Railway Vehicle Body Research Articles

Research on Lightweight Rail Vehicle Body Based on Sensitivity Analysis

In view of the development trend of rail vehicles towards higher operating speed and low power consumption, a scheme for a lightweight rail vehicle body is proposed, based on sensitivity analysis. Using topology optimization of the vehicle body section structure, finite element models of the vehicle body section structure under single working conditions and multiple working conditions were established, respectively, and the force transmission path of the vehicle body structure under different working conditions was obtained under different working conditions. The topology of the cross-sectional structure of the vehicle body was optimized by the compromise planning method with weights. Then, a reconstruction and performance analysis of the car body section was carried out based on the optimization results and finally the finite difference method was used to analyze the sensitivity of the vehicle body structure and the vehicle body size was optimized based on the sensitivity analysis results. The results showed that the weight reduction rate of the railway vehicle body section stiffened plate was 4.47% compared to the optimization period and the modal performance analysis results of the optimized structure met the requirements. The weight reduction ratio of the optimized body structure was 21.6%

Vertical bending vibration analysis of the car body of railway vehicle

The paper features the analysis of the symmetrical vertical bending of the car body railway vehicle, when vehicle is running along on a track with vertical irregularities described in the form of the power spectral density (PSD). The analysis relies on the numerical simulations results, developed based on a rigid-flexible coupled vehicle model, with seven-degree freedom, where the car body is modelled as an Euler-Bernoulli type equivalent beam. The vibration behaviour of the car body is evaluated based on the PSD of the car body acceleration (PSD acceleration), calculated at the car body centre and above the bogies. The main characteristics of the car body bending vibration are pointed in correlation with velocity, the secondary suspension damping and the car body elasticity characteristics.

Wheel flat detectability for Y25 railway freight wagon using vehicle component acceleration signals

A wheel flat is a common fault in railway vehicles that may develop after incorrect brake application, or localised wheel-rail adhesion reduction. Operators detect wheel flats using wayside systems that are not capable of delivering real-time alarms. A wheel flat defect was modelled and introduced to a railway wagon multibody dynamic simulation to study the vehicle dynamic behaviour triggered by such wheel tread defect. Bogie-based and car body-based wheel flat detection was evaluated to determine eventual hardware robustness and signal processing requirements for on-board wheel flat detection devices. Various vehicle operating conditionds and wheel flat defects were simulated to analyse the wheel flat impact propagation throughout the railway vehicle bodies. Wheel defect detectability was assessed using detectability indicators (DIs) based on envelope power spectrum analysis, crest factor and RMS. It was found that bogie and car body-based wheel flat detectability is highly dependent on the track characteristics. The wheel flat signature was reduced in the wheelset-bogie and bogie-car body interfaces, indicating that advanced signal processing techniques are required for bogie-based and car body-based wheel flat detection systems. The DIs showed clear differences between healthy and faulty wheelset and bogie frame acceleration signals, which is promising for eventual on-board wheel flat detection systems.

Analysis of the Sound Field Changes in Railway Tunnel by Incorporating Porous Aggregate Sound Absorbing Materials

While travelling through railways, passengers are often subjected to a train’s interior noise. Compared to an open area, such noise increases when a train passes through a tunnel because the interior of the tunnel generally comprises a concrete surface with a very low rate of sound absorption, and the noise from railway vehicles undergoes multiple reflections inside the tunnel. To reduce a train’s interior noise while passing through a tunnel, it is necessary to analytically and experimentally study the noise reduction effect caused by incorporating high strength porous aggregate sound absorbing materials that satisfy the material performance standards required by railway facilities. Acoustic simulation of the sound field within a tunnel has been previously analyzed for predicting the noise reduction caused by porous aggregate sound absorbing materials, before and after installation. Furthermore, the sound absorption performance in the space between the installation section and the non-installation section has been compared by measuring the reverberation time after incorporating sound absorbing materials in an actual test tunnel. In this study, a method for efficient arrangement of sound absorbing materials is proposed based on the sound field analysis results of railway tunnels. The proposed study can thus provide fundamental data for further research on aspects such as sound insulation design for railway vehicle body and railway infrastructure. Key words: Railway Tunnel, Train Interior Noise, Sound Absorbing Material, Acoustic Analysis, Reverberation Time

Study on quantitative ultrasonic test for Nd:YAG laser welding of thin stainless steel sheet

In this paper, laser welding for the stainless steel lap joint used in the railway vehicle body has been studied based on the analysis of the ultrasonic test. The weld width is evaluated by the analysis of ultrasonic testing signals during the ultrasonic scanning process. The changes of the echo and main frequency are in good agreement with the positions of the probe. The semi-attenuation method and frequency domain analysis are established based on the A-scan signals and frequency spectrum characteristic curves. From the analysis of the error statistics, the frequency domain analysis has a higher accuracy and stability, which can meet the requirements of engineering applications. The equivalent weld width is defined based on the C-scan imaging and the quantitative ultrasonic test is achieved. The tensile shear measurements of welds show that the equivalent weld widths have the same change rules with the values of the tensile shear strength and provide an important basis for the quality evaluation of the laser welding.

