Andrzej Chudzikiewicz

Simulation of Rail Vehicle Dynamics in MATLAB Environment

The following paper describes a general conception and realization of a computer package to predict some aspects of dynamic behaviour of railway vehicles. The package consists of three parts, an interactive pre-processor, the analysis program and an interactive post-processor. MATLAB was used as environment for the realization of the package. In recent versions only passenger vehicles, which have a MD 52 (Minden-Deutz) type trucks, can be analysed but the pre- and post-processor have a general form.

ANALYTICAL AND EXPERIMENTAL INVESTIGATION OF LOW FLOOR TRAM DYNAMICS

Summary New trends a tram design is to introduce low floor. This creates new problems related to dynamics of driving, stability of driving, wear of wheel. Low floor trams require bogies with independent wheel. Such bogie kinematics scheme shows a tendency to bigger effect of wear of wheel flange. The aim of presented low floor tram investigations was to describe dynamic properties of structure and their influence on flange wear. The experimental investigations consist of strain measurements in articulation and some kinematic pairs in tram body, displacements using contactless measuring sensors, angle of rotation and some mutual characteristics, which describe vehicle dynamics.

Condition Monitoring System for Light Rail Vehicle and Track

Condition monitoring and fault detection systems are becoming increasingly important in rail vehicles maintenance and operation, ensuring safety and reliability improvement. Light rail systems are not the main target for this trend, because of low operational speed and lower safety factors. Nevertheless public transport operators begin to pay a closer attention to the technical state monitoring of vehicle and track, in order to reduce maintenance cost and increase safety and ride comfort for passengers, which is an important challenge for public transport competitiveness in XXI century. The paper describes the main concept of the innovative on-board condition monitoring system for light rail vehicle and track. Functional requirements, assumptions and procedures are described, as well as the on-board data acquisition unit with necessary transducers, which number, function and technical parameters were optimized during the research phase of the project. The prototype of the presented system is now being tested in normal operating conditions.

Practical Solution of Rail Vehicle and Track Dynamics Monitoring System

The improvement of traveller comfort and safety, in parallel to an increase of passenger train speed, is a reason to implement monitoring systems. These systems are more often used to monitor components of railway infrastructure and vehicles. Studies in this area must be preceded by identification and a complex analysis of the railway vehicle - track system. This allows us to recognise the dynamic properties of the system and then select the appropriate place to install sensors on board the vehicle. This paper presents the results of model studies and a prototype monitoring system which is installed on a passenger electric traction unit. This system is aimed, inter alia, at monitoring the state of train suspension and the detection of some particular track geometric irregularities.

Condition monitoring of railway track systems by using acceleration signals on wheelset axle-boxes

The aim of this paper is to demonstrate the possibilities of estimating the track condition using axle-boxes and car-bodies motions described by acceleration signals. In the paper, the results presented indicate the condition of tracks obtained from the preliminary investigation on the test track. Furthermore, the results from the supervised runs (on Polish Railway Lines) of Electric Multiple Unit (EMU-ED74) with the prototype of track quality monitoring system installed on-board are described. As Track Quality Indicator (TQI) algorithm, used in the mentioned prototype, a modified Karhunen–Loeve transformation is used in preliminary preparation of acceleration signals. The transformation is used to extract the principal dynamics from measurement data. Obtained results are compared to other methods of evaluating the geometrical track quality, namely methods, which apply the synthetic coefficient Jsynth and five parameters of defectiveness W5. The results from the investigation showed that track condition estimation is possible with acceptable accuracy for in-service use and for defining cost-effective maintenance strategies. First published online 04 September 2017

Application of Computer Simulation Methods for Running Safety Assessment of Railway Vehicles in Example of Freight Cars

We shall discuss the problem of rail vehicle safety studies using simulation methods. The contemporary methods and criteria used for safety assessment of railway vehicles by railways Europe are shown, whereas special attention is paid to the criteria and research programs applied to the vehicle approval procedures in Poland. Taking advantage of these safety criteria and codes of practice, a number of computer simulations have been conducted in order to study the safety issues. Presented results of the computer simulations include a rail vehicle running on a tangent and curved track for different simulation parameters such as: running velocity, load level, condition of wheel profiles, track irregularities. The track irregularities represent different maintenance quality levels which are set according to UIC518 code. In this paper there has also been made a comparison between the results of computer simulation safety assessment studies and the measurements taken in real conditions during the safety tests of a Shimmns(s) type freight vehicle.

Thermoelastic Wheel - Rail Contact Problem with Temperature Dependent Friction Coefficient

The paper deals with the numerical solution of wheel - rail rolling contact problems. The contact of a rigid wheel with an elastic rail resting on a rigid foundation is considered. The friction between the bodies is assumed to be described by the Coulomb law. Moreover, due to friction, the heat generation and as well as the occurrence of wear are assumed. The wear phenomenon in the contact zone is governed by Archard’s law. This contact problem either as an elastic static problem or a dynamic viscoelastic problem has been investigated by many authors (see [1], [3]). In literature this problem was solved assuming constant friction coefficient. Numerous experiments indicate [2] that at least in the range of higher temperatures the friction coefficient decreases with the increase of the temperature. This paper is concerned with this rolling contact problem where the friction coefficient is assumed to be piecewise linearly dependent on the temperature. The quasistatic approach [1] to solve this contact problem is used. This approach is based on the assumption that for the observer moving with the rolling body the displacement of the supporting foundation is independent on time. The bodies in contact are described by the coupled elliptic variational inequality governing the displacement field and Poisson equation governing the heat flow. To solve numerically this system we will decouple it into mechanical and thermal parts. Using duality theory approach and the regularized relation between tangent and normal components of the contact stress we formulate the mechanical part of this problem as an optimization problem with respect to the normal contact stress. Conjugate gradient method combined with Newton method are used to solve numerically this optimization problem. Next for the calculated displacement field the wear zone is calculated and the thermal part of the system is solved. Numerical examples are provided and discussed. The changes of the temperature distribution and the wear zone due to change of the friction coefficient are reported.

ANALYSIS OF PARAMETRIC SENSITIVITY OF THE MATHEMATICAL MODELS THAT DECRIBE LATERAL DYNAMICS OF A RAILWAY VEHICLE

SUMMARY In the present paper the investigation on parametric sensitivity of the mathematical model has been considered. The model describes lateral dynamics of a railway vehicle for example the coal wagon.