic technology research which contains unstructured data processing technology, non-relational database management technology and visualization technology in data management .

Mechatronic suspension design for full rail vehicle system

2016 ◽  
Vol 231 (4) ◽  
pp. 571-590 ◽  
Author(s):  
Mortadha Graa ◽  
Mohamed Nejlaoui ◽  
Ajmi Houidi ◽  
Zouhaier Affi ◽  
Lotfi Romdhane
Keyword(s):  
Tracking Error ◽  
Linear Quadratic Regulator ◽  
Experimental Result ◽  
Railway Vehicle ◽  
Linear Quadratic ◽  
Rail Vehicle ◽  
Vehicle System ◽  
Frequency Domains ◽  
Rail Irregularities ◽  
Vehicle Motion

In this paper, an analytical mechatronic dynamic design model of a full rail vehicle system is developed. Based on the rail vehicle motion, its degree of freedom can be reduced to only 38. This reduction is necessary for the model simplicity. The developed model is validated with experimental result and compared with other one from literature. The real characteristics of the actuators are discussed, and its controller is designed. A mechatronic model that expresses the controlled tracking error as function of the vehicle dynamics and the actuator characteristics is developed. This model is used by the linear quadratic regulator approach to identify the mechatronic rail vehicle proportional–integral–derivative controller’s gains. The mechatronic rail vehicle comfort is evaluated in terms of the passenger displacement, acceleration and frequency as a response of a rail irregularities caused by a lateral and two vertical track irregularities. The simulations of vibration analysis are obtained in time and frequency domains and compared with railway vehicle status. The robustness of the designed mechatronic rail vehicle is verified by simulations, carried out for the cases of car body mass variations. The results show the effectiveness of the proposed mechatronic rail vehicle design which improves significantly the transportation of passengers.

scholarly journals Modelling of the shape of railway transition curves from the point of view of passenger comfort

2021 ◽  
Vol 60 (4) ◽  
pp. 205-217
Author(s):  
Krzysztof Zboiński ◽  
Piotr Woźnica ◽  
Yaroslav Bolzhelarskyi
Keyword(s):  
High Speed ◽  
Point Of View ◽  
Transition Curve ◽  
Optimum Shape ◽  
Railway Vehicle ◽  
Vehicle Model ◽  
Circular Arc ◽  
Passenger Comfort ◽  
Rail Vehicle ◽  
Transition Curves

In the past, railway transition curves were not used. Instead of it, a simple connection of the straight track and circular arc was applied. Nowadays, such simplicity is not allowed due to the increasing vehicle operating velocities. It is mainly visible in the high-speed train lines, where long curves are used. The article aims to develop a new shape of railway transition curves for which passenger travel comfort will be as high as possible. Considerations in this paper concern the polynomials of 9th- and 11th-degrees, which were adopted to the mathematical model of the mentioned shape of curves. The study's authors applied a 2-axle rail vehicle model combined with mathematically understood optimisation methods. The advanced vehicle model can better assign the dynamical properties of railway transition curves to freight and passenger vehicles. The mentioned model was adopted to simulate rail vehicle movement in both cases of the shape of transition curves and the shape of circular arc (for comparison of the results). Passenger comfort, described by European Standard EN 12299, was used as the assessment criterion. The work showed that the method using the 2-axle railway vehicle model combined with mathematically understood optimisation works correctly, and the optimisation of the transition curve shape is possible. The current study showed that the 3rd-degree parabola (the shape of the curve traditionally used in railway engineering) is not always the optimum shape. In many cases (especially for the long curves), the optimum shape of curves is between the standard transition curves and the linear curvature of the 3rd-degree parabola. The new shapes of the railway transition curves obtained when the passenger comfort is taken into account result in new railway transition curves shapes. In the authors' opinion, the results presented in the current work are a novelty in optimisation and the properties assessment of railway transition curves.