Identification of Aluminum Alloy Flow Stress to Determine FEM Analysis Constitutive Equation for Machining Material

To predict accurate cutting forces and residual stresses while machining products or to design optimum machining conditions like friction stir welding (FSW), FEM analyses are effective because they can reduce the cost of product design and improve product qualities. In order to conduct these FEM analyses precisely, it is necessary to determine accurate flow stresses of workpieces used for the constitutive equations of analyses that generally have a wide range of temperatures and strain rates. Correct identification of flow stress can lead to better analysis results close to actual phenomenon. In this study, focusing on 6061-T6 aluminum alloy used for objects such as civil engineering structures and railway vehicle bodies, we investigated the properties for machining the material. For this, we carried out an inverse analysis to understand the flow stress of 6061-T6 machined at high-strain rates and high temperatures. Then, we used this identified flow stress in the constitutive equation of FEM models, and inspected the accuracy of material properties conducting verification experiments and analyses to check the cutting forces and chip temperature while machining. As a result, we obtained good correlations between verification experiments and an analysis, which means the identified flow stress can be used for precise FEM analyses when machining materials.

Proposal of a new method for strength evaluating of construction of railway vehicles

This article presents two methods for evaluating the strength of the hood of railway locomotives. The hood is subject to the European standards for railway applications EN 12663-1 Railway applications Structural requirements of railway vehicle bodies Part 1: Locomotives and passenger rolling stock. Czech Standards Institute (2010). The first method is based on the European standard for railway applications EN 12663-1 Railway applications Structural requirements of railway vehicle bodies Part 1: Locomotives and passenger rolling stock. Czech Standards Institute (2010). This method is based on the principle of evaluation of the pseudo-elastic stress. The second method uses the results of geometrically and materially nonlinear numerical analyses. The second method is based on the knowledge of modern science and technology. Structural strength is then evaluated from the real limit state. Using both methods for strength evaluating is shown in this paper (strength evaluation of hood of diesel electric locomotive). The original construction of the hood is analyzed in the first part of this paper. Structural changes are proposed in the next part of this article. The carrying capacity of the new construction of the hood is verified by a numerical analysis. The results of the new construction are compared with the original construction of the hood

非線形動的解析を用いた鉄道車両構体の塑性領域を含む長手方向強度評価

In recent years, much dynamic analysis and structural analysis have been done while considering abnormalities, such as derailment and collisions with foreign objects. In such situations, longitudinal force that exceeds design load may be applied to the car body and the ultimate load, also known as the buckling load and the crippling load, are more important than the design load that stipulates elastic strength. This is because a buckling load is the maximum load that a structure can sustain its soundness in the event of an accident. In this paper, the longitudinal strength of a railway vehicle is evaluated in consideration of plastic deformation. First in order to evaluate the strength of the railway vehicle body experimentally and validate the finite element (FE) model for the numerical simulations, the full scale crash test is conducted. Next the numerical simulations were conducted to investigate the relationship between the ultimate load and the design load, and effects on the buckling locations caused by load conditions such as dynamics and load path. As a result, it is clarified that existing vehicle structures have much larger longitudinal ultimate strength than elastic strength as defined in standards. Finally the ratios of the ultimate load to the design load are clarified, quantitatively.

Hybrid Skyhook-Stability Augmentation System for Ride Quality Improvement of Railway Vehicle

This paper is aimed to show the improvement of ride quality of railway vehicle with semi-active suspension systems. The dynamics of nine degrees-of-freedom (9-DOF) railway vehicle model is developed consists of a vehicle body, two bogies and four wheel-set. The disturbance considered is track irregularity which is modelled as a sine wave. The control algorithm for the semi-active suspension system is developed based on Stability Augmentation System (SAS) integrated with skyhook controller to reduce the effect of track disturbance. The performances of passive and semi-active suspension are compared by simulation using MATLAB-SIMULINK software. The results of the study show that the proposed controller is able to significantly improve ride quality of railway vehicle body. It is also noted that the additional ride control loop which is skyhook control is able to further improve the performance of SAS controller for the system.

