Simon Iwnicki

Handbook of railway vehicle dynamics

Introduction Simon Iwnicki Aims Introduction to the Aims of Handook Structure of the Handbook A History of Railway Vehicle Dynamics Alan Wickens Introduction Coning and the Kinematic Oscillation Concepts of Curving Hunting and the Empirical Development of the Bogie Interaction between Vehicle and Track Innovations for Improved Steering Carter Wheel-Rail Geometry Matsudaira The ORE Competition Creep The Complete Solution of the Hunting Problem Modern Research on Curving Dynamic Response to Track Geometry Suspension Design Concepts and Optimisation Derailment The Development of Computer Simulation Active Suspensions The Expanding Domain of Rail Vehicle Dynamics References The Anatomy of Railway Vehicle Running Gear Anna Orlova and Yuri Boronenko Main Functions of the Running Gear and Terminology Bogie Components Common Passenger Vehicle Bogie Designs Common Freight Wagon Bogie Designs Common Tram Bogie Designs Principles of Selecting Suspension Parameters Advanced Bogie Designs References Wheel-Rail Contact Jean Bernard Ayasse and Hugues Chollet Introduction The Normal Contact The Tangent Problem Contact Forces in the Railway Context Appendix 4.1: Kinematic Movement: The Klingel Formula Appendix 4.2: Kinematic Hunting and Equivalent Conicity Appendix 4.3: The Circle Theory Appendix 4.4: Analysis of Y/Q and Nadals Criteria Nomenclature References Tribology of the Wheel-Rail Contact Ulf Olofsson and Roger Lewis Introduction Contact Conditions at the Wheel-Rail Contact Wear and Other Surface Damage Mechanisms Friction Lubrication and Surface Coatings Acknowledgments References Track Issues Tore Dahlberg The Railway Track as a Dynamic System Function of the Track Dynamic Properties of the Track Dynamic Properties of Track Components Summary Acknowledgements References Gauging Issues David M. Johnson Philosophy and History of Gauging Components of Gauging Interaction between Gauging Components References Railway Vehicle Derailment and Prevention Huimin Wu and Nicholas Wilson Introduction History and Statistics Railway Vehicle Derailment Mechanisms and Safety Criteria Prediction of Derailment Prevention of Derailment References Longitudinal Train Dynamics Colin Cole Introduction Modelling Longitudinal Train Dynamics Interaction of Longitudinal Train and Lateral/Vertical Wagon Dynamics Longitudinal Train Crashworthiness Longitudinal Comfort Train Management and Driving Practices Conclusions Acknowledgments Nomenclature References Noise and Vibration from Railway Vehicles David Thompson and Chris Jones Introduction Rolling Noise Reducing Rolling Noise Impact Noise Curve Squeal Other Sources of Noise Vehicle Interior Noise Ground-Borne Vibration and Noise Vibration Comfort on Trains References Active Suspensions R.M. Goodall and T.X. Mei Introduction Basics of Active Suspensions Tilting Trains Active Secondary Suspensions Active Primary Suspensions Technology The Long Term Trends Nomenclature References Simulation Oldrich Polach, Mats Berg, and Simon Iwnicki Introduction Modelling Vehicle-Track Interaction Simulation Methods Computer Simulation Dynamics in Railway Vehicle Engineering Conclusions Acknowledgments Nomenclature References Field Testing and Instrumentation of Railway Vehicles Julian Stow and Evert Andersson Introduction Common Transducers Test Equipment Configuration and Environment Data Acquisition Measurement of Wheel and Rail Profiles Track Geometry Recording Examples of Vehicle Laboratory and Field Tests References Roller Rigs Weihua Zhang, Huanyun Dai, Zhiyun Shen, and Jing Zeng Introduction The History of Roller Rigs The Test Technique and Classification of Roller Rigs Examples of Roller Rigs Operation and Results Conclusions References Scale Testing P.D. Allen Introduction A Brief History of Scaled Roller Rigs Survey of Current Scaled Roller Rigs Roller Rigs: The Scaling Problem Scaling Errors Conclusions Acknowledgements References Index

The Manchester Benchmarks for Rail Vehicle Simulation

This volume contains the results of the Manchester Benchmarking exercise for railway vehicle dynamics simulation packages. Five of the main computer packages currently used for this purpose were examined in the exercise and the results are presented in the form of tables and graphs.

Assessing the accuracy of different simplified frictional rolling contact algorithms

This paper presents an approach for assessing the accuracy of different frictional rolling contact theories. The main characteristic of the approach is that it takes a statistically oriented view. This yields a better insight into the behaviour of the methods in diverse circumstances (varying contact patch ellipticities, mixed longitudinal, lateral and spin creepages) than is obtained when only a small number of (basic) circumstances are used in the comparison. The range of contact parameters that occur for realistic vehicles and tracks are assessed using simulations with the Vampire vehicle system dynamics (VSD) package. This shows that larger values for the spin creepage occur rather frequently. Based on this, our approach is applied to typical cases for which railway VSD packages are used. The results show that particularly the USETAB approach but also FASTSIM give considerably better results than the linear theory, Vermeulen–Johnson, Shen–Hedrick–Elkins and Polach methods, when compared with the ‘complete theory’ of the CONTACT program.

Simulation and fault detection of three-phase induction motors

Computer simulation of electric motor operation is particularly useful for gaining an insight into their dynamic behaviour and electro-mechanical interaction. A suitable model enables motor faults to be simulated and the change in corresponding parameters to be predicted without physical experimentation. This paper presents both a theoretical and experimental analysis of asymmetric stator and rotor faults in induction machines. A three-phase induction motor was simulated and operated under normal healthy operation, with one broken rotor bar and with voltage imbalances between phases of supply. The results illustrate good agreement between both simulated and experimental results.

