Simulation of Influence of Transverse Wheel-Set Movement on Torsion Oscillations

With increasing importance of the railway transport the demands on economic and functional features of the railway traffic increase as well. The features are influenced by many factors, whose identification, direct measuring and impact detection are not easy to obtain in the real service. A computational simulation and a roller rig are suitable means, which enable to recognize an amount of physical limitation influences in conjunction with proposed vehicle construction and with supposed surrounding service conditions make everything clear before a vehicle commissioning. Therefore, the Simulink model, focused on the field of research of traction wheel-sets torsion dynamics and an influence of adhesion conditions, was built, has been used and developed within SGS (Student Grant Competition) and PhD study programs. In the past, the model served for investigation of torsion oscillation excited by changes in torque transfer. In this paper we focus on another source of asynchronous peripheral speed of wheels of a wheel-set. It is given by railway vehicle wheel conicity. It will be shown, how the contact circle diameter change influences the torsion load of the wheel-set axle and the load type.S rostoucím významem kolejové dopravy rostou také nároky na ekonomiku a funkčnost jejího provozu. Ty jsou ovlivňovány řadou faktorů, jejichž identifikace, přímé zjišťování a dopad je v reálném provozu velmi obtížné měřit nebo dlouhodobě sledovat. Počítačová simulace a kladkový stav jsou vhodnými prostředky, kterými lze rozpoznat míru vlivu fyzikálních omezení ve spojení s navrhovanou konstrukcí vozidla a s předpokládanými okolními podmínkami provozu vše vyjasnit před uvedením vozidla do vlastního provozu. Proto byl v rámci SGS (studentská grantová soutěž) a doktorských studijních programů sestaven, používán a rozvíjen model v Simulinku zaměřený na oblast výzkumu torzní dynamiky hnaných náprav a vlivu adhezních podmínek. V minulosti sloužil ke zkoumání torzního kmitání buzeného změnami přenosu krouticího momentu. V tomto článku se zaměřujeme na jiný zdroj asynchronní obvodovou rychlost kol dvojkolí. To je dáno kuželovitostí kol kolejových vozidel. Bude ukázáno, jak změna průměru kontaktní kružnice ovlivňuje torzní zatížení osy dvojkolí a druh zatížení

Research tools aplicable in designing of high-speed and high-power rail vehicles

The importance of the railway transport of both goods and passengers continuously grows as it is in many points of view more ecological and economical solution in comparison with road transport. Just the importance has been supporting efforts to design more powerful and faster trains reaching traction powers more than 1.6 MW per a wheel-set or service top speed much more than 300 km/h till these days. To reach design which has enabled such a kind of performances it was necessary to research dynamic behaviour of railway vehicles. Both via laboratory measurements and simulations. The laboratory experiments have been carried out on a specially designed laboratory equipment called roller rigs. A laboratory equipped by roller rig for testing of the railway vehicle dynamic behaviour has been built at the Faculty of Mechanical Engineering at CTU in Prague, also within PhD studyprograms and SGS grants. Another powerful tool within research activities is a simulation. Kind of a such simulation will be presented by this contribution with the focus on the torsion dynamics of high-power fully-suspended drive of a railway vehicle, which has been developed also by PhD students under financial support of The Faculty of Mechanical Engineering and related grants

Slip and Adhesion in a Railway Wheelset Simulink Model Proposed for Detection Driving Conditions Via Neural Networks

Constantly enlarging operation of locomotives with a very high tractive power in modern railway transport has caused problems with optimal supplying torque from motor to wheel-sets. Losses emerging with inadequate torque values lead to wheel slipping connected with excessive wear and limited acceleration. In models simulating dynamics of torque transmission from the drive units to wheels, the most important are the submodel of the drive and the submodel of balance between traction forces and drive resistances. Some issues of this field studied within a PhD program and SGS (CTU Students Grant Competition) has been focused on increasing quality of these submodels. This contribution is aimed at an innovated part in the existing Simulink model utilizing new data sources and modeling techniques. This improvement supports application of operating point detection methods based on machine learning techniques. New control facilities provided with pulse-width modulated frequency control of the asynchronous motor will be used for automatic submission of optimal operating points. The idea of utilization of via simulation obtained data is an on-line training of polynomial neural unit as an approximation of current driving conditions.Neustále narůstající provoz lokomotiv s velmi vysokým trakčním výkonem v moderní železniční dopravě způsobuje problémy s přenosem optimálního hnacího momentu z motoru na dvojkolí. Ztráty vyplývající z nevhodných hodnot točivého momentu vedou k prokluzu kol spojeným s nadměrným opotřebením a omezeným zrychlením. V modelech simulujících dynamiku přenosu točivého momentu z pohonné jednotky na dvojkolí jsou nejdůležitější submodely pohonu a rovnováhy mezi trakčními silami a jízdními odpory. Výzkum prováděný v rámci doktorských studijních programů a SGS (Studentská grantová soutěž ČVUT) se zaměřuje na zvyšování kvality těchto submodelů. Tento příspěvek je zaměřen na inovovanou část v existujícím Simulink modelu využívajícím nové zdroje dat a technik modelování. Nové možnosti regulace zajištěné pulzně-šířkovou frekvenční regulací asynchronního motoru budou použity pro automatické poskytnutí optimálních provozních bodů. Představa využití simulací získaných dat je on-line učení polynomické neuronové jednotky jako aproximace současných jízdních podmínek