H∞ control of railway vehicle suspension with MR damper using scaled roller rig

In this paper, a magneto-rheological (MR) damper was applied to the secondary suspension to reduce the vibration of a car body. The control performance of the MR damper was verified by numerical analysis with a 1/5 scale railway vehicle model in accordance with the similarity law. The analysis results were then validated in tests. In particular, the objective of the study was to understand how the control performance affected the dynamic characteristics of a railway vehicle and to systematically analyze the relationship between control performance and dynamic characteristics depending on various running speeds. To achieve this, experimental results for the dynamic characteristics of the scaled MR damper designed for the 1/5 scale railway vehicle model were applied to the railway vehicle model. The H∞ control method was applied to the controller. The means of designing the railway vehicle body vibration controller and the effectiveness of its results were studied.

Study on CMT Welding of Stainless Steel Railway Vehicle Body

Abstract. Cold metal transfer (CMT) process is a modified inert gas metal welding process,which characterizes of low heat input and no spatter welding comparing with traditional GMAW process.In this paper,research of the CMT welding features of stainless steel sheet has been conducted.The effects of welding parameters including wire feed rate,welding speed and arc-length modification coefficient on mechanical properties and surface morphology were investigated.In addition,optical micrograph(OM) and scanning electron microscope(SEM) were used to analyze the weld microstructure,and microstructural characteristics were discussed as well.In the end,the optimum welding parameters which were used in real production and achieved good effect were obtained by means of orthogonal experiment.

Robust system state estimation for active suspension control in high-speed tilting trains

The interaction between the railway vehicle body roll and lateral dynamics substantially influences the tilting system performance in high-speed tilting trains, which results in a potential poor ride comfort and high risk of motion sickness. Integrating active lateral secondary suspension into the tilting control system is one of the solutions to provide a remedy to roll–lateral interaction. It improves the design trade-off for the local tilt control (based only upon local vehicle measurements) between straight track ride comfort and curving performance. Advanced system state estimation technology can be applied to further enhance the system performance, i.e. by using the estimated vehicle body lateral acceleration (relative to the track) and true cant deficiency in the configuration of the tilt and lateral active suspension controllers, thus to further attenuate the system dynamics coupling. Robust H∞ filtering is investigated in this paper aiming to offer a robust estimation (i.e. estimation in the presence of uncertainty) for the required variables, In particular, it can minimise the maximum estimation error and thus be more robust to system parametric uncertainty. Simulation results illustrate the effectiveness of the proposed schemes.

NUMERICAL ANALYSIS OF THE FRONT IMPACT BETWEEN TWO SHUNTING LOCOMOTIVES

The main aim of this study is to carry out dynamic finite element analysis of a crash between two identical shunting locomotives. Numerical simulations include front-end impact of the running locomotive with a stationary one situated on the track. The first design collision scenario includes such obstacle for railway vehicles operated on national and regional networks. A considered locomotive based on a popular Polish shunting locomotive – SM42. However, the tested locomotive was slightly modernized in comparison with the original one. Finite element model of the locomotive was developed by the authors. FE analyses were carried out according to the PN-EN 15227 standard, which provides crashworthiness requirements for railway vehicle bodies. LESS-DYNA computer code was used for the simulations. The energy balance was initially checked in order to confirm the accuracy of analysis. The paper presents selected results of analyses focused on the locomotive frame behaviour. Contours of effective stress for selected moments of time are presented. Time histories of selected parameters are also depicted. The current study is a part of the project focused on modernization of the SM42 locomotive. Therefore, it is required to evaluate the locomotive behaviour during the impact test. Dynamic numerical simulation is acceptable since the experimental tests on the complete objects under consideration are impractical and impossible at the moment.

트랙좌표계를 이용한 철도차량의 동역학 해석에 관한 연구

Rail geometries such as cant, grade and curvature can be easily represented by means of a track coordinate system. In this analysis, in order to derive a dynamic and constraint equation of a wheelset, the track coordinate system is used as an intermediate stage. Dynamic and constraint equations of railway vehicle bodies except the wheelset are written in the Cartesian coordinate system as a conventional method. Therefore, whole dynamic equations of a railway vehicle are derived by combining wheelset dynamic equations and dynamic equations of railway vehicle bodies. Constraint equations and constraint Jacobians are newly derived for the track coordinate system. A process for numerical analysis is suggested for the derived dynamic and constraint equations of a railway vehicle. The proposed dynamic analysis of a railway vehicle is validated by comparison against results obtained from VI-RAIL analysis.

