Multiobjective Optimization of a Railway Vehicle Dampers Using Genetic Algorithm

2013 ◽  
Author(s):  
Seyed Milad Mousavi Bideleh ◽  
Viktor Berbyuk
Keyword(s):  
Genetic Algorithm ◽  
Multiobjective Optimization ◽  
Dynamic Response ◽  
Ride Comfort ◽  
Lateral Displacement ◽  
Contact Forces ◽  
Design Parameters ◽  
Railway Vehicle ◽  
Level Shift ◽  
Vehicle Speed

Ride comfort, safety, wear and vehicle speed are the most important factors in evaluating the efficiency of railway transportation. In order to decrease the track access charges it is often desirable to run the vehicle at maximum allowed speed, while keeping an admissible amount of wear in system. This usually deteriorates the ride comfort and safety level during the operation. Therefore, an optimization problem to find a tradeoff value for vehicle speed and design parameters is inevitable. Since, ride comfort, safety and wear values are sensitive to primary and secondary suspensions’ damping parameters it is desirable to find the optimum values of such design variables. In this regard, the multiobjective optimization of railway vehicle dampers is considered to increase the cost-efficiency of railway operation. One car vehicle model with 26 degrees of freedom (DOF) along with a set of initial states, design parameters and operational conditions is explored here. All bodies are assumed to be rigid. Vehicle carbody and bogie frames supposed to have the full set of DOF in space. While, only lateral and yaw motions are considered for each wheelset. It is also assumed that wheelset roll angle is a function of the lateral displacement. Primary and secondary suspensions compromised of parallel linear springs and dampers in longitudinal, vertical and lateral directions which connect wheelsets to bogie frames, and bogie frames to carbody, respectively. Lagrange formalism is employed to obtain the system’s equations of motion. The nonlinear heuristic theory is chosen to relate creepages and the corresponding creep contact forces. The dynamic response of the system is obtained for different operational scenarios including ideal and imperfect tangent and curved tracks. Series-based functions are chosen to approximate the harmonic lateral track irregularities. Accelerations at carbody level, shift forces and wear number are used to evaluate the ride comfort, safety and wear, respectively. MATLAB genetic algorithm optimization routine is applied to perform the optimization. The Pareto sets and Pareto fronts obtained from this study provide the vectors of optimal design parameters corresponding to maximum admissible vehicle speed and guarantee the best tradeoff values for safety and comfort with threshold on wear for each operational scenario. Analysis of the obtained results gives insight into multiobjective optimized dynamic response of a railway vehicle and useful hints for designing adaptive bogie systems with the possibility to switch between optimal damping parameters value and provide the best operational efficiency.

Parametric Analysis of Ride Comfort for Tilting Railway Vehicles Running on Irregular Curved Tracks

2016 ◽  
Vol 16 (09) ◽  
pp. 1550056 ◽  
Author(s):  
Yung-Chang Cheng ◽  
Chin-Te Hsu
Keyword(s):  
Ride Comfort ◽  
Lateral Displacement ◽  
Equations Of Motion ◽  
Roll Angle ◽  
Creep Model ◽  
Railway Vehicle ◽  
Vehicle Speed ◽  
Nonlinear Creep ◽  
Rail Irregularities ◽  
Yaw Angle

The ride comfort of a tilting railway vehicle moving on curved tracks with rail irregularities is studied. Using the nonlinear creep model and Kalker's linear theory, the governing differential equations of motion for a tilting railway vehicle running on irregular tracks are first derived. The tilting railway vehicle is modeled by a 27 degree-of-freedom (DOF) car system, considering the lateral displacement, vertical displacement, roll angle and yaw angle of both the wheelsets and bogie frames, as well as the lateral displacement, roll angle and yaw angle of the car body. Based on the international standard ISO 2631-1, the effect of vehicle speed on the ride comfort index of the tilting vehicle is investigated for various tilting angles, using both linear and nonlinear creep models, and various radii of curved tracks, as well as for various suspension parameters. Finally, the ride comfort indices computed with rail irregularities are found to be higher than those with no rail irregularities, indicating that the effect of rail irregularities on the ride comfort of a tilting vehicle cannot be disregarded in practice.

