The mechanism for the coupler and draft gear and its influence on safety during a train collision

A mechanical model of the coupler and draft gear was established to study the mechanism during an intercity train collision. The model includes four rigid bodies, one spherical joint, two nonlinear torsion spring units and two nonlinear hysteresis units. Simulation and test results show that the axial characteristics of the model are reasonable and the model can reasonably simulate the pitching movement of the coupler. The influence of the coupler and draft gear on the collision behaviour of the train is analysed considering a four-section intercity train. The results show that during the collision process, the amount of compression of the middle coupler is an important factor influencing the pitching deflection angle. The pitching motion posture of the coupler changes with the initial pitching deflection angle, but the initial pitching deflection angle has little effect on its yawing deflection angle. When the pitching angle of the middle coupler is elevated, as the elevation angle increases, the derailment risk of the ‘A’ end bogie of the previous vehicle increases, whereas the risk of derailment of the ‘B’ end bogie of the subsequent vehicle decreases. When the pitching angle of the middle coupler is depressed, the derailment trends for the front and rear bogies exhibit the opposite trend from that of the elevation angle. As the train collision speed increases, the pitching motion of the middle coupler is limited to forcing a yawing motion, causing the yawing deflection angle to increase sharply, which causes the wheel–rail lateral force to increase rapidly. From this, the derailment risk of the bogie increases, which further causes large displacement lateral buckling of the train. An anti-lateral buckling device can limit the yawing deflection angle of the middle coupler, preventing lateral buckling from large displacement and decreasing the risk of derailment.     

On the overriding issue of train front end collision in rail vehicle dynamics

A three-dimensional dynamic model of crashed vehicles coupled with moving tracks is developed to research the dynamic behaviour of the train front end collision on tangent tracks. The three-dimensional dynamic model consists of a crashed vehicle model, moving track models, a simple wheel–rail contact model, a velocity-based coupler model and the model of energy absorption and anti-climbing devices. The vector method dealing with the nonlinear wheel–rail geometry is put forward in the paper. The developed model is applicable in the scope that central collisions occur on tangent tracks at low speeds. The examples of the vehicle impacting with a rigid wall and the train front end collision are carried out to obtain the dynamic responses of vehicles. The overriding issue is studied on the basis of the wheel rise in train collisions. The results show that the second bogie of the first colliding vehicle possesses the maximal wheel rise. The wheel rise increases with the increase of vehicles. However, the number of vehicles has tiny influence on the overriding in train collisions at low speeds. On the contrary, the impact speed has significant influence on the overriding in train collisions. The wheel rise increases rapidly if the impact speed is close to the critical speed of overriding. The large wheel rise is principally generated by the great coupler force related to the rigid impact in the axial direction.     

Three-dimensional derailment analysis of crashed freight trains

In this paper, the collision-induced derailment of freight trains was investigated. The collision between two identical freight trains occurring on a curved path rather than along a straight line was investigated. This is because from the point of view of safety against derailment this collision scenario is thought to be more critical than the scenarios defined in the European standard EN 15227. In this work, one of the trains is stationary and the other moving train collides at 36 km/h. Two kinds of container wagons were simulated. One is the two-axle freight wagon Kls 442. Another is the freight wagon Rmms 662 with two Y25 bogies. Simulation results demonstrate that in terms of safety against derailment the bogie wagon Rmms 662 was found to have better behaviour than the two-axle wagon Kls 442. In addition, this study points out that there are many contributory factors to the responses of freight wagons during a collision, such as curve radius, distance between bogie pivots and loading mass. The derailment phenomenon is less likely to occur, when freight trains collide on the curve with a larger radius. Besides that the characteristics of freight wagons with large axle loads, low centre of gravity of car body and appropriate static strength are favourable for the collided wagons in reducing the risk of derailment.     