Flexible Wheel/Rail Contact Model for Railway Vehicle Dynamics Without Pre-Calculation

2007 ◽  
Author(s):  
Mohammad Durali ◽  
S. Hassan Salehi ◽  
Mohammad Mehdi Jalili
Keyword(s):  
Vehicle Dynamics ◽  
Contact Forces ◽  
Contact Model ◽  
Railway Vehicle ◽  
Dynamic Problems ◽  
Vehicle Dynamic ◽  
Rail Vehicle ◽  
Rigid Contact ◽  
Contact Situation ◽  
Contact Mechanism

An advanced method using progressive concept of geometrical correspondence is applied to create a new wheel/rail contact model based on virtual penetration theory. The geometry and contact mechanism are solved simultaneously because of the independency in a defined correspondence. The model takes the penetrated profiles of wheel and rail and also associated creeps as inputs, and produces driving contact forces as output. The advantage of this model is that it doesn’t require pretabulation of rigid contact situation. The method allows calculating flexible, non-elliptical, multiple contact patches during integration of the model. Consequently the rails with substructures can vibrate separately from the vehicle in a flexible wheel/rail contact model. The simulation results indicate that this method can be used in various rail vehicle dynamic problems.

Ride comfort of a higher speed rail vehicle using a magnetorheological suspension system

2017 ◽  
Vol 232 (1) ◽  
pp. 32-48 ◽  
Author(s):  
Sunil Kumar Sharma ◽  
Anil Kumar
Keyword(s):  
Ride Comfort ◽  
Suspension System ◽  
Magnetorheological Damper ◽  
Ride Quality ◽  
Railway Vehicle ◽  
Passive Suspension ◽  
Railway Vehicles ◽  
Rail Vehicle ◽  
Passive Suspension System ◽  
Secondary Suspension

In a railway vehicle, vibrations are generated due to the interaction between wheel and track. To evaluate the effect of vibrations on the ride quality and comfort of a passenger vehicle, the Sperling's ride index method is frequently adopted. This paper focuses on the feasibility of improving the ride quality and comfort of railway vehicles using semiactive secondary suspension based on magnetorheological fluid dampers. Equations of vertical, pitch and roll motions of car body and bogies are developed for an existing rail vehicle. Moreover, nonlinear stiffness and damping functions of passive suspension system are extracted from experimental data. In view of improvement in the ride quality and comfort of the rail vehicle, a magnetorheological damper is integrated in the secondary vertical suspension system. Parameters of the magnetorheological damper depend on current, amplitude and frequency of excitations. Three semi-active suspension strategies with magnetorheological damper are analysed at different running speeds and for periodic track irregularity. The performance indices calculated at different semi-active strategies are juxtaposed with the nonlinear passive suspension system. Simulation results establish that magnetorheological damper strategies in the secondary suspension system of railway vehicles reduce the vertical vibrations to a great extent compared to the existing passive system. Moreover, they lead to improved ride quality and passenger comfort.

Parametric Analysis of the Ride Comfort of Indian Railway Vehicle

2021 ◽  
Vol 13 (4) ◽  
Author(s):  
Rakesh Chandmal Sharma ◽  
Sono Bhardawaj ◽  
Mohd Avesh ◽  
Neeraj Sharma
Keyword(s):  
Mathematical Model ◽  
Parametric Analysis ◽  
Degrees Of Freedom ◽  
Ride Comfort ◽  
Rear Wheel ◽  
Railway Vehicle ◽  
Mass System ◽  
Rail Vehicle ◽  
Indian Railway ◽  
The Mathematical Model

This paper focuses to the parametric analysis of Indian Railway Rajdhani (LHB) coach. A suitable mathematical model of 40 degrees of freedom (DOF) is formulated by Lagrangian method. The mathematical model of rail-vehicle is modelled by considering eleven mass system containing of backseat support (without cushion), a seat, a car body, two (front and Rear) bolsters, two (front and Rear) bogie frame and four wheelaxles (front bogie front and rear wheel axles and rear bogie front and rear wheel axles. The vehicle is simulated to travel at speed of 100 km/hr on a tangent track. The results from the simulation are validated by comparing the same with the results from experimental data which is acquired from research designs and standards organization (RDSO), Lucknow (India). The parametric analysis is performed to estimate the effect of different parameters of rail-vehicle on the ride behaviour.

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