Analysis of the Nonlinear Dynamics of a Railway Vehicle Wheelset

1973 ◽  
Vol 95 (1) ◽  
pp. 28-35 ◽  
Author(s):  
E. Harry Law ◽  
R. S. Brand
Keyword(s):  
Lateral Displacement ◽  
Equations Of Motion ◽  
Vertical Displacement ◽  
Linear Analysis ◽  
Design Parameters ◽  
Railway Vehicle ◽  
Nonlinear Variation ◽  
Constraint Equations ◽  
The Stability ◽  
Nonlinear Equations Of Motion

The nonlinear equations of motion for a railway vehicle wheelset having curved wheel profiles and wheel-flange/rail contact are presented. The dependence of axle roll and vertical displacement on lateral displacement and yaw is formulated by two holonomic constraint equations. The method of Krylov-Bogoliubov is used to derive expressions for the amplitudes of stationary oscillations. A perturbation analysis is then used to derive conditions for the stability characteristics of the stationary oscillations. The expressions for the amplitude and the stability conditions are shown to have a simple geometrical interpretation which facilitates the evaluation of the effects of design parameters on the motion. It is shown that flange clearance and the nonlinear variation of axle roll with lateral displacement significantly influence the motion of the wheelset. Stationary oscillations may occur at forward speeds both below and above the critical speed at which a linear analysis predicts the onset of instability.

Spectral Distribution of Derailment Coefficient in Non-Linear Model of Railway Vehicle–Track System With Random Track Irregularities

2013 ◽  
Vol 8 (3) ◽  
Author(s):  
Ewa Kardas-Cinal
Keyword(s):  
Spatial Frequency ◽  
Second Harmonic ◽  
Lateral Displacement ◽  
Strong Dependence ◽  
Contact Forces ◽  
Railway Vehicle ◽  
Characteristic Structure ◽  
Window Width ◽  
Derailment Coefficient ◽  
Hunting Frequency

Improving the running safety and reducing the risk of derailments are the key objectives in the assessment of the running characteristics of railway vehicles. The present study of the safety against derailment is focused on the effect of wheelset hunting on the derailment coefficient Y/Q and, especially, how it is reflected in the power spectral density (PSD) of Y/Q. The lateral Y and vertical Q forces at the wheel/rail contact are obtained in numerical simulations for a four-axle railway vehicle moving at a constant velocity along a tangent track with random geometrical irregularities. The PSD of Y/Q, calculated as a function of spatial frequency, is found to have a characteristic structure with three peaks for the leading wheelsets and one peak for the trailing wheelsets of the front and rear bogies. The positions of the PSD maxima remain unchanged with increasing ride velocity, while their magnitudes and shapes evolve. One of the PSD peaks occurs for all wheelsets at the same spatial frequency corresponding to the wheelset hunting, while an additional peak at the double hunting frequency is found for the leading wheelsets. Such a peak structure is also found in the PSD of Y/Q determined in simulations with modified parameters of the vehicle primary suspension and for different track sections. The peak at the double hunting frequency is shown, by a detailed analysis of the contact forces, the flange angles and their PSDs, to result from the nonlinear geometry of the wheel/rail contact leading to the second-harmonic term in Y/Q. The emergence of this peak is also closely related to the phase difference between the hunting oscillations of the wheelset lateral displacement and the oscillations of its yaw angle, for which the difference is significantly smaller for the leading wheelset than for the trailing one. Finally, the effect of wheelset hunting is also shown to manifest itself in the strong dependence of the running average of Y/Q, which is used in the railway technical safety standards for the assessment of the safety against derailment (with the Nadal criterion), on the applied window width.

Mathematical Modeling and Multi-Objective Optimization of a Mini-Channel Heat Exchanger Via Genetic Algorithm

2013 ◽  
Vol 5 (3) ◽  
Author(s):  
Tommaso Selleri ◽  
Behzad Najafi ◽  
Fabio Rinaldi ◽  
Guido Colombo
Keyword(s):  
Genetic Algorithm ◽  
Heat Exchanger ◽  
Multiobjective Optimization ◽  
Pareto Front ◽  
Optimization Procedure ◽  
Design Parameters ◽  
Geometrical Parameters ◽  
Objective Functions ◽  
Pressure Drops ◽  
Overall Heat Transfer Coefficient

In the present paper a mathematical model for a mini-channel heat exchanger is proposed. Multiobjective optimization using genetic algorithm is performed in the next step in order to obtain a set of geometrical design parameters, leading to minimum pressure drops and maximum overall heat transfer coefficient. Multiobjective optimization procedure provides a set of optimal solutions, called Pareto front, each of which is a trade-off between the objective functions and can be freely selected by the user according to the specifications of the project. A sensitivity analysis is also carried out to study the effects of different geometrical parameters on the considered functions. The whole system has been modeled based on advanced experimental correlations in matlab environment using a modular approach.