Dynamic simulation of train–truck collision at level crossings

Trains crashing onto heavy road vehicles stuck across rail tracks are more likely occurrences at level crossings due to ongoing increase in the registration of heavy vehicles and these long heavy vehicles getting caught in traffic after partly crossing the boom gate; these incidents lead to significant financial losses and societal costs. This paper presents an investigation of the dynamic responses of trains under frontal collision on road trucks obliquely stuck on rail tracks at level crossings. This study builds a nonlinear three-dimensional multi-body dynamic model of a passenger train colliding with an obliquely stuck road truck on a ballasted track. The model is first benchmarked against several train dynamics packages and its predictions of the dynamic response and derailment potential are shown rational. A geometry-based derailment assessment criterion is applied to evaluate the derailment behaviour of the frontal obliquely impacted trains under different conditions. Sensitivities of several key influencing parameters, such as the train impact speed, the truck mass, the friction at truck tyres, the train–truck impact angle, the contact friction at the collision zone, the wheel/rail friction and the train suspension are reported.     

Vibration control in train–bridge–track systems

To study the problems associated with vibration control of train–bridge–track systems a mathematical model with the capability of representing supplementary vibrational control devices is proposed. The train system is assumed as rigid bodies supported on double-deck suspension mechanism with semi-active features. The bridge system is modeled using the modal approach. Vibration control for bridge responses is provided by tuned mass dampers. A non-classical incremental Eigen analysis is proposed to trace the system characteristics across the time. In an example, the capability of the proposed model in investigating the vibration control prospects of a bridge–train system is shown. The results indicate the effectiveness of active suspension mechanism in reducing train's body movements, particularly the pitching angle and the vertical accelerations. Accordingly, the results also verify the potential of TMD devices in reducing the bridge responses at resonance motions.     

前置护体式安全座椅布置参数优化研究

建立了Q系列3岁假人的正面碰撞仿真模型,以前置护体安装高度位置(相对于假人H点位置)、前置护体自身高度、前置护体加强肋板刚度以及泡沫材料刚度4个因素为研究对象,运用正交试验设计和方差分析筛选优化参数,并采用基于遗传算法的多目标优化方法进行求解。经过优化求解得知,当前置护体安装高度位置为0 mm(相对于假人H点位置),前置护体自身高度为190 mm时,对儿童乘员的保护效果最佳。此时最大腹部压力较初始值降低了16.3%,胸部3 ms加速度较初始值降低了9.1%。综合分析可知,在正面碰撞中减小儿童腹部与胸部损伤的关键之处在于,前置护体需约束在儿童乘员的盆骨部位,避免在碰撞过程中儿童出现"下潜"现象;通过将约束部位扩散到儿童胸部的方式可以有效分散碰撞冲击载荷,从而减小儿童乘员的腹部和胸部损伤。     

顶置凸轮配气机构仿真分析

运用多体力学的方法对配气机构进行了动态仿真分析，采用数字多体程序的方法，建立了配气系统的理论模型，进行配气机构的运动学、动力学分析，除了得到气门的升程、速度、加速度外，还考虑了摇壁与气门之间的碰撞，以及摇臂支座的柔性。因此得到气门与摇臂之间的碰撞力，摇壁支座的柔性衬套的受力，气门弹簧力，凸轮轴支座反力，气门座反力及凸轮与摇臂之间的压力角等。为凸轮型线、摇壁形状和整个配气机的设计改进提供了重要依据。     

Vibration control in train-bridge-track systems

To study the problems associated with vibration control of train-bridge-track systems a mathematical model with the capability of representing supplementary vibrational control devices is proposed. The train system is assumed as rigid bodies supported on double-deck suspension mechanism with semi-active features. The bridge system is modeled using the modal approach. Vibration control for bridge responses is provided by tuned mass dampers. A non-classical incremental Eigen analysis is proposed to trace the system characteristics across the time. In an example, the capability of the proposed model in investigating the vibration control prospects of a bridge-train system is shown. The results indicate the effectiveness of active suspension mechanism in reducing train's body movements, particularly the pitching angle and the vertical accelerations. Accordingly, the results also verify the potential of TMD devices in reducing the bridge responses at resonance motions.     

