Theoretical Comparison Between Different Configurations of Radial and Conventional Bogies

This article compares the dynamic behaviour of different configurations of radial and conventional two-axle bogies. In general, the design parameters for a better curve negotiation are not compatible with those for good stability. As the main target of this article is to compare the curving performances of different bogies under the same design basis, several bogie configurations with the same level of stability, obtained by choosing proper primary suspension stiffnesses, have been used. The comparison includes a conventional bogie and three radial bogies with differing self-steering and forced-steering principles in three different passenger services: High Speed, Regional and Mass Transit. The analysis has been concentrated on parameters such as stability, lateral wheel-track forces in curve and wheel wear indices. The results show that the radial bogie configurations studied do not make significant contributions in general applications with regard to a conventional bogie. It is only under specific running conditions and types of service that some radial bogie configurations provide advantages with respect to the conventional bogie.     

Comparative stability of bogie vehicles with passive and active guidance as influenced by friction and traction

The stability of four bogie configurations is considered for a range of friction coefficients and traction ratios. The basis of comparison is the vehicle with conventional solid-axle railway wheelsets mounted in bogies with relatively stiff plan-view suspension. As improved performance of the wheelset in guidance can be achieved with various forms of passive and active guidance, bogies with yaw relaxation, with conventional wheelsets and active stabilisation and with independent wheels and active guidance are considered. Stability of each of these configurations is studied using a full nonlinear solution of the equations of motion. It is shown that the stability of the passive bogie configurations is very robust in the presence of traction and braking and variations of friction and that this is also true for an actively guided bogie with independent wheels. However, for a bogie with conventional wheelsets and active stabilisation, creep saturation effects can reduce stability significantly.     

Simulation of active steering control for curving under traction in hauling locomotives

Active steering control in the form of secondary yaw control (SYC) and actuated wheelset yaw (AWY) have been in prototype development. This paper presents a new active steering bogie design, actuated yaw force steering (AY-FS), that is able to steer under high traction loads in tight curves. The AY-FS bogie design is compared with the AWY design. The steering performance AWY under high traction loads has not been previously reported. This paper examines five control methods, three for AWY and two for AY-FS bogies and assesses the traction curving and stability control performance of the alternative designs and control methods compared with each other and to passive steering bogie designs. The curving performance results showed considerable advantage in the proposed AY-FS bogies over the AWY. It was shown that control must be applied to both the yaw angle and the steering angle of the bogie to achieve the best traction steering performance which was not possible with the AWY bogies. The proposed new bogie designs of AY-FS overall give better traction curving and stability performance than the AWY designs.     

Simulation of curving at low speed under high traction for passive steering hauling locomotives

The traction control in modern electric and diesel electric locomotives has allowed rail operators to utilise high traction adhesion levels without undue risk of damage from uncontrolled wheel spin. At the same time, some locomotive manufacturers have developed passive steering locomotive bogies to reduce wheel rail wear and further improve locomotive adhesion performance on curves. High locomotive traction loads in curving are known to cause the loss of steering performance in passive steering bogies. At present there are few publications on the curving performance of locomotive steering with linkage bogies. The most extreme traction curving cases of low speed and high adhesion for hauling locomotives have not been fully investigated, with effects of coupler forces and cant excess being generally ignored. This paper presents a simulation study for three axle bogie locomotives in pusher and pulling train positions on tight curves. The simulation study uses moderate and high traction adhesion levels of 16.6% and 37% for various rail friction conditions. Curving performance is assessed, showing forced steering bogies to have considerable advantages over self steering bogies. Likewise it is shown that self steering bogies are significantly better than yaw relaxation bogies at improving steering under traction. As the required traction adhesion approaches the rail friction coefficient, steering performance of all bogies degrades and yaw of the bogie frame relative to the track increases. Operation with excess cant and tensile coupler forces are both found to be detrimental to the wear performance of all locomotive bogies, increasing the bogie frame yaw angles. Bogie frame pitching is also found to have significant effect on steering, causing increased performance differences between bogie designs.     