Stability Analysis of High-Speed Railway Vehicle Based on Multibody Dynamics Analysis

2013 ◽  
Vol 392 ◽  
pp. 156-160
Author(s):  
Ju Seok Kang
Keyword(s):  
Stability Analysis ◽  
Multibody Dynamics ◽  
High Speed ◽  
Equations Of Motion ◽  
Contact Forces ◽  
Design Parameters ◽  
Railway Vehicle ◽  
Dynamics Analysis ◽  
Contact Points ◽  
The Stability

Multibody dynamics analysis is advantageous in that it uses real dimensions and design parameters. In this study, the stability analysis of a railway vehicle based on multibody dynamics analysis is presented. The equations for the contact points and contact forces between the wheel and the rail are derived using a wheelset model. The dynamics equations of the wheelset are combined with the dynamics equations of the other parts of the railway vehicle, which are obtained by general multibody dynamics analysis. The equations of motion of the railway vehicle are linearized by using the perturbation method. The eigenvalues of these linear dynamics equations are calculated and the critical speed is found.

Hunting stability analysis of a railway vehicle system using a novel non-linear creep model

2012 ◽  
Vol 226 (6) ◽  
pp. 612-629 ◽  
Author(s):  
Yung-Chang Cheng
Keyword(s):  
Degrees Of Freedom ◽  
Lateral Displacement ◽  
Creep Model ◽  
Railway Vehicle ◽  
Vehicle Speed ◽  
System Parameters ◽  
Proposed Model ◽  
Linear Creep ◽  
Non Linear ◽  
Six Dof

A non-linear creep model that considers non-constant creep coefficients that vary as a function of vehicle speed is derived using Hertz contact theory, Kalker’s linear theory and a heuristic non-linear creep model. The proposed model is created by modifying the heuristic non-linear creep model by adding a linear creep moment and the semi-axis lengths in the non-linearity of the saturation constant. In this paper, the vehicle is modeled by a system with 28 degrees of freedom, taking into consideration the lateral displacement, vertical displacement, roll angle and yaw angle of each wheelset, the truck frames and car body. To analyze the respective effects of the major system parameters on the vehicle dynamics, the 28 degree-of-freedom (DOF) system is reduced to a 25-DOF model, by excluding designated subsets of the system parameters. The accuracy of the present analysis is verified by comparing a six-DOF system and the current numerical results with results in the literature. The effects of suspension parameters of a vehicle on the critical hunting speeds evaluated by the currently proposed model, the traditional non-linear creep model and the linear creep model are illustrated. In most cases, the obtained results show that the critical hunting speed evaluated using the new non-linear creep model is greater than that derived using the traditional non-linear creep model. Additionally, the critical hunting speed evaluated using the linear creep model is higher than that evaluated using the currently proposed non-linear creep model.

Derailment Analysis of High-Speed Railway Vehicle Bogies

2011 ◽  
Vol 110-116 ◽  
pp. 186-195 ◽  
Author(s):  
Yung Chang Cheng ◽  
Chern Hwa Chen ◽  
Che Jung Yang
Keyword(s):  
High Speed ◽  
Lateral Displacement ◽  
Vertical Displacement ◽  
Creep Model ◽  
Railway Vehicle ◽  
Vehicle Speed ◽  
Nonlinear Creep ◽  
Bogie Frame ◽  
Suspension Parameters ◽  
Yaw Angle

Based on the heuristic nonlinear creep model, the nonlinear coupled differential equations of the motion of a 12 degree-of-freedom (12-DOF) bogie system which takes account of the lateral displacement, vertical displacement, the roll angle and the yaw angle of the each wheelset and the bogie frame, moving on curved tracks are derived. The nonlinear creep forces and moments are constructed via the saturation constant of the nonlinear creep model in completeness. The effect of the suspension parameters of a bogie system on the derailment quotient is investigated. Results obtained in this study show that the derailment quotient of a bogie system increases as the vehicle speed increases. In addition, the derailment quotient of a bogie system is generally decreased with the increasing values of suspension parameters.