Sensitivity analysis to assess the influence of the inertial properties of railway vehicle bodies on the vehicle's dynamic behaviour

A sensitivity analysis has been performed to assess the influence of the inertial properties of railway vehicles on their dynamic behaviour. To do this, 216 dynamic simulations were performed modifying, one at a time, the masses, moments of inertia and heights of the centre of gravity of the carbody, the bogie and the wheelset. Three values were assigned to each parameter, corresponding to the percentiles 10, 50 and 90 of a data set stored in a database of railway vehicles. After processing the results of these simulations, the analysed parameters were sorted by increasing influence. It was also found which of these parameters could be estimated with a lesser degree of accuracy for future simulations without appreciably affecting the simulation results. In general terms, it was concluded that the most sensitive inertial properties are the mass and the vertical moment of inertia, and the least sensitive ones the longitudinal and lateral moments of inertia.

Substitution of corrugated sheets in a railway vehicle's body structure by a multiple-requirement based selection process

To simplify construction, reduce weight and improve mechanical properties, a sandwich panel substitution process is performed on corrugated sheets in the floor and roof of a rail vehicle car body. A requirement based selection is used to design the sandwich panels with the corrugated sheet mechanical characteristics as boundaries. Car body stiffness is evaluated by modal analysis. The derived panels reduce the mass of the car body by 600–700 kg. Results show the varying importance of the longitudinal, transverse and shear properties of the floor and roof panels, as well as how efficient the corrugated sheets actually are.

Active vibration suppression of lightweight railway vehicle body by combined use of piezoelectric actuators and linear actuators

In recent years, railway vehicle are becoming lighter because this corresponds not only to the improvement of the running speed but also to the reduction of running cost and environmental noise, especially for ultra-high-speed vehicle such as new Shinkansen and MAGLEV vehicle. However, this causes the deterioration of riding comfort. Bending vibration control method using piezoelectric actuators were proposed and good control performances were obtained through simulations and experiments. In this paper, active vibration control by combined use of piezoelectric actuators and linear actuators is investigated. Elastic vibrations are suppressed by piezoelectric actuators and rigid-body vibrations are reduced by linear actuators. Simulation studies and experiments using scale model were conducted and the effectiveness of the proposed control was confirmed.

C IV class tram crashworthiness assessment

The increasing number of accidents involving urban light rail vehicles makes the crashworthiness of this means of transport an issue of considerable importance. Simulations show that the new AnsaldoBreda Sirio-Milan tram fulfils the European crashworthiness requirements for railway vehicle bodies. The impact scenarios in prEN 15227 are less severe than those prescribed by Italian requirements for tramway and light rail system, UNI 11174. In this respect, an additional impact scenario is considered and structural changes to enhance the crashworthiness of the tram are proposed. Furthermore, the feasibility of a novel safety device intended to prevent serious injury to the driver even in the most severe of crashes is investigated.

Study on Car Body Tilting System Using Variable Link Mechanism (1st Report, Fundamental Characteristics of Pendulum Motion and Strategy of Perfect Tilting Condition)

This paper aims to analyze fundamental dynamic characteristics of tilting railway vehicle using variable link mechanism for compensating both lateral acceleration that passengers feel and wheel load imbalance between inner and outer rails. In this report, geometric relations between the center of rotation, the center of gravity, and the positions of all four links of tilting system are analyzed. Then, equations of the pendulum motions of railway vehicle body with four-link mechanism are derived. This paper theoretically discusses about the geometrical shapes of link mechanism that can provide zero lateral acceleration and zero wheel load fluctuation simultaneously. Then, “perfect tilting condition”, which is the control target of feedforward tilting control, is derived by linear equation of tilting motion.

A202 STUDY ON CAR BODY TILTING SYSTEM USING VARIABLE LINK MECHANISM : 1^<st> report, Fundamental Characteristics of Pendulum Motion

This paper aims to analyze fundamental dynamic characteristics of tilting railway vehicle using variable link mechanism for compensating both lateral acceleration that passengers feel and wheel load imbalance between inner and outer rails In this report, geometric relations between the center of rotation, the center of gravity, and the positions of all four links of tilting system are analyzed. Then, equations of the pendulum motions of railway vehicle body with four-link mechanism are derived. Then, "perfect tilting condition", which is the control target of feedforward tilting control, is derived by linear equation of tilting motion.