scholarly journals Optimisation of polynomial railway transition curves of even degrees

2015 ◽  
Vol 35 (3) ◽  
pp. 71-86 ◽  
Author(s):  
Krzysztof Zboiński ◽  
Piotr Woźnica
Keyword(s):  
Simulation Software ◽  
Lateral Acceleration ◽  
Vehicle Body ◽  
Railway Vehicle ◽  
Vehicle Model ◽  
Vehicle Simulation ◽  
Optimisation Methods ◽  
Advanced Model ◽  
Transition Curves

This paper represents new results obtained by its authors while searching for the proper shape of polynomial railway transition curves (TCs). The search for the proper shape means the evaluation of the curve properties based on chosen dynamical quantities and generation of such shape with use of mathematically understood optimisation methods. The studies presented now and in the past always had got a character of the numerical tests. For needs of this work advanced vehicle model, dynamical track-vehicle and vehicle-passenger interactions, and optimisation methods were exploited. In this software complete rail vehicle model of 2-axle freight car, the track discrete model, and non-linear description od wheel-rail contact are used. That part of the software, being vehicle simulation software, is combined with library optimisation procedures into the final computer programme. The main difference between this and previous papers by the authors are the degrees of examinated polynomials. Previously they tested polynomial curves of odd degrees, now they focus on TCs of 6th, 8th and 10th degrees with and without curvature and superelevation ramp tangence in the TC’s terminal points. Possibility to take account of fundamental demands (corresponding values of curvature in terminal points) concerning TC should be preserved. Results of optimisation are compared both among themselves and with 3rd degree parabola. The aim of present article is to find the polynomial TCs’ optimum shapes which are determined by the possible polynomial configurations. Only one dynamical quantities being the results of simulation of railway vehicle advanced model is exploited in the determination of quality function (QF1). This is: minimum of integral of vehicle body lateral acceleration.

scholarly journals Optimization of Polynomial Transition Curves from the Viewpoint of Jerk Value

2017 ◽  
Vol 63 (1) ◽  
pp. 181-199 ◽  
Author(s):  
K. Zboinski ◽  
P. Woznica
Keyword(s):  
Optimization Procedure ◽  
Optimization Methods ◽  
Simulation Software ◽  
Vehicle Model ◽  
Vehicle Simulation ◽  
Numerical Tests ◽  
Full Vehicle ◽  
Freight Car ◽  
Transition Curves ◽  
New Criteria

Abstract The aim of the presented paper is to show the results of shape optimization of railway polynomial transition curves (TCs) of 5th, 7th, and 9th degrees through the use of the full vehicle model and new criteria of assessement concerning the jerk value. The search for the proper shape of TCs means that in this work, the evaluation of TC properties is based on select quantities and the generation of such a shape through the use of mathematically understood optimization methods. The studies presented have got a character of the numerical tests. For this work, advanced vehicle models describing dynamical track-vehicle and vehicle-passenger interactions as well as optimization methods were exploited. In the software vehicle model of a 2-axle freight car, the track discrete model, non-linear descriptions of wheel-rail contact are applied. This part of the software, the vehicle simulation software, is combined with a library optimization procedure into the final computer program.

On the Planning and Construction of Railway Curved Track

2021 ◽  
Vol 13 (2) ◽  
Author(s):  
Sono Bhardawaj ◽  
Rakesh Chandmal Sharma ◽  
Sunil Kumar Sharma ◽  
Neeraj Sharma
Keyword(s):  
High Speed ◽  
Time Derivative ◽  
Railway Track ◽  
Lateral Acceleration ◽  
Transition Curve ◽  
Railway Vehicle ◽  
Geometric Conditions ◽  
Curve Track ◽  
Curved Track ◽  
Transition Curves

Increasing demand for railway vehicle speed has pushed the railway track designers to develop high-quality track. An important measure of track quality is the character of the transition curve track connecting different intersecting straight tracks. A good transition curve track must be able to negotiate the intermittent stresses and dynamic effects caused by changes in lateral acceleration at high speed. This paper presents the constructional methods for planning transition curves considering the dynamics of movement. These methods consider the non-compensated lateral acceleration, deviation in lateral acceleration and its higher time derivatives. This paper discusses the laying methods of circular, vertical and transition curves. Key aspects in laying a curved track e.g. widening of gauge on curves are discussed in this paper. This paper also suggests a transition curve which is effective not only from a dynamic point of view considering lateral acceleration and its higher time derivative but also consider the geometric conditions along with the required deflection angle.