scholarly journals Research on the influence of virtual modeling and testing–based rubber track system on vibration performance of engineering vehicles

2018 ◽  
Vol 38 (3) ◽  
pp. 288-295
Author(s):  
Guo HaoLiang ◽  
Mu XiHui ◽  
Yang XiaoYong ◽  
Lv Kai
Keyword(s):  
Ride Comfort ◽  
Contact Forces ◽  
Dynamics Simulation ◽  
Vehicle Speed ◽  
Tracked Vehicles ◽  
Track System ◽  
Body Dynamics ◽  
Virtual Modeling ◽  
Difficult Terrain ◽  
Multi Body

The rubber track system can be quickly swapped on the tyres, exerting a smaller ground pressure while generating a greater adhesion to solve the problem vehicles faced in traversing rough and difficult terrain. This paper will discuss the influence of rubber track system on the ride comfort of engineering vehicles with rigid suspension. First, a multi-body dynamic model of the rubber track system and a mathematical model of contact between the ground and the track are established, and then the macro commands are programmed to add many complex contact forces. Moreover, by using the method of physical prototype obstacle testing, the correctness of the simulation model is validated. The ride comfort of the engineering vehicle when equipped with rubber track system is explored by the method of the multi-body dynamics and real vehicle test. The research shows that a flexible roller wheel system can significantly improve the ride comfort of the engineering vehicle when compared to wheeled vehicles. When the vehicle speed is low, the weighted root-mean-square acceleration of the wheeled vehicle and tracked vehicle is almost the same. At the same time, it is verified that the ride comfort of the steel-chain tracked vehicles is worse than that of rubber tracked vehicles, due to the polygon effect. Through the multi-body dynamics simulation of the virtual prototype, we can predict and evaluate the ride comfort of vehicles, saving the cost of testing and obtaining the actual experimental data, which has great significance for the research and development of vehicles.

Object-Oriented Modeling and Simulation of Railway Vehicle Systems

2010 ◽  
Vol 26-28 ◽  
pp. 900-904 ◽  
Author(s):  
Yong He ◽  
Guo Fu Ding ◽  
Yi Sheng Zou ◽  
Mei Wei Jia ◽  
Ming Heng Xu
Keyword(s):  
Software Package ◽  
Ride Comfort ◽  
Object Oriented ◽  
Simulation Software ◽  
Contact Forces ◽  
Railway Vehicle ◽  
Vehicle Systems ◽  
Hunting Stability ◽  
Multi Body ◽  
And Behavior

An object-oriented modeling method was proposed to develop a simulation software package named GVDS which could be used to predict some aspects of dynamic behavior of railway vehicle. The package based on multi-body dynamics mainly consists of three parts, an interactive pre-processor, the solver and an interactive post-processor. With UML, demands and structure of the software package are represented. By modeling of the geometry and behavior of each object, virtual prototype of railway vehicle is formed and by the simulation, the critical speed of hunting stability, wheel-rail contact forces and so on can be determined and the hunting stability, curving behavior and ride comfort can be analyzed and evaluated. Finally, some cases are simulated. The simulation results show the effectiveness of the proposed method.

scholarly journals Influence of Suspension Parameters Changes of a Railway Vehicle on Output Quantities

2019 ◽  
Vol 10 (1) ◽  
pp. 20-29 ◽  
Author(s):  
Ján Dižo ◽  
Miroslav Blatnický ◽  
Stasys Steišūnas ◽  
Gediminas Vaičiūnas
Keyword(s):  
Dynamic Response ◽  
Ride Comfort ◽  
Suspension System ◽  
Railway Vehicle ◽  
Running Safety ◽  
Suspension Parameters ◽  
System A ◽  
Dynamic Analyses ◽  
Computer Analyses ◽  
Important Input

Abstract This article deals with computer analyses of output quantities of a railway vehicle depending on changing of parameters of suspension system. A passenger car was chosen for dynamic analyses. An analysed passenger railway vehicle uses two stage suspension system composed of coil springs and hydraulic dampers. Stiffness of coil springs of primary and secondary suspensions were defined for two states and its influence on output values in terms of quality and quantity was evaluated. As output variables, values of forces in a wheel/rail contact and accelerations in several locations on a wagon body floor were chosen. Values of forces in a wheel/rail contact indicate dynamic response of a railway vehicle running in terms of running safety and values of accelerations serve as important input for evaluation of passenger ride comfort.

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