一系悬挂对重载货车运行影响研究

传统三大件转向架没有一系悬挂,货车运行中,短波轨道不平顺作用下轮轨中低频响应对于货车的影响较为明显。部分重载货车采用橡胶垫作为一系悬挂,降低运行时轮轨相互作用对于货车动力学性能的影响。本文以一种澳大利亚铁路重载货物运输中大量采用的30t轴重三大件转向架货车作为研究对象,参考澳大利亚铁路行业安全标准,采用多体动力学仿真分析方法,建立货车完整动力学模型,比较分析四种一系悬挂下,货车在不同线路、不同速度、不同轮轨接触条件下的磨耗指数、脱轨系数与P2力,据此分析橡胶垫垂向刚度对于货车动力学性能的影响。研究结果表明:一系橡胶垫可以有效降低干燥轮轨接触状态下货车车轮的磨耗指数与P2力,但会造成轮轨润滑状态下货车车轮的磨耗指数与P2力的增大,一系橡胶垫对于货车脱轨系数影响并不明显。

Longitudinal dynamics and energy analysis for heavy haul trains

Whole trip longitudinal dynamics and energy analysis of heavy haul trains are required by operators and manufacturers to enable optimisation of train controls and rolling stock components. A new technology named train dynamics and energy analyser/train simulator （TDEAS） has been developed by the State Key Laboratory of Traction Power in China to perform detailed whole trip longitudinal train dynamics and energy analyses. Facilitated by a controller user interface and a graphic user interface, the TDEAS can also be used as a train driving simulator. This paper elaborates the modelling of three primary parts in the TDEAS, namely wagon connection systems, air brake systems and train energy components. TDEAS uses advanced wedge-spring draft gear models that can simulate a wider spectrum of friction draft gear behaviour. An effective and efficient air brake model that can simulate air brake systems in various train configurations has been integrated. In addition, TDEAS simulates the train energy on the basis of a detailed longitudinal train dynamics simulation, which enables a further perspective of the train energy composition and the overall energy consumption. To demonstrate the validity of the TDEAS, a case study was carried out on a 120-km-long Chinese railway. The results show that the employment of electric locomotives with regenerative braking could bring considerable energy benefits. Nearly 40 % of the locomotive energy usage could be collected from the dynamic brake system. Most of tractive energy was dissipated by propulsion resistance that accounted for 42.48 % of the total energy. Only a small amount of tractive energy was dissipated by curving resistance, air brake and draft gear systems.

A review of hydrogen technologies and engineering solutions for railway vehicle design and operations

Interest in hydrogen-powered rail vehicles has gradually increased worldwide over recent decades due to the global pressure on reduction in greenhouse gas emissions,technology availability,and multiple options of power supply.In the past,research and development have been primarily focusing on light rail and regional trains,but the interest in hydrogen-powered freight and heavy haul trains is also growing.The review shows that some technical feasibility has been demonstrated from the research and experiments on proof-of-concept designs.Several rail vehicles powered by hydrogen either are currently operating or are the subject of experimental programmes.The paper identifies that fuel cell technology is well developed and has obvious application in providing electrical traction power,while hydrogen combustion in traditional IC engines and gas turbines is not yet well developed.The need for on-board energy storage is discussed along with the benefits of energy management and control systems.

Analysis of positioning of wayside charging stations for hybrid locomotive consists in heavy haul train operations

Hybrid locomotive concepts have been considered as a step towards converting the railway industry into a green transport mode.One of the challenges in integrating a hybrid locomotive in the train consist is that the battery pack in the locomotive needs to be recharged during a long-haul trip which requires stopping of the train.A typical battery pack requires about 1 h to recharge which is unacceptable.With the improvement in the charging system,it is now possible that the same capacity battery pack could be recharged in 10–12 min which can be a competitive option for the railway companies.This paper proposes a method based on simulation to evaluate the positioning of charging stations on a train network.A typical example of a heavy haul train operation hauled by diesel-electric and hybrid locomotives is used to demonstrate the method by using simulation softwares.The result of the simulation study show that the method developed in this paper can be used to evaluate the state of charge(SoC)status of a hybrid locomotive along the track.It is also shown that the SoC status obtained by the simulation method can be further used to assess the positions of charging stations along the track at the design stage.