横向激扰频率对上承式钢板梁桥横向振幅的影响

以跨度32m上承式钢板梁桥为例，针对桥梁的横向振动问题，将列车简化为移动质量建立了力学模型，应用大型软件MSC／DYTRAN进行了计算分析，研究了桥梁横向振幅与横向激扰频率的关系。通过计算分析，分别得到了在不同速度下模拟的空载货车和重载货车通过时桥梁的横向振幅与激振频率的关系，结果与实测值基本接近，这对通过快速计算确定引起桥梁横向拍振的蛇行运动频率具有创新和实用意义。     

Three-dimensional derailment analysis of a crashed city tram

City tram collisions are simulated using multi-body dynamics. The aim of this paper is to investigate the collision-induced derailment. Simulation results demonstrate that the corner obstacle collision scenario defined in EN 15227 is mainly focused on the energy absorption process. Due to the large impact angle (45°), it is unlikely for a city tram to comply with this scenario without derailment. In order to avoid derailment, the maximum impact angle between city tram and oblique obstacle should be reduced to 25°. Moreover, some influence factors are analysed, such as mass of loaded passengers, friction coefficient, impact angle, etc. Derailment phenomenon is shown to be significantly dependent on these parameters. Two measures are proposed to prevent the collided city tram from derailment. One is using secondary lateral dampers to absorb collision energy. Another is increasing the lateral stiffness of secondary springs as well as the lateral clearance, so that more collision energy can be stored in the suspension. With these measures, the safety against derailment can be improved.     

Development of motorcycle training simulator

From September 1996, motorcycle training schools have been required to introduce training to predict danger scenes in mixed traffic by using a motorcycle riding simulator. In order to obtain a high educational effect, it is necessary to reproduce the riding sense such as banking sense and pitching sense. Sensory evaluation was made on the said riding sense by using a simulator which has five degrees of freedom of roll, yaw, pitch, vertical direction and steer. The evaluation disclosed that the rotation center of roll and pitch largely influenced the banking sense and the pitching sense. The behavior of the newly developed simulator is controlled by three degrees of freedom of roll, pitch and steer, keeping similar riding sense to the simulator with four degrees of freedom.     

基于统计原理的铁路隧道运营期灾害类型及防灾对策研究

统计分析了83例国内外铁路隧道运营期事故资料,研究了铁路隧道运营期间主要灾害类型、原因及防灾对策。研究结果表明:1)铁路隧道运营期间主要灾害类型有火灾、列车碰撞、脱轨及衬砌剥落;2)铁路隧道运营期防灾应以隧道火灾为重点,同时兼顾列车碰撞、脱轨和隧道衬砌混凝土剥落等灾害;3)隧道内旅客列车火灾的主要原因为列车车辆关键部位故障、人为因素、列车车辆缺陷致列车碰撞或脱轨;4)依据土建设施规模及隧道结构分布特点,长大铁路隧道(群)运营期防灾模式可选择定点停车疏散救援模式、全长或局部范围内随机停车疏散救援模式;5)铁路隧道防灾涉及基础设施、铁道车辆和运输调度,应建立铁路隧道运营期灾害防范体系及预警系统,防止事故发生。     

Kinematic and dynamic analysis of the McPherson suspension with a planar quarter-car model

McPherson suspension modelling poses a challenging problem due to its nonlinear asymmetric behaviour. The paper proposes a planar quarter-car analytical model that not only considers vertical motion of the sprung mass (chassis) but also: (i) rotation and translation for the unsprung mass (wheel assembly), (ii) wheel mass and its inertia moment about the longitudinal axis, and (iii) tyre damping and lateral deflection. This kinematic–dynamic model offers a solution to two important shortcomings of the conventional quarter-car model: it accounts for geometry and for tyre modelling. The paper offers a systematic development of the planar model as well as the complete set of mathematical equations. This analytical model can be suitable for fast computation in hardware-in-the-loop applications. Furthermore, a reproducible Simulink implementation is given. The model has been compared with a realistic Adams/View simulation to analyse dynamic behaviour for the jounce and rebound motion of the wheel and two relevant kinematic parameters: camber angle and track width variation.     

