Fundamentals of vehicle–track coupled dynamics

This paper presents a framework to investigate the dynamics of overall vehicle–track systems with emphasis on theoretical modelling, numerical simulation and experimental validation. A three-dimensional vehicle–track coupled dynamics model is developed in which a typical railway passenger vehicle is modelled as a 35-degree-of-freedom multi-body system. A traditional ballasted track is modelled as two parallel continuous beams supported by a discrete-elastic foundation of three layers with sleepers and ballasts included. The non-ballasted slab track is modelled as two parallel continuous beams supported by a series of elastic rectangle plates on a viscoelastic foundation. The vehicle subsystem and the track subsystem are coupled through a wheel–rail spatial coupling model that considers rail vibrations in vertical, lateral and torsional directions. Random track irregularities expressed by track spectra are considered as system excitations by means of a time–frequency transformation technique. A fast explicit integration method is applied to solve the large nonlinear equations of motion of the system in the time domain. A computer program named TTISIM is developed to predict the vertical and lateral dynamic responses of the vehicle–track coupled system. The theoretical model is validated by full-scale field experiments, including the speed-up test on the Beijing–Qinhuangdao line and the high-speed running test on the Qinhuangdao–Shenyang line. Differences in the dynamic responses analysed by the vehicle–track coupled dynamics and by the classical vehicle dynamics are ascertained in the case of vehicles passing through curved tracks.     

Integration of car-body flexibility into train–track coupling system dynamics analysis

The resonance vibration of flexible car-bodies greatly affects the dynamics performances of high-speed trains. In this paper, we report a three-dimensional train–track model to capture the flexible vibration features of high-speed train carriages based on the flexible multi-body dynamics approach. The flexible car-body is modelled using both the finite element method (FEM) and the multi-body dynamics (MBD) approach, in which the rigid motions are obtained by using the MBD theory and the structure deformation is calculated by the FEM and the modal superposition method. The proposed model is applied to investigate the influence of the flexible vibration of car-bodies on the dynamics performances of train–track systems. The dynamics performances of a high-speed train running on a slab track, including the car-body vibration behaviour, the ride comfort, and the running safety, calculated by the numerical models with rigid and flexible car-bodies are compared in detail. The results show that the car-body flexibility not only significantly affects the vibration behaviour and ride comfort of rail carriages, but also can has an important influence on the running safety of trains. The rigid car-body model underestimates the vibration level and ride comfort of rail vehicles, and ignoring carriage torsional flexibility in the curving safety evaluation of trains is conservative.     

Extended applications of track irregularity probabilistic model and vehicle–slab track coupled model on dynamics of railway systems

Track irregularities are inevitably in a process of stochastic evolution due to the uncertainty and continuity of wheel–rail interactions. For depicting the dynamic behaviours of vehicle–track coupling system caused by track random irregularities thoroughly, it is a necessity to develop a track irregularity probabilistic model to simulate rail surface irregularities with ergodic properties on amplitudes, wavelengths and probabilities, and to build a three-dimensional vehicle–track coupled model by properly considering the wheel–rail nonlinear contact mechanisms. In the present study, the vehicle–track coupled model is programmed by combining finite element method with wheel–rail coupling model firstly. Then, in light of the capability of power spectral density (PSD) in characterising amplitudes and wavelengths of stationary random signals, a track irregularity probabilistic model is presented to reveal and simulate the whole characteristics of track irregularity PSD. Finally, extended applications from three aspects, that is, extreme analysis, reliability analysis and response relationships between dynamic indices, are conducted to the evaluation and application of the proposed models.     