Train energy simulation with locomotive adhesion model

Railway train energy simulation is an important and popular research topic.Locomotive traction force simulations are a fundamental part of such research.Conventional energy calculation models are not able to consider locomotive wheel-rail adhesions,traction adhesion control,and locomotive dynamics.This paper has developed two models to fill this research gap.The first model uses a 2D locomotive model with 27 degrees of freedom and a simplified wheel-rail contact model.The second model uses a 3D locomotive model with 54 degrees of freedom and a fully detailed wheel-rail contact model.Both models were integrated into a longitudinal train dynamics model with the consideration of locomotive adhesion control.Energy consumption simulations using a conventional model(1D model)and the two new models(2D and 3D models)were conducted and compared.The results show that,due to the consideration of wheel-rail adhesion model and traction control in the 3D model,it reports less energy consumption than the 1D model.The maximum difference in energy consumption rate between the 3D model and the 1D model was 12.5%.Due to the consideration of multiple wheel-rail contact points in the 3D model,it reports higher energy consumption than the 2D model.An 8.6%maximum difference in energy consumption rate between the 3D model and the 1D model was reported during curve negotiation.

昆士兰和COALlink重载煤炭运输列车动力学仿真的比较

对南非Spoornet和澳大利亚昆士兰铁路两大煤炭运输系统的重载运输列车进行了比较,这两大系统根据各自不同的运输需要设计了不同形式的列车,结合仿真和现场测试的数据,对产生这些不同的原因进行了探索。对由2个相同单元连挂起来组成的COALlink动力分散列车的优点进行了详细研究。本文还对两大系统的列车进行了增加总重的仿真研究。为了获得归一化的比较方法,每次仿真都采用相同的牵引方式,这一技术突出了两大系统的相似之处和不同之处,仿真结果证实了昆士兰铁路的列车需要增大功率-质量比,同时表明了动力分散对降低列车作用力是有益处的。

Problems,assumptions and solutions in locomotive design,traction and operational studies

Locomotive design is a highly complex task that requires the use of systems engineering that depends upon knowledge from a range of disciplines and is strongly oriented on how to design and manage complex systems that operate under a wide range of different train operational conditions on various types of tracks.Considering that field investigation programs for locomotive operational scenarios involve high costs and cause disruption of train operations on real railway networks and given recent developments in the rollingstock compliance standards in Australia and overseas that allow the assessment of some aspects of rail vehicle behaviour through computer simulations,a great number of multidisciplinary research studies have been performed and these can contribute to further improvement of a locomotive design technique by increasing the amount of computer-based studies.This paper was focused on the presentation of the all-important key components required for locomotive studies,starting from developing a realistic locomotive design model,its validation and further applications for train studies.The integration of all engineering disciplines is achieved by means of advanced simulation approaches that can incorporate existing AC and DC locomotive designs,hybrid locomotive designs,full locomotive traction system models,rail friction processes,the application of simplified and exact wheel-rail contact theories,wheel-rail wear and rolling contact fatigue,train dynamic behaviour and intrain forces,comprehensive track infrastructure details,and the use of co-simulation and parallel computing.The cosimulation and parallel computing approaches that have been implemented on Central Queensland University’s High-Performance Computing cluster for locomotive studies will be presented.The confidence in these approaches is based on specific validation procedures that include a locomotive model acceptance procedure and field test data.The problems and limitations presented in locomotive traction studies in the way they are conducted at the present time are summarised and discussed.

Rail temperature variation under heavy haul operations

There currently does not exist in industry a reliable method for the detection of rail foot flaws.Like their head-based counterparts,foot flaws result in broken rail with potentially catastrophic consequences.A proposed area of research for the detection of these flaws is thermography,a non-contact method of measuring and analysing infrared emissions from an object under test.In industry,active excitation thermography is the most common,requiring an excitation source.This paper will present a temperature measurement system and a method of transient temperature extraction from the running rails for the effects of a passing train to evaluate heat transfer in the practical rail environment.The outcomes of these results will provide future direction in the development of a rail heat transfer model and determine if train passage provides enough active excitation for a thermography-based detection technique.

