强风地区高速铁路接触线预坡度探讨

强风地区高速铁路接触网尚无成熟运营经验,相应的接触网设计方案也在探索中.经过有限元分析发现,在侧向风吹时,接触线正反定位竖直方向呈现一定高差,甚至会出现一定位器向上抬升、相邻定位器向下抬升情况,由此产生了接触线坡度,进而影响了弓网受流质量.本文针对该情况提出了预坡度新概念,将因强风产生的接触线坡度降低了1/2.经过弓网...     

Non-steady state modelling of wheel-rail contact problem for the dynamic simulation of railway vehicles

Abstract

This paper deals with the solution of the non-steady state wheel-rail contact problem. Firstly, the existing models are analysed and it is concluded that none of them have the computational efficiency and/or accuracy characteristics required to be used in a railway simulation programme. Following this, a new solution is proposed to the problem that allows obtaining sufficiently accurate results with a relatively low computational cost. During the development of the proposed method it has been assumed that only one type of creepage is variable with respect to the time. Further work is necessary to extend it to more general cases.     

Nonlinear modelling of high-speed catenary based on analytical expressions of cable and truss elements

Due to the intrinsic nonlinear characteristics and complex structure of the high-speed catenary system, a modelling method is proposed based on the analytical expressions of nonlinear cable and truss elements. The calculation procedure for solving the initial equilibrium state is proposed based on the Newton–Raphson iteration method. The deformed configuration of the catenary system as well as the initial length of each wire can be calculated. Its accuracy and validity of computing the initial equilibrium state are verified by comparison with the separate model method, absolute nodal coordinate formulation and other methods in the previous literatures. Then, the proposed model is combined with a lumped pantograph model and a dynamic simulation procedure is proposed. The accuracy is guaranteed by the multiple iterative calculations in each time step. The dynamic performance of the proposed model is validated by comparison with EN 50318, the results of the finite element method software and SIEMENS simulation report, respectively. At last, the influence of the catenary design parameters (such as the reserved sag and pre-tension) on the dynamic performance is preliminarily analysed by using the proposed model.     

Lateral load transfer and normal forces estimation for vehicle safety: experimental test

Knowledge of vehicle dynamics data is important for vehicle control systems that aim to enhance vehicle handling and passenger safety. This study introduces observers that estimate lateral load transfer and wheel–ground contact normal forces, commonly known as vertical forces. The proposed method is based on the dynamic response of a vehicle instrumented with cheap and currently available standard sensors. The estimation process is separated into three blocks: the first block serves to identify the vehicle’s mass, the second block contains a linear observer whose main role is to estimate the roll angle and the one-side lateral transfer load, while in the third block we compare linear and nonlinear models for the estimation of four wheel vertical forces. The different observers are based on a prediction/estimation filter. The performance of this concept is tested and compared with real experimental data acquired using the INRETS-MA (Institut National de Recherche sur les Transports et leur Sécurité – Département Mécanismes d’Accidents) Laboratory car. Experimental results demonstrate the ability of this approach to provide accurate estimation, thus showing its potential as a practical low-cost solution for calculating normal forces.     

Using the lead vehicle as preview sensor in convoy vehicle active suspension control

Both ride quality and roadholding of actively suspended vehicles can be improved by sensing the road ahead of the vehicle and using this information in a preview controller. Previous applications have used look-ahead sensors mounted on the front bumper to measure terrain beneath. Such sensors are vulnerable, potentially confused by water, snow, or other soft obstacles and offer a fixed preview time. For convoy vehicle applications, this paper proposes using the overall response of the preceding vehicle(s) to generate preview controller information for follower vehicles. A robust observer is used to estimate the states of a quarter-car vehicle model, from which road profile is estimated and passed on to the follower vehicle(s) to generate a preview function. The preview-active suspension, implemented in discrete time using a shift register approach to improve simulation time, reduces sprung mass acceleration and dynamic tyre deflection peaks by more than 50% and 40%, respectively. Terrain can change from one vehicle to the next if a loose obstacle is dislodged, or if the vehicle paths are sufficiently different so that one vehicle misses a discrete road event. The resulting spurious preview information can give suspension performance worse than that of a passive or conventional active system. In this paper, each vehicle can effectively estimate the road profile based on its own state trajectory. By comparing its own road estimate with the preview information, preview errors can be detected and suspension control quickly switched from preview to conventional active control to preserve performance improvements compared to passive suspensions.     

道岔区轮轨力转移与分配特性研究

道岔区复杂的轮轨接触状态决定了其轮轨力特性与一般线路相比存在较大的差异。利用空间轮轨接触几何关系理论和Hertz非线性弹性接触理论，研究道岔区车轮与同侧并列的2股钢轨同时接触的2点接触问题。依据2点接触时轮轨弹性压缩量计算每一接触点上的轮轨力，由此确定车辆侧向和直向通过时的轮轨2点接触范围以及轮轨力转移和分配特性。结果表明：2股钢轨上轮轨力转移和分配特性不仅与钢轨外形、轨顶高度和宽度有关，而且与车辆过岔方式有关；考虑轮轨2点接触后的计算方法，消除了单点接触轮轨力计算中轮轨接触点从一股钢轨转移到另一股钢轨上时引起的轮轨力突变，使得轮轨力变化更为平顺和真实。     

熟悉PSC检查中GMDSS缺陷降低船舶滞留风险

介绍GMDSS滞留缺陷的判定,列举了PSC检查中常见的滞留缺陷,并提出相关建议以期减少船舶的滞留风险。     

城市客车行驶工况数据分析

以济南城市客车行驶工况为研究对象，通过使用数据监测记录仪采集发动机的运行数据，利用以数理统计相关理论为指导的解析方法和应用计算机辅助软件Matlab，从整车动力性和经济性角度对车辆行驶工况进行详细的数据分析，并总结归纳出适合城市客车行驶工况的良好驾驶操作习惯。     

电动轮汽车车速与道路坡度估计

针对电动轮汽车车速与道路坡度估计问题,本文中基于纵向非线性动力学方程设计1阶扩张状态观测器对车速与坡度进行联合估计,分析了估计稳态误差;同时,采用带遗忘因子的递归最小二乘估计算法分离加速度传感器信号中的坡度信息,并设置了比例系数来融合两类坡度信息,最终得到道路坡度估计值。搭建MATLAB/Simulink-Carsim联合仿真平台进行变坡度路面仿真,并在实际坡道路面完成实车测试。仿真与试验结果表明,所提出的方法简单、可行。     

基于滑模自抗扰的电制动系统动态负载模拟

为精准模拟传动系弹性及齿隙作用下电制动系统非线性机械负载,提出了自适应模糊滑模自抗扰的测功机控制算法。