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.

Optimization of Vehicle Handing and Stability Based on RSM

2012 ◽  
Vol 591-593 ◽  
pp. 733-736
Author(s):  
Dong Shan Sun ◽  
Fang Wang ◽  
Yan Pin He
Keyword(s):  
Objective Function ◽  
Simulation Analysis ◽  
Target Function ◽  
Least Square Method ◽  
Linear Interpolation ◽  
Simulation Software ◽  
Least Square ◽  
Lateral Acceleration ◽  
Slip Angle ◽  
Vehicle Model

Based on the theory of multi-body system dynamics and simulation software ADAMS/Car, the whole vehicle model was established. Afterwards by means of pylon course slalom, the accuracy of modeling was tested. The analysis and evaluation were later made to draw a conclusion that the handling stability of model needed improved. So as to improve the handling stability, the index lateral acceleration, yaw rate, side slip angle were taken as target function while suspension stiffness parameters were designed variables. Optimization of vehicle handing stability was practiced by applying second-order Response Surface Methodology (RSM) model. The relationship could be obtained by least square method obviously. Moreover applying with linear interpolation the final objective function was decided. The minimum of final objective function was the optimal result. Simulation analysis was performed again for the whole vehicle model by parameters modification. Subsequently, the results showed that this method greatly improved handling stability.

Establishing design guidelines for compound horizontal curves on three-dimensional alignments

2005 ◽  
Vol 32 (4) ◽  
pp. 615-626 ◽  
Author(s):  
Said Easa ◽  
Essam Dabbour
Keyword(s):  
Three Dimensional ◽  
Design Guidelines ◽  
Simulation Software ◽  
Lateral Acceleration ◽  
Vertical Alignment ◽  
Vehicle Simulation ◽  
Minimum Radius ◽  
Horizontal Curves ◽  
Flat Terrain ◽  
Current Design

In current design guides, the minimum radii of compound horizontal curves are based on the design requirements of simple horizontal curves for each arc on flat terrain. Such a design ignores the effects of compound curvature and vertical alignment. This paper uses computer simulation software to establish the minimum radius requirements for compound curves, considering these effects. The actual lateral acceleration experienced by a vehicle negotiating a two-dimensional (2-D) simple curve is recorded as a base scenario to facilitate the analysis of a compound curve on a flat terrain or combined with vertical alignment (three-dimensional (3-D) compound curves). The vertical alignments examined include upgrades, downgrades, crest curves, and sag curves. Mathematical models for minimum radius requirements were developed for flat and 3-D compound curves. Three types of design vehicles were used. The results show that an increase in the minimum radius ranging from 5% to 26% is required to compensate for the effects of both compound curvature and vertical alignment.Key words: highway geometric design, compound horizontal alignments, side friction, vehicle simulation, 3-D alignments.

The Research of Vehicle Handling Stability Based on ADAMS

2011 ◽  
Vol 127 ◽  
pp. 248-251
Author(s):  
Qiu Fang Zhao ◽  
Tao He ◽  
Wen Juan Xu ◽  
Zhi Qiang Liu
Keyword(s):  
High Performance ◽  
Simulation Software ◽  
Service Performance ◽  
Dynamics Simulation ◽  
Positive Zero ◽  
Vehicle Model ◽  
Simulation Test ◽  
Vehicle Handling ◽  
Vehicle Simulation ◽  
Design Time

With the demand for the high performance, the vehicle handling stability is more and more attractive and becomes one main service performance of modern car. At the same time, traditional calculation method can not meet the requirement of modern automobile research on the analysis of varied performances. The virtual simulation software increases greatly and it is possible to do the vehicle simulation trial. In this paper, a vehicle model of 10-DOF is built by using the dynamics simulation software ADAMS. Through the dynamic simulation test, the vehicle handling stability is studied with emphasis when the S.M. (Static Margin) is positive,zero or negative.The result is a reference in design of the vehicle, so the purpose of saving test funds and shortening design time is achieved.