Hunting stability analysis of high-speed train bogie under the frame lateral vibration active control

In this paper, we study a multi-objective optimal design of three different frame vibration control configurations and compare their performances in improving the lateral stability of a high-speed train bogie. The existence of the time-delay in the control system and its impact on the bogie hunting stability are also investigated. The continuous time approximation method is used to approximate the time-delay system dynamics and then the root locus curves of the system before and after applying control are depicted. The analysis results show that the three control cases could improve the bogie hunting stability effectively. But the root locus of low- frequency hunting mode of bogie which determinates the system critical speed is different, thus affecting the system stability with the increasing of speed. Based on the stability analysis at different bogie dynamics parameters, the robustness of the control case (1) is the strongest. However, the case (2) is more suitable for the dynamic performance requirements of bogie. For the case (1), the time-delay over 10?ms may lead to instability of the control system which will affect the bogie hunting stability seriously. For the case (2) and (3), the increasing time-delay reduces the hunting stability gradually over the high-speed range. At a certain speed, such as 200?km/h, an appropriate time-delay is favourable to the bogie hunting stability. The mechanism is proposed according to the root locus analysis of time-delay system. At last, the nonlinear bifurcation characteristics of the bogie control system are studied by the numerical integration methods to verify the effects of these active control configurations and the delay on the bogie hunting stability.     

Dynamics of Automated Guideway Transit Vehicle with Single-axle Bogies

Summary The steering type of a mechanical guidance system has been used for Automated Guideway Transit (AGT) system in Japan. Recently, the single-axle bogie system has developed for AGT vehicle and applied to Yurikamome 7200 type vehicle. This paper describes dynamic characteristics of AGT vehicle with single-axle bogies. Introducing a nonlinear, 15 degree-of-freedom dynamic model, a computer simulation study on the lateral motion of the AGT vehicle with single-axle bogies are carried out. In order to show the dynamic characteristics of the single-axle bogie clearly, it is compared to that of the AGT vehicle with conventional steering system. The simulation study with actual vehicle parameters shows that single-axle bogie has suitable characteristics for AGT system. The multi-body dynamics modeler, DADS, is used to build the dynamic model of AGT vehicle with single-axle bogies and this is used to demonstrate the vehicle motion in actual guideway. Obtained results are compared to that of the field test. It is shown that the vehicle dynamic response can be obtained in realistic situation by using multibody dynamics code, that is useful for designing both vehicle and guideway.     

Dynamics of Automated Guideway Transit Vehicle with Single-axle Bogies

Summary The steering type of a mechanical guidance system has been used for Automated Guideway Transit (AGT) system in Japan. Recently, the single-axle bogie system has developed for AGT vehicle and applied to Yurikamome 7200 type vehicle. This paper describes dynamic characteristics of AGT vehicle with single-axle bogies. Introducing a nonlinear, 15 degree-of-freedom dynamic model, a computer simulation study on the lateral motion of the AGT vehicle with single-axle bogies are carried out. In order to show the dynamic characteristics of the single-axle bogie clearly, it is compared to that of the AGT vehicle with conventional steering system. The simulation study with actual vehicle parameters shows that single-axle bogie has suitable characteristics for AGT system. The multi-body dynamics modeler, DADS, is used to build the dynamic model of AGT vehicle with single-axle bogies and this is used to demonstrate the vehicle motion in actual guideway. Obtained results are compared to that of the field test. It is shown that the vehicle dynamic response can be obtained in realistic situation by using multibody dynamics code, that is useful for designing both vehicle and guideway.     