Kalker’s coefficient c11 and its influence on the damping and the retuning of a mechanical drive torsion system of a railway vehicle

Within the research of electromagnetically excited torsion oscillations in the mechanical part of traction drive systems of modern railway vehicles, which has been realized at the Faculty of mechanical engineering at the CTU in Prague, there are two separate simulation models in use. The basic calculation model, which is utilized to gain basic characteristics of the torsion system as natural frequencies and natural modes of oscillations. And the complex simulation model, which simulates a drive of the vehicle. This contribution is focused on the basic calculation model, which has been built in MATLAB. This model in its first version did not apply the contact between wheels and rails. It was necessary to find out, if this simplification is relevant with respect to subsequent simulations within the complex simulation model and its results. Therefore, the contact interaction as a traction force in longitudinal direction in the wheel-rail contact was realized via the Kalker’s linear theory. This article deals with the comparison between models with and without the implementation of the wheel-rail contact and its influence on the damping within the torsion system and retuning of the torsion system

The measurement of the influence of the adhesion loss on the dynamic load of the drive reaction rod on the roller rig

The dynamic behaviour and dynamic phenomena in traction drives of railway vehicle has been studied for decades. Generally, in these days the motivation for this research is to look for answers related with service problems, which has been risen, e.g. an overloading of mechanical components as wheelsets or an intention to improve control systems of traction drives of railway vehicles. This problematic has also motivated the research at the Faculty of Mechanical Engineering at the Czech Technical University (CTU) in Prague. Nowadays it is also usual, that the main research tool has been a simulation based on a mathematical model of a railway vehicle or its specific components, as testing on real vehicles is very demanding regarding costs. However, there is an alternative – a roller rig. At the CTU in Prague there has been modernized the second roller rig for purposes of measurement regarding the torsion dynamics research, to support PhD students for their theses and possibly to extend the education for students oriented on the railway vehicle’s design. This contribution brings results of measurements just from the problematics of torsion oscillations and dynamics. Specifically, further presented measurements are on the loss of the adhesion in the contact of the wheelset and rollers, as the substitution for the railway, its impact on the reaction rod overloading and study of the axle load influence on the transition phenomena

Building an adaptive agent to monitor and repair the electrical power system of an orbital satellite

Over several years we have developed a multistrategy apprenticeship learning methodology for building knowledge-based systems. Recently we have developed and applied our methodology to building intelligent agents. This methodology allows a subject matter expert to build an agent in the same way in which the expert would teach a human apprentice. The expert will give the agent specific examples of problems and solutions, explanations of these solutions, or supervise the agent as it solves new problems. During such interactions, the agent learns general rules and concepts, continuously extending and improving its knowledge base. In this paper we present initial results on applying this methodology to build an intelligent adaptive agent for monitoring and repair of the electrical power system of an orbital satellite, stressing the interaction with the expert during apprenticeship learning

Kinetic Isotope Effects in Multipath VTST: Application to a Hydrogen Abstraction Reaction

In this work we apply multipath canonical variational transition state theory with small-tunneling corrections (MP-CVT/SCT) to the hydrogen abstraction reaction from ethanol by atomic hydrogen in aqueous solution at room temperature. This reaction presents two transition states which can interconvert by internal rotations about single bonds and another two transition states that are non-interconvertible enantiomers to the former structures. The study also includes another three reactions with isotopically substituted species for which there are experimental values of thermal rate constants and kinetic isotope effects (KIEs). The agreement between the MP-CVT/SCT thermal rate constants and the experimental data is good. The KIEs obtained by the MP-CVT/SCT methodology are factorized in terms of individual transition state contributions to facilitate the analysis. It was found that the percentage contribution of each transition state to the total KIE is independent of the isotopic substitutionT.V.A. thanks Fundação de Amparo à Pesquisa do Estado de São Paulo of Brazil for a postdoctoral fellowship. A.D.-D. acknowledges the SONATA-Bis research grant funded by the National Science Centre, Poland (UMO-2014/14/E/ST4/ 00041). A.F.-R. acknowledges partial funding from Ministerio de Economía y Competitividad of Spain (Research Grant No CTQ2014-58617-R) and from Consellería de Cultura, Educación e Ordenación Universitaria of Xunta de Galicia (Research Grant No R2014/051)S