Modelling, Simulation and Validation of 9 DOF Vehicles Model for Automatic Steering System

2012 ◽  
Vol 165 ◽  
pp. 192-196 ◽  
Author(s):  
Mohd Zakaria Mohammad Nasir ◽  
Khisbullah Hudha ◽  
Mohd Zubir Amir ◽  
Faizul Akmar Abdul Kadir
Keyword(s):  
Autonomous Vehicle ◽  
Steering System ◽  
Simulation Software ◽  
Lateral Acceleration ◽  
Vehicle Model ◽  
Acceptable Error ◽  
Active Safety Systems ◽  
Automatic Steering ◽  
Safety Systems ◽  
Yaw Angle

Autonomous vehicle have recently arouse great interest and attention in the academic worldwide because of their great potential. As the new features for driver assistance and active safety systems are growing rapidly in vehicles, the simulation within a virtual environment has become a necessity. A vehicle model is required to represent the vehicle behaviour as close as real vehicle in simulation software. This paper presents 9 DOF vehicle models which consist of handling and Calspan tire model develop in Matlab Simulink environment to study the vehicle behaviour for double lane change (DLC) and step steer input test. Those criteria will be compared with validated vehicle software namely CarsimEd to evaluated the performance of the vehicle model involving lateral acceleration, yaw angle and yaw rate from both output. Results show the 9 DOF vehicle closely follows the CarsimEd trends with acceptable error at both conditions.

Railway transition curves and the large circular arc radii

2018 ◽  
Vol 121 ◽  
pp. 423-430
Author(s):  
Piotr Woźnica ◽  
Krzysztof Zboiński
Keyword(s):  
Vehicle Body ◽  
Transition Curve ◽  
Optimum Shape ◽  
Function Evaluation ◽  
Vehicle Model ◽  
Mathematical Methods ◽  
Circular Arc ◽  
Vertical Accelerations ◽  
Optimization And Simulation ◽  
Transition Curves

This work concerns the search for the optimum shape of railway transition curves (TCs). In work the authors used mathematical methods of optimization and simulation. The computer simulation concerned the dynamic behavior of the the 2-axle rail vehicle model. As the transition curve the authors adopted a polynomial of degree n, where n=9 and 11. The quality function (evaluation criterion) used concerned vertical accelerations of the vehicle body. The authors used large circular arc radii – R=3000 m and 4000 m. The aim of the research was to find the optimum shapes of the TCs, taking into account the criterion adopted and comparison of them among themselves.

Optimization of railway transition curves for large circular arc radii

2020 ◽  
Vol 129 ◽  
pp. 73-80
Author(s):  
Piotr Woźnica ◽  
Krzysztof Zboiński
Keyword(s):  
Objective Function ◽  
Body Mass ◽  
Current Paper ◽  
Lateral Acceleration ◽  
Vehicle Body ◽  
Circular Arc ◽  
Rail Vehicle ◽  
Transition Curves

The current paper concerns the optimization of the shape of railway transition curves (TCs). As transition curves, the authors used the polynomials of 9th and 11th degree. In the optimization of the shape of the TCs, the model of 2-axle rail vehicle was used. The mentioned objective function concerned the normalised value of the integral of the change of lateral acceleration of vehicle body along the route. The authors used large circular arc radii – R=3000 m and 4000 m. The paper presents the results of the optimization - the types of curvatures of the optimum transition curves and the dynamical courses - the displacements and the accelerations both lateral and vertical of the vehicle body mass centres.

Analysis on Usage Comfort of Highway Based on Lateral Acceleration and Lateral Acceleration Change Rate

2013 ◽  
Vol 427-429 ◽  
pp. 320-324 ◽  
Author(s):  
Zheng Yu Wang ◽  
Cheng Bing Li ◽  
Jin Xu
Keyword(s):  
Rigid Body ◽  
Three Dimensional ◽  
Driver Model ◽  
Lateral Acceleration ◽  
Mountainous Area ◽  
Vehicle Model ◽  
Change Rate ◽  
Vehicle Simulation ◽  
Peak Value ◽  
Made In

To control the lateral acceleration of driving vehicle and its rate of growth is always an important part in road geometric design. At present, vehicles are simplified as single rigid body when and are calculated, moreover, the calculation is made in two-dimensional plane, which does not comply with the actuality. In this article, Road-Driver-Vehicle simulation system (RDVS) is applied to get and of driving vehicle on 3 test roads selected from the mountainous area of southwestern China. In RDVS, the dynamic vehicle model is driven on three-dimensional roads under the control of driver model, so it is more close to the real driving. The results show: got from RDVS is bigger than that from single rigid body calculation. As RDVS is more reliable, from single rigid body calculation may cause an insufficient estimation: suppose the driver drives at the designed speed, though the designed speed varies, the peak value of of the three objects range in [2.0m/s2, 2.5m/s2], beyond the limit of comfort but within tolerable scope; as for subject C without application of clothoid, will exceed the limit of 1.0m/s3. So it is suggested using clothoid, considering improving the quality.

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