Wear/comfort Pareto optimisation of bogie suspension

Pareto optimisation of bogie suspension components is considered for a 50 degrees of freedom railway vehicle model to reduce wheel/rail contact wear and improve passenger ride comfort. Several operational scenarios including tracks with different curve radii ranging from very small radii up to straight tracks are considered for the analysis. In each case, the maximum admissible speed is applied to the vehicle. Design parameters are categorised into two levels and the wear/comfort Pareto optimisation is accordingly accomplished in a multistep manner to improve the computational efficiency. The genetic algorithm (GA) is employed to perform the multi-objective optimisation. Two suspension system configurations are considered, a symmetric and an asymmetric in which the primary or secondary suspension elements on the right- and left-hand sides of the vehicle are not the same. It is shown that the vehicle performance on curves can be significantly improved using the asymmetric suspension configuration. The Pareto-optimised values of the design parameters achieved here guarantee wear reduction and comfort improvement for railway vehicles and can also be utilised in developing the reference vehicle models for design of bogie active suspension systems.     

Multiobjective optimisation of bogie suspension to boost speed on curves

To improve safety and maximum admissible speed on different operational scenarios, multiobjective optimisation of bogie suspension components of a one-car railway vehicle model is considered. The vehicle model has 50 degrees of freedom and is developed in multibody dynamics software SIMPACK. Track shift force, running stability, and risk of derailment are selected as safety objective functions. The improved maximum admissible speeds of the vehicle on curves are determined based on the track plane accelerations up to 1.5?m/s². To attenuate the number of design parameters for optimisation and improve the computational efficiency, a global sensitivity analysis is accomplished using the multiplicative dimensional reduction method (M-DRM). A multistep optimisation routine based on genetic algorithm (GA) and MATLAB/SIMPACK co-simulation is executed at three levels. The bogie conventional secondary and primary suspension components are chosen as the design parameters in the first two steps, respectively. In the last step semi-active suspension is in focus. The input electrical current to magnetorheological yaw dampers is optimised to guarantee an appropriate safety level. Semi-active controllers are also applied and the respective effects on bogie dynamics are explored. The safety Pareto optimised results are compared with those associated with in-service values. The global sensitivity analysis and multistep approach significantly reduced the number of design parameters and improved the computational efficiency of the optimisation. Furthermore, using the optimised values of design parameters give the possibility to run the vehicle up to 13% faster on curves while a satisfactory safety level is guaranteed. The results obtained can be used in Pareto optimisation and active bogie suspension design problems.     

Design of an optimised wheel profile for rail vehicles operating on two-track gauges

This article sets out an optimum synthesis methodology for wheel profiles of railway vehicles in order to secure good dynamic behaviour with different track configurations. Specifically, the optimisation process has been applied to the case of rail wheelsets mounted on double-gauge bogies that move over two different gauges, which also have different types of rail: the Iberian gauge (1668 mm) and the International Union of Railways (UIC) gauge (1435 mm). Optimisation is performed using Genetic Algorithms and traditional optimisation methods in a complementary way. The objective function used is based on an ideal equivalent conicity curve which ensures good stability on straight sections and also proper negotiation of curves. To this end, the curve is constructed in such a way that it is constant with a low value for small lateral wheelset displacements (with regard to stability), and increases as the displacements increase (to facilitate negotiation of curved sections). Using this kind of ideal conicity curve also enables a wheel profile to be secured where the contact points have a larger distribution over the active contact areas, making wear more homogeneous and reducing stresses. The result is a wheel profile with a conicity that is closer to the target conicity for both gauges studied, producing better curve negotiation while maintaining good stability on straight sections of track. The article shows the resultant wheel profile, the contact curves it produces, and a number of dynamic analyses demonstrating better dynamic behaviour of the synthesised wheel on curved sections with respect to the original wheel.     