A review on design and testing methodologies of modern freight train draft gear system

Rolling stock connection systems are key to running longer and heavier trains as they provide both the connections of vehicles and the damping,providing the longitudinal suspension of the train.This paper focuses on the evolution of both connection and stiffness damping systems.Focus is on freight rolling stock,but passenger draw gears are also examined.It was found that connection systems have evolved from the buff and chain system used in the pioneer railways of the 1800s to the modern auto-coupler connection systems that are in-service worldwide today.Refined versions of the buff and chain coupling are,however,still in use in the EU,UK,South America and India.A wide range of auto-coupler systems are currently utilised,but the AAR coupler(Janney coupler)remains the most popular.A further variation that persists is the SA3 coupler(improved Wilson coupler)which is an alternative auto-coupler design used mainly throughout the former Soviet Union.Restricting the review to auto-coupler systems allowed the paper to focus on draft gears which revealed polymer,polymer-friction,steel spring-friction,hydraulic draft gears and sliding sill cushioning systems.Along with the single compressive draft gear units balanced and floating plate configurations are also presented.Typical draft gear acceptance standards are presented along with modelling that was included to aid in presentation of the functional characteristics of draft gears.

Preface to special issue on hybrid and hydrogen technologies for railway operations

These are exciting times for those working to develop and introduce zero emission technologies for the manufacture and operation of clean transport systems.The automotive industry in particular is taking rapid and significant steps to develop and implement clean and sustainable transport technologies.The railway industry is,relatively speaking,conservative in its progress in this field because it requires expensive long-term financial investment in rolling stock and railway infrastructure.However,the rail industry is also beginning to increase the pace of development.

Feasibility in assessing the dipped rail joint defects through dynamic response of heavy haul locomotive

The feasibility of monitoring the dipped rail joint defects has been theoretically investigated by simulating a locomotive-mounted acceleration system negoti- ating several types of dipped rail defects. Initially, a comprehensive locomotive-track model was developed using the multi-body dynamics approach. In this model, the locomotive car-body, bogie frames, wheelsets and driving motors are considered as rigid bodies; track modelling was also taken into account. A quantitative relationship between the characteristics （peak-peak values） of the axle box accelerations and the rail defects was determined through simulations. Therefore, the proposed approach, which combines defect analysis and comparisons with theoretical results, will enhance the ability for long-term monitoring and assessment of track systems and provides more informed preventative track maintenance strategies.

Recent advances in wheel–rail RCF and wear testing

The wear and rolling contact fatigue (RCF) testing approaches for wheels and rails have been reviewedand evaluated in this study. The study points out the advantages and limitations of the existing approaches. Thebroad analysis revealed that scaled laboratory-based wear testing is widely applied. However, it is necessary topredetermine the input parameters and observing parameters for scaled wear testing for three reasons: first, toemulate the real-world scenarios as closely as possible;second, to postprocess the results received from the scaledtesting and transfer them into real practice at full scale;third, to present the results in a legible/appropriate format.Therefore, most of the important parameters required for wear testing have been discussed with fundamental andsystematic explanations provided. Additionally, the transition of the parameters from the real-world into the testdomain is explained. This study also elaborates on the challenges of the RCF and wear testing processes andconcludes by providing major considerations toward successful testing.

Coupler force and fatigue assessments with stochasticdraft gear frictions

Train dynamics and component fatigue assessments are important steps towards successful operations of long heavy haul trains.Longitudinal train dynamics(LTD)simulation is an effective and efficient approach in this regard.Draft gear friction has been known to have a strong stochastic feature.However,relevant train dynamics simulations have not been reported in open literature.This paper uses experimental data to extract the stochastic feature of draft gear friction.The stochastic feature is then introduced into LTD simulations.Coupler force and fatigue damage assessments were conducted by simulating a heavy haul train that has 244 vehicles and weighs nearly 30,000 tonnes.The results show that average in-train force variations due to stochastic friction were 55 and 40 kN for the traction and air brake cases respectively;maximum force variations were 207 and 98 kN for the traction and air brake cases respectively.Coupler fatigue calculations are even more sensitive to stochastic draft gear friction;the largest variations can be up to 700 times different due to the strong nonlinearity of fatigue calculation procedures.Stochastic friction is an unavoidable nature in friction draft gears.Simulations using stochastic draft gear friction can deliver results that are more robust and reliable.