A locomotive–track coupled vertical dynamics model with gear transmissions

A gear transmission system is a key element in a locomotive for the transmission of traction or braking forces between the motor and the wheel–rail interface. Its dynamic performance has a direct effect on the operational reliability of the locomotive and its components. This paper proposes a comprehensive locomotive–track coupled vertical dynamics model, in which the locomotive is driven by axle-hung motors. In this coupled dynamics model, the dynamic interactions between the gear transmission system and the other components, e.g. motor and wheelset, are considered based on the detailed analysis of its structural properties and working mechanism. Thus, the mechanical transmission system for power delivery from the motor to the wheelset via gear transmission is coupled with a traditional locomotive–track dynamics system via the wheel–rail contact interface and the gear mesh interface. This developed dynamics model enables investigations of the dynamic performance of the entire dynamics system under the excitations from the wheel–rail contact interface and/or the gear mesh interface. Dynamic interactions are demonstrated by numerical simulations using this dynamics model. The results indicate that both of the excitations from the wheel–rail contact interface and the gear mesh interface have a significant effect on the dynamic responses of the components in this coupled dynamics system.     

Survey of the development of Chinese heavy trucks

Heavy trucks are tending to get bigger. The market share for those with a payload of more than 10 tons is increasing rapidly while that for below 10 tons is contracting. The scramble for markets of the most-favored vehicle types is keenest among......     

Highlights of Selected Auto Groups of China in 1999

According to the information coming from concerned depart-ment, the total production of auto would be 1.67 million units in 1999, including 530,000 cars. You can read programs set by selected auto groups below for details: FAW Group ◆Production and sales: 300 thousand units. ◆Products: widen the range     

Characteristics of Methods on the Circulation of Used Vehicles

On Aug 29 2005, the Ministry of Commerce, together with other relevant government departments, issued the Methods and the new went into effect on Oct. The used vehicle market is regarded a potential section which can incentive consumption and increase tax income as well. But the market can hardly meet the requirement of the society. The critical reason behind this is the lack of related rules. The new policy is designed to meet the demand of post-WTO conditions. The 5 chapter, 37 article M…     

Important characteristics of the new round of economic growth

LIU Shijin, the director of the Industry and Economy Department of the State Council Development and Research Center, made an analysis on the import characteristics of the new round of economic growth in his recent article. In his opinion, automobile and housing have become two of the leading industries for the new round of economic growth, which have moved into a period of mass consumption. In addition, he thought, the new round of economic growth is also related to the colossal market capacity, the gathering effect of industries and the emergence of city groups. There is no less of incisive views in his article. Our editor would select some of them to share with the readers based on the auto industry's real situation.     

Profile of TARI

Founded in May 1978, Tianjin Automobile Research Institute (TARI), directly under Tianjin Automobile Industry (Group) Corporation Ltd., is a research and development center for Tianjin' s automobile industry. TARI covers a land area of 45 000 square meters with building area of 13051 square meters and an under-construction area of 5060 square meters. The institute has a staff of 370     

Excavators of Shanghai

豆瓣用户"席子"在他的相册《Shanghai Excavator》中感叹道:"这是一个挖掘机的黄金时代。"别人眼中的残垣、废砖、钢筋、烟尘,都成了他独特构图的一部分。五年来,他用镜头记录了上海的拆与建,用光影描绘了新旧交替的景象。他的模特,名字叫作挖掘机。     

The Probe of Significance of Text Analysis in Translation

Part I IntroductionTranslating is an activity which full of hardship.And the very be-ginning of this hardship is text analysis.Whenever a translator goes abouta text,the first step he takes is always to analyze it.This step is to trans-lation what the fir…     

Profile of CARI

Established in 1957 and located in Changchun, Changchun Automobile Research Institute (CARI) one of the important R & D organizations in China is mainly responsible for the R&D of auto products of FAW group.     

Index of 2002

刀tI6(Issue.一Pages) 2002 WIShN...(1es...............................................................................................................................................................……(1一1)~12).n加份抽姗 AninterviewwithZHANGxingye..........................................……,.…‘.........……,……,..................................................……(,一9) AninterviewwithzHANGxiaoyu.............................................................……,....................…     

An Interview with ZHANG Xingye—— Honorary President of Society of Automotive Engineers of China

Reporter: Please say something about the entire structure of Chinese auto industry after the WTO entry, and what do you think it should do to cope with the new challenges? Zhang: This is an old question we have talked about for years. Now China is already an official member of the WTO and what we discussed before should become specific policies or measures.