Finite-element model calibration of a railway vehicle based on experimental modal parameters

This article describes the experimental calibration of a three-dimensional numerical model of an Alfa Pendular train vehicle based on modal parameters. The dynamic tests of the carbody and bogie of the vehicle allowed the determination of the frequencies and modal configurations of 13 vibration modes, by applying the data-driven stochastic subspace identification method. In addition, a dynamic characterisation test of the passenger-seat system was also conducted. The calibration of the model was performed using a submodelling/multistep approach involving two phases, the first one focused on the calibration of the model of the bogie under test conditions and the second one focused on the calibration of the complete model of the vehicle. The calibration was performed through an iterative method based on a genetic algorithm and allowed to obtain optimal values of 17 parameters of the numerical model. For the pairing of the vibration modes, real and complex, a recent technique was used based on the calculation of the modal strain energy. The stability of a significant number of parameters considering different initial populations demonstrated the robustness of the algorithm. The comparison of experimental and numerical responses before and after calibration revealed significant improvements in the numerical model and a very good correlation between the responses obtained with the calibrated model and the experimental responses.     

Conceptual design of high-speed semi-low-floor bogie for train-tram

Train-tram railway vehicles implement the connection between urban tramlines and the surrounding railway network. Train-tram railway vehicles, which use existing infrastructure, can help to avoid large investments in new railways or tramlines and make interchanges between city center and surrounding cities unnecessary. However, present train-tram rail vehicle cannot carry out the integration of operating by means of high speed in intercity railways with operating on small radius of curvature in inner city tramlines. This paper aims to develop a new model for solid wheelsets train-tram railway vehicles, which will not only pass the curve of 25mR radius of curvature traveling on inner city tramlines with the speed of 18 km/h, but also can travel on straight railway with 200 km/h high speed between intercity. In this paper, a new train-tram model, including five car-body and five motor bogies with ten traction motors, is addressed. Expect as a real rail vehicle testing, this study prefer virtual simulation, which is an effective way to show the rail vehicle performance, such as ride stability, ride comfort and ride safety, by means of evaluating the dynamic characteristics of rail vehicle. Moreover, Design of Experiment (DOE) method is used to optimize solid wheelsets bogie system on improving passenger comfort, safety and stability of train-tram. Parameters of components of bogie system are tuned to minimize the derailment coefficient and the ride comfort index. The results shows that the best comfort index for passenger and minimum derailment coefficient are found. The results also show that this optimized new train-tram model is reliable and practical enough to be applied on real rail vehicle design.     

铁路重载货车转向架技术应用探究

铁路重载货车转向架为铁路重载运输提供保障。由于铁路重载货车的重载质量不断增加,运行的速度越来越快速,从而造成了轮轨的损坏,这就需要加强对转向架技术的深入研究。对我国铁路重载货车转向架技术发展的历程进行阐述,详细分析了铁路重载货车转向架技术的应用,并对铁路重载货车转向架的发展趋势进行阐述。     

Dynamic simulations of the freight three-piece bogie motion in curve

A loaded freight vehicle with two three-piece bogies is modelled using the accessible mathematical software MATLAB. The results are compared with its corresponding ADAMS/Rail dynamic multibody simulation model, where similar derailment factors are encountered for the freight vehicle. Both models reveal that the possibility of derailment increases immediately after entering and at the end of the curve – signifying the beginning and the end of the curve as two major points for derailment. Although a three-piece bogie construction is rather simple, its mathematical model proves to be very complex and is nonlinear due to the reported frictional contact at the rail/wheel interface as well as the friction wedges. This research is stimulated by bogie derailments that have occurred in the Iranian railways as well as those in the rest of the world.     

A semi-active control suspension system for railway vehicles with magnetorheological fluid dampers

The high-speed train has achieved great progress in the last decades. It is one of the most important modes of transportation between cities. With the rapid development of the high-speed train, its safety issue is paid much more attention than ever before. To improve the stability of the vehicle with high speed, extra dampers (i.e. anti-hunting damper) are used in the traditional bogies with passive suspension system. However, the curving performance of the vehicle is undermined due to the extra lateral force generated by the dampers. The active suspension systems proposed in the last decades attempt to solve the vehicle steering issue. However, the active suspension systems need extra actuators driven by electrical power or hydraulic power. There are some implementation and even safety issues which are not easy to be overcome. In this paper, an innovative semi-active controlled lateral suspension system for railway vehicles is proposed. Four magnetorheological fluid dampers are fixed to the primary suspension system of each bogie. They are controlled by online controllers for enhancing the running stability on the straight track line on the one hand and further improving the curving performance by controlling the damper force on the other hand. Two control strategies are proposed in the light of the pure rolling concept. The effectiveness of the proposed strategies is demonstrated by SIMPACK and Matlab co-simulation for a full railway vehicle with two conventional bogies.     