小汽车与两轮车碰撞运动轨迹模型构建

应用碰撞动力学理论对小汽车与两轮车碰撞过程进行分析,分别构建了小汽车与两轮车碰撞后各自的运动轨迹模型,并运用自编软件实现车辆碰撞运动轨迹的再现仿真;选取碰撞事故案例,将求解结果与PC-Crash软件再现数据对比分析,结果表明模型可信度较高。     

Out-of-round railway wheels—a study of wheel polygonalization through simulation of three-dimensional wheel–rail interaction and wear

The objective of this study is to develop a tool for investigation of wheel tread polygonalization with radial irregularities including 1 to 20 wavelengths around the circumference of the wheel. Therefore, an existing multibody system model for simulation of general three-dimensional train–track interaction (accounting for frequencies up to several kHz) is extended with rolling contact mechanics according to FASTSIM. Furthermore, the model is also modified to allow for general wheel–rail profiles. The numerical model uses the concept of an iteration scheme including simulation of dynamic train–track interaction in the time domain coupled with a long-term wear model. A demonstration example including a bogie of a subway train travelling on a straight track is presented. In the example, an initial wheel out-of-roundness (OOR) is applied to the wheels. This irregularity is based on an amplitude spectrum derived from measurements on new wheels. Simulation results show that the most important wavelength-fixing mechanisms of the wheel OOR are (i) the vertical resonance of the coupled train–track system at approximately 40 Hz (the P2 resonance) and (ii) the frequency region including the lowest vertical track antiresonance at 165 Hz, where the dynamic track stiffness is high. Only a straight track is studied, but the model allows for asymmetric train motion on such a track.     

Modelling and handling dynamics of a wind-driven vehicle

This paper presents a study on the dynamic modelling of a land-yacht, i.e. a ground vehicle that is propelled by wind energy through the use of a vertical airfoil. First, a non-linear dynamic model of the land-yacht motion is derived using a compact matrix notation. Then, an introduction to the study of the performance and handling characteristics is presented. It is considered the vehicle response to input commands, i.e. steering to follow the desired course and adjusting the sail angle according to environmental conditions, that is, wind intensity and direction. The model demonstrates the performance in terms of maximum longitudinal speed and the effects on handling behaviour of the major vehicle design and operational parameters, including location of the centre of gravity and centre of effort, and forward speed, and it leads to conclusions of practical significance concerning directional control and stability.     

国内外汽车碰撞标准面面观

汽车碰撞标准是检验或评价汽车碰撞安全性能的重要依据，文章介绍了中、美、欧、日四方在汽车碰撞标准法规的差异，并对其进行了分析，同时重点讨论了我国在汽车正面碰撞标准、侧面碰撞标准和后面碰撞标准的制定情况。     

Human body modelling for traffic accident analysis

A traffic accident is a complex phenomenon with vehicles and human beings involved. During a collision, the vehicle occupant is exposed to substantial loads, which can cause the occupant injuries that depend on the level of passive safety, as well as on the occupant's individual characteristics. Correct estimation of injury severity demands a validated human body model and known impact conditions. A human body modelling procedure for the purpose of accident analysis is introduced. The occupant body has been modelled as a multibody system with rigid body segments connected. Geometrical and inertial properties of individual body segments were estimated using computed tomography. Frontal impact conditions were simulated on a sled test facility, while the human body dynamic response was measured. Comparison of experimental data and computer simulation revealed an influence of joint resistive properties on the occupant motion in collisions. The difference between measured and simulated response was minimised using optimisation method. Individualised human body modelling procedure enabled better prediction of the occupant motion during vehicle collision and thus more precise estimation of possible injuries in real-life traffic accidents.