Comparison of wheel–rail contact codes for railway vehicle simulation: an introduction to the Manchester Contact Benchmark and initial results

A new benchmark is being undertaken to assess the impact of wheel–rail contact modelling assumptions on the simulation of railway vehicle dynamics. The benchmark is split into two distinct simulation cases: the first, Case A, using a single wheelset to pinpoint the differences between the contact models and the second, Case B, using a simplified railway vehicle to assess the effect of the different contact models on the simulation of vehicle behaviour. After an open discussion of the Case A specification, the initial call for contributions was made in November 2006. The discussion of simulation Case B specifications was opened in April 2007 and to date is ongoing. This paper briefly introduces the new Manchester Contact Benchmark and presents some of the initial findings from simulation Case A.

Experimental and Theoretical Investigation of Railway Wheel Squeal

Abstract The tangential contact forces that arise at the interface between the wheel of a railway vehicle and the rail provide all the traction, braking, and guidance required by the vehicle. These forces are the result of microslip or creepage and can become unstable exciting vibration of the wheel, particularly at frequencies corresponding to the wheels axial (and radial) modes. Although theories exist for predicting these creep forces and their relationship to creepages, most lack experimental verification in the characterization of the falling friction coefficient during unsteady squealing. This paper presents some new results from a project which aims to develop a complete, validated model of curve squeal noise generation accounting for friction characteristics, excitation due to unstable forces between the wheel and rail and vehicle dynamic behaviour. The model includes wheel and track dynamic response and acoustic radiation. As part of the project, a twin disc rig has been modified to provide experimental data for the validation of the model and measurements were made of the lateral force and dynamic response of the rollers due to varying amounts of lateral creepage during squealing. The main feature of the twin disc rig compared with previous research [1] is that the contact force measuring system measures the contact forces at the web of the rollers and therefore close to the contact patch and through a slipring arrangement enables the lateral vibration of both rollers in relation to squeal be measured with relative ease. In this paper, detailed descriptions of the twin disc rig and the test method developed are given. An outline of the squeal model is also presented. Results from the tests have been compared with the prediction from the squeal model and with available theories and showed good agreement.

A kinetic analysis of trained wheelchair racers during two speeds of propulsion

The purpose of the study was to investigate the propulsion kinetics of wheelchair racers at racing speeds and to assess how these change with an increase in speed. It was hypothesised that propulsive force would increase in proportion to speed, to accommodate the additional work required. Six wheelchair racers volunteered to participate in this study which required each athlete to push a racing wheelchair at 4.70 and 5.64 m s(-1) on a wheelchair ergometer (WERG). Eight pairs (16 in total) of strain gauges, mounted on four bars attached to the hand-rim of a racing wheelchair wheel, measured the medio-lateral and tangential forces applied to the hand-rim. Kinetic data were sampled at 200 Hz while a single on-line (ELITE) infrared camera operating at 100 Hz was positioned perpendicular to the WERG to record the location of the hand with respect to the hand-rim. In general, peak tangential force occurred when the hand was positioned on the hand-rim between 140 and 180 degrees. With the increase in speed, the peak hand-rim forces applied tangentially increased from 132 to 158 N and those applied medio-laterally increased from 90 to 104 N. The ratio of tangential to total measured force was similar at both speeds (80 and 82%, respectively). In conclusion, these data indicate that wheelchair racers adopt a different propulsion strategy than that employed in everyday chairs and that the forces increase in proportion to propulsion speed.

An investigation of sleeper voids using a flexible track model integrated with railway multi-body dynamics

This article describes a flexible track system model (FTSM) that represents the track structure for a typical ballasted track, taking into account the flexibility of the rails, the sleeper mass and the resilience of the pad/fastening elements, as well as the ballast support stiffness condition. The detailed track model is integrated into a commercial railway vehicle dynamics software, thus allowing for any vehicle to be simulated onto the flexible track while at the same time taking into account the detailed calculation of the non-linear wheel—rail contact interaction. As an example, the application of the FTSM to the study of hanging sleepers, with respect to the UK Railway Group Standard limits, is presented. This example shows the impact of forces because of hanging sleepers on the vehicle and on the track, and attempts at quantifying the damage made to the track components for the specific conditions simulated.

The critical speed of a railway vehicle on a roller rig

Abstract The dynamic behaviour of a railway vehicle is largely governed by the interaction of the wheelset with the track. This behaviour can be reproduced in a laboratory using a roller rig and can also be mathematically simulated by solving the equations of motion which govern the dynamic behaviour. This paper presents the results of a study that compares the predictions of these equations of motion for a one-fifth scale railway vehicle on track and on a roller rig. In particular, the critical speed at which the motion first becomes unstable has been shown to differ between the vehicle on track and on the roller rig. It has been shown that for most cases the roller rig case has a lower critical speed but for some suspension parameter combinations the critical speed on the roller rig can be higher.

Validation of a MATLAB railway vehicle simulation using a scale roller rig

SUMMARY A 1/5 scale roller rig has been constructed for use in analysing the dynamic behaviour of railway vehicles. The roller rig includes a servo hydraulic system to allow a realistic input of track irregularities at the rollers and instrumentation is fitted to allow measurement of the position and acceleration of the bodies. This paper reports on the first stage in validating the behaviour of the roller rig using a relatively simple, linear computer model constructed in MATLAB. Initial results show good correlation between the behaviour seen on the roller rig and that predicted by the model.