Rotational Resistance Behavior and Field Testing of Two-Axle Bogie Design

The bogie, when rotated relative to the car body develops the rotational resistance factor. This will be confirmed by testing under different loading conditions and air springs inflated and deflated in all conditions. Under the most extreme roll, EMU (Electrical Multiple Unit) shall not violate the kinematics envelope. The present article will utilize the multi-body program, MEDYNA, to study the rotational resistance factor in bogie design, as applied to both inflated and deflated air springs. Meanwhile the unique characteristics of a bogie is examined and confirmed through rotating resistance test.     

Unconventional Bogie Designs - Their Practical Basis and Historical Background

This paper deals with the design concepts for steerable bogies. A brief historical background is given and the modern design basis generated by the creep theory is summarised with regard to curving performance and dynamic stability of two- and three-axle bogies. The basic structural elements used for trailing and motorised steerable bogies are illustrated. Experience gained with some recent designs of self-steering and forced-steering bogies is discussed and achievable stability and curving performances are quoted.     

Stability of Freight Vehicles with the H-Frame 2-Axle Cross-Braced Bogies. Simplified Theory

The cross-bracing applied to 2-axle freight bogies compromises the trade-off between curving and stability on a higher level, from the point of view of vehicle dynamic properties, than is possible to achieve with classical structure. This paper presents a simplified theory of stability for a vehicle with H-frame cross-braced bogies. Application of this theory to preliminary design studies involves simple calculations. The results of calculations in the form of stability regions are instructive and help in understanding the problem. This theory does not claim to be comprehensive but it can be useful for preliminary design studies.     

Robustness analysis of bogie suspension components Pareto optimised values

Bogie suspension system of high speed trains can significantly affect vehicle performance. Multiobjective optimisation problems are often formulated and solved to find the Pareto optimised values of the suspension components and improve cost efficiency in railway operations from different perspectives. Uncertainties in the design parameters of suspension system can negatively influence the dynamics behaviour of railway vehicles. In this regard, robustness analysis of a bogie dynamics response with respect to uncertainties in the suspension design parameters is considered. A one-car railway vehicle model with 50 degrees of freedom and wear/comfort Pareto optimised values of bogie suspension components is chosen for the analysis. Longitudinal and lateral primary stiffnesses, longitudinal and vertical secondary stiffnesses, as well as yaw damping are considered as five design parameters. The effects of parameter uncertainties on wear, ride comfort, track shift force, stability, and risk of derailment are studied by varying the design parameters around their respective Pareto optimised values according to a lognormal distribution with different coefficient of variations (COVs). The robustness analysis is carried out based on the maximum entropy concept. The multiplicative dimensional reduction method is utilised to simplify the calculation of fractional moments and improve the computational efficiency. The results showed that the dynamics response of the vehicle with wear/comfort Pareto optimised values of bogie suspension is robust against uncertainties in the design parameters and the probability of failure is small for parameter uncertainties with COV up to 0.1.     

Unconventional Bogie Designs - Their Practical Basis and Historical Background

SUMMARY

This paper deals with the design concepts for steerable bogies. A brief historical background is given and the modern design basis generated by the creep theory is summarised with regard to curving performance and dynamic stability of two- and three-axle bogies. The basic structural elements used for trailing and motorised steerable bogies are illustrated. Experience gained with some recent designs of self-steering and forced-steering bogies is discussed and achievable stability and curving performances are quoted.