A strategy for lightweight designing of a railway vehicle car body including composite material and dynamic structural optimization

Rolling stock manufacturers are finding structural solutions to reduce power required by the vehicles,and the lightweight design of the car body represents a possible solution.Optimization processes and innovative materials can be combined in order to achieve this goal.In this framework,we propose the redesign and optimization process of the car body roof for a light rail vehicle,introducing a sandwich structure.Bonded joint was used as a fastening system.The project was carried out on a single car of a modern tram platform.This preliminary numerical work was developed in two main steps:redesign of the car body structure and optimization of the innovated system.Objective of the process was the mass reduction of the whole metallic structure,while the constraint condition was imposed on the first frequency of vibration of the system.The effect of introducing a sandwich panel within the roof assembly was evaluated,focusing on the mechanical and dynamic performances of the whole car body.A mass saving of 63%on the optimized components was achieved,corresponding to a 7.6%if compared to the complete car body shell.In addition,a positive increasing of 17.7%on the first frequency of vibration was observed.Encouraging results have been achieved in terms of weight reduction and mechanical behaviour of the innovated car body.

Object-Oriented Modeling of the Variation of Acceleration and Deceleration Characteristics in Relation to Speed Bands for Railway Vehicles

Automated operation and artificial intelligence technology have become essential for ensuring the safety, efficiency, and punctuality of railways, with applications such as ATO (Automatic Train Operation). In this study, the authors propose a method to efficiently simulate the kinematic characteristics of railroad vehicles depending on their speed zone. They utilized the function overloading function supported by a programming language and applied the fourth-order Lunge-Kutta method for dynamic simulation. By constructing an object model, the authors calculated vehicle characteristics and TPS and compared them with actual values, verifying that the developed model represents the real-life vehicle characteristics accurately. The study highlights potential improvements in automated driving and energy consumption optimization in the railway industry.

Application and development in railway vehicles trend of new welding technologies manufacturing industry

This paper introduces the application of new automatic welding technologies in railway vehicles manufacturing industry, and presents the state of art of advanced friction stir welding technology, semi-penetration laser welding technology and laser-arc hybrid welding technology in manufacturing aluminum alloy body shell, stainless steel body shell and bogie. This paper also analyzes the application and development trend of three welding technologies in the future.

A novel anti-slip control approach for railway vehicles with traction based on adhesion estimation with swarm intelligence

Anti-slip control systems are essential for railway vehicle systems with traction.In order to propose an effective anti-slip control system,adhesion information between wheel and rail can be useful.However,direct measurement or observation of adhesion condition for a railway vehicle in operation is quite demanding.Therefore,a proportional–integral controller,which operates simultaneously with a recently proposed swarm intelligencebased adhesion estimation algorithm,is proposed in this study.This approach provides determination of the adhesion optimum on the adhesion-slip curve so that a reference slip value for the controller can be determined according to the adhesion conditions between wheel and rail.To validate the methodology,a tram wheel test stand with an independently rotating wheel,which is a model of some low floor trams produced in Czechia,is considered.Results reveal that this new approach is more effective than a conventional controller without adhesion condition estimation.

RESEARCH AND DEVELOPMENT OF VIRTUAL PROTOTYPE OF RUNNING GEARS FOR RAILWAY VEHICLE

Virtual prototype is an important idea to resolve design problems of railway vehicle. A different development method, which is based on national product and autonomous development, and would like to reflect the specialty of railway vehicle development in China, is presented. According to the developing process of railway vehicle, the research contents and developing method are pointed out. The integration between CAD and performance analysis software on dynamics and strength is mainly considered. In CAD environment, the properties for dynamics computing are extracted directly from the model and exported with model. This method can avoid data losing caused by model rebuilding in CAE software, and increase the direct dependence of product CAD. Then the vehicle model with properties will be used for real-time dynamics and kinematics analysis and simulation. Therefore, the strength of the parts can be analyzed. The results of dynamics and strength analysis will be fed back to optimize the design model. All operations are dispatched by a control platform, and all data are managed according to the principle of PDM. Testing results show this method is correct.

RESEARCH PROGRESS ON STRUCTURAL FATIGUE RELIABILITY DESIGN AND ANALYSIS METHODS OF CHINESE RAILWAY VEHICLES

A state-of-art review is given to the new advances on fatigue reliability design and analysis methods of Chinese railway vehicle＇s structures. First, the structures are subject to a complicated random fatigue stressing history and this history should be determined by combining dynamic simulation and on-line inspection. Second, the random fatigue constitutions belong to an intrinsic fatigue phenomenon and a probabilistic model is developed to well describe them with two measurements of survival probability and confidence, similar model is also presented for the random stress-life rela- tions and extrapolated appropriately into Song fatigue life regime. Third, concept of the fatigue limit should be understood as the fatigue strength at a given fatigue life and a so-called local Basquin model method is proposed for measuring the random strengths. In addition, drawing and application methods of the Goodman-Smith diagram for integrally characterizing the random fatigue strengths are established in terms of ten kilometers. Fourth, a reliability stress-based method is constructed with a consideration of the random constitutive relations. These new advances form a new frame work for railway fatigue reliability design and analysis.

Fusion of Model-Based and Data Driven Based Fault Diagnostic Methods for Railway Vehicle Suspension

Transportation of freight and passengers by train is one of the oldest types of transport, and has now taken root in most of the developing countries especially in Africa. Recently, with the advent and development of high-speed trains, continuous monitoring of the railway vehicle suspension is of significant importance. For this reason, railway vehicles should be monitored continuously to avoid catastrophic events, ensure comfort, safety, and also improved performance while reducing life cycle costs. The suspension system is a very important part of the railway vehicle which supports the car-body and the bogie, isolates the forces generated by the track unevenness at the wheels and also controls the attitude of the car-body with respect to the track surface for ride comfort. Its reliability is directly related to the vehicle safety. The railway vehicle suspension often develops faults;worn springs and dampers in the primary and secondary suspension. To avoid a complete system failure, early detection of fault in the suspension of trains is of high importance. The main contribution of the research work is the prediction of faulty regimes of a railway vehicle suspension based on a hybrid model. The hybrid model framework is in four folds;first, modeling of vehicle suspension system to generate vertical acceleration of the railway vehicle, parameter estimation or identification was performed to obtain the nominal parameter values of the vehicle suspension system based on the measured data in the second fold, furthermore, a supervised machine learning model was built to predict faulty and healthy state of the suspension system components (damage scenarios) based on support vector machine (SVM) and lastly, the development of a new SVM model with the damage scenarios to predict faults on the test data. The level of degradation at which the spring and damper becomes faulty for both primary and secondary suspension system was determined. The spring and damper becomes faulty when the nominal values degrade by 50% and 40% and 30% and 40% for the secondary and primary suspension system respectively. The proposed model was able to predict faulty components with an accuracy of 0.844 for the primary and secondary suspension system.

Stochastic dynamic simulation of railway vehicles collision using data-driven modelling approach

Using stochastic dynamic simulation for railway vehicle collision still faces many challenges,such as high modelling complexity and time-consuming.To address the challenges,we introduce a novel data-driven stochastic process modelling(DSPM)approach into dynamic simulation of the railway vehicle collision.This DSPM approach consists of two steps:(i)process description,four kinds of kernels are used to describe the uncertainty inherent in collision processes;(ii)solving,stochastic variational inferences and mini-batch algorithms can then be used to accelerate computations of stochastic processes.By applying DSPM,Gaussian process regression(GPR)and finite element(FE)methods to two collision scenarios(i.e.lead car colliding with a rigid wall,and the lead car colliding with another lead car),we are able to achieve a comprehensive analysis.The comparison between the DSPM approach and the FE method revealed that the DSPM approach is capable of calculating the corresponding confidence interval,simultaneously improving the overall computational efficiency.Comparing the DSPM approach with the GPR method indicates that the DSPM approach has the ability to accurately describe the dynamic response under unknown conditions.Overall,this research demonstrates the feasibility and usability of the proposed DSPM approach for stochastic dynamics simulation of the railway vehicle collision.

A Brief Introduction to Changchun Railway Vehicle Co.,Ltd.

Changchun Railway Vehicle Co.,Ltd.(CRC) was founded in March 2002.Initiated by China's North Locomotive & Rolling Stock Industry (group) Corporation,and based on the main business as well as the capital of the former Changchun Car Company,CRC was founded as new joint-stock company,

Analysis of Fresh Air Volume of Air-conditioning System for Railway Vehicles

The relevant standard requirements both in domestic and abroad provide the basis for designing air-conditioning system of railway vehicles present. However, there are great differences in the fresh air volume indicators among different standards requirements, and the requirements of each vehicle procurement contracts are also different. The design of air-conditioning become difficult above these. In this paper, the fresh air volume of different type railway vehicles is analyzed from health and equipment electricity consumption according to the railway vehicles air-conditioning system standard requirements in domestic and abroad. Some advises for designing air-conditioning system of railway vehicles through the fresh air volume calculation and comparison for domestic air-conditioning system of railway vehicles was provided.

Comprehensive modeling strategy for thermomechanical tribological behavior analysis of railway vehicle disc brake system

A comprehensive modeling strategy for studying the thermomechanical tribological behaviors is proposed in this work.The wear degradation considering the influence of temperature(T)is predicted by Archard wear model with the help of the UMESHMOTION subroutine and arbitrary Lagrangian–Eulerian(ALE)remeshing technique.Adopting the proposed method,the thermomechanical tribological behaviors of railway vehicle disc brake system composed of forged steel brake disc and Cu-based powder metallurgy(PM)friction block are studied systematically.The effectiveness of the proposed methodology is validated by experimental test on a self-designed scaled brake test bench from the perspectives of interface temperature,wear degradation,friction noise and vibration,and contact status evolution.This work can provide an effective way for the investigation of thermomechanical tribological behaviors in the engineering field.

Impact vibration behavior of railway vehicles:a state-of-the-art overview

Excessive vibrations of railway vehicles induced by dynamic impact loadings have a significant impact on train operating safety and stability;however,due to the complexity and diversity of railway lines and service environment,they are extremely difficult to eliminate.A comprehensive overview of recent studies on the impact vibration behavior of railway vehicles was given in this paper.First,the sources of impact excitations were categorized in terms of wheel-rail contact irregularity,aerodynamic loads,and longitudinal impulses by train traction/braking.Then the main research approaches of vehicle impact vibration were briefly introduced in theoretical,experimental,and simulation aspects.Also,the impact vibration response characteristics of railway vehicles were categorized and examined in detail to various impact excitation sources.Finally,some attempts of using the railway vehicle vibration to detect track defects and the possible mitigation measures were outlined.

Evaluation of power regeneration in primary suspension for a railway vehicle

To improve the fuel economy of rail vehicles,this study presents the feasibility of using power regenerating dampers(PRDs)in the primary suspension systems of railway vehicles and evaluates the potential and recoverable power that can be obtained.PRDs are configured as hydraulic electromagnetic-based railway primary vertical dampers and evaluated in parallel and series modes(with and without a viscous damper).Hydraulic configuration converts the linear behavior of the track into a unidirectional rotation of the generator,and the electromagnetic configuration provides a controllable damping force to the primary suspension system.In several case studies,generic railway vehicle primary suspension systems that are configured to include a PRD in the two configuration modes are modeled using computer simulations.The simulations are performed on measured tracks with typical irregularities for a generic UK passenger route.The performance of the modified vehicle is evaluated with respect to key performance indicators,including regenerated power,ride comfort,and running safety.Results indicate that PRDs can simultaneously replace conventional primary vertical dampers,regenerate power,and exhibit desirable dynamic performance.A peak power efficiency of 79.87%is theoretically obtained in series mode on a top-quality German Intercity Express track(Track 270)at a vehicle speed of 160 mile/h(~257 km/h).

Modeling and simulation of railway vehicle vertical dynamic behavior by considering the effect of passenger-carbody coupling vibration

In order to reflect the vertical random vibration characteristics of railway vehicles more truly and effectively,this paper regards the human body as a single-degree-of-freedom system attached to the bottom of the carriage,and establishes a vertical dynamic model of railway vehicles by considering the influence of the coupling vibration effect between the passenger and the car body.The correctness of the model is verified by the real vehicle test.Then,the influence of the passengers on the vertical vibration characteristics of railway vehicles is analyzed,and the influence of the railway vehicle vibration on the vertical vibration characteristics of passengers is discussed in this paper.The research made in this paper can provide an effective model reference for the analysis of the vertical random vibration characteristics of railway vehicles and passengers,and for the optimization design of the suspension system parameters.

NONLINEAR OSCILLATIONS AND CHAOS IN A RAILWAY VEHICLE SYSTEM

The study of nonlinear oscillations and chaos of a railway freight car is undertaken. The vehicle is considered as a multiple rigid body system with 9 degrees of freedom. The vehicle forward speed is taken as the control parameter of the system. Hopf bifurcation point, limit cycles, quasiperiodic and chaotic motions of the system are computed by use of numerical methods. The identification of periodic, quasiperiodic and chaotic motions of the system is carried out by using the methods of phase plane portrait and Poincare map. Numerical results show that chaotic motion appears via the route of quasiperiodicity when the vehicle runs over a certain speed.

Study on dynamic optimization of the double railway suspended vehicle for automatic transportation in the welding shop

The 2DOF dynamic equations of the doable railway suspended vehicle for automatic transportation in the welding shop are established. The sensitivities are analyzed. The parameter design is researched in ADAMS in terms of the inner railway radius, wheelbase, gauge, girder length of the doable railway suspended vehicle for automatic transportation in the welding product line. The mutual-restriction among the design variables is discussed and the selective ranges of the variables are confirmed. The result shows that the stability of the doable railway suspended vehicle for automatic transportation in the welding product line depends on parameters of the inner railway radius, wheelbase, gauge, girder length. The optimal results of the optimal objective and design variables have research significance for the virtual prototype of the doable suspension railway automation vehicle. The optimal results are input into the simulation model iteratively and the simulation results are fed back to the physical prototype. The veracity and reliability of peoformance forecast are improved so that the manufacture cost of the doable suspension railway automation vehicle is reduced significantly.

Theoretical and Experimental Study of Hopf Bifurcation and Limit Cycles of Railway Vehicle Hunting

The nonlinear hunting stability of railway vehicles is studied theoretically and experimentally in this paper.The Hopf bifurcation point is determined through calculating the eigenvalues of the system linearization equations incorporating with the golden cut method.The bifurcated limit cycles are computed by use of the shooting method to solve the boundary value problem of the system differential equations.Experimental validation to the numerical results is carricd out by utilizing the full scale roller test rig.

Polygonisation of railway wheels:a critical review

Polygonisation is a common nonuniform wear phenomenon occurring in railway vehicle wheels and has a severe impact on the vehicle–track system,ride comfort,and lineside residents.This paper first summarizes periodic defects of the wheels,including wheel polygonisation and wheel corrugation,occurring in railways worldwide.Thereafter,the effects of wheel polygonisation on the wheel–rail interaction,noise and vibration,and fatigue failure of the vehicle and track components are reviewed.Based on the different causes,the formation mechanisms of periodic wheel defects are classified into three categories:(1)initial defects of wheels,(2)natural vibration of the vehicle–track system,and(3)thermoelastic instability.In addition,the simulation methods of wheel polygonisation evolution and countermeasures to mitigate wheel polygonisation are presented.Emphasis is given to the characteristics,effects,causes,and solutions of wheel polygonisation in metro vehicles,locomotives,and highspeed trains in China.Finally,the guidance is provided on further understanding the formation mechanisms,monitoring technology,and maintenance criterion of wheel polygonisation.

ExperimentalVerificationofaDetailedVehicle┐TrackVerticalInteractionModel

A theoretical model has been developed to investigate vertical dynamic interactions between railway vehicles and tracks. Wheel rail forces and dynamic responses of vehicle and track components can be simulated with the model. The model has been applied to the study of high speed and heavy haul railway dynamic problems. In order to verify the model completely, a full scale field experiment was performed on the Chinese Datong Qinhuangdao railway. Accelerations of rail, sleeper and ballast were measured and compared with the simulated results both in time domain and in frequency domain.

Effect of wheelset flexibility on wheel–rail contact behavior and a specific coupling of wheel–rail contact to flexible wheelset

The fexibility of a train＇s wheelset can have a large effect on vehicle–track dynamic responses in the medium to high frequency range.To investigate the effects of wheelset bending and axial deformation of the wheel web,a specifi coupling of wheel–rail contact with a fexible wheelset is presented and integrated into a conventional vehicle–track dynamic system model.Both conventional and the proposed dynamic system models are used to carry out numerical analyses on the effects of wheelset bending and axial deformation of the wheel web on wheel–rail rolling contact behaviors.Excitations with various irregularities and speeds were considered.The irregularities included measured track irregularity and harmonic irregularities with two different wavelengths.The speeds ranged from 200 to400km/h.The results show that the proposed model can characterize the effects of fexible wheelset deformation on the wheel–rail rolling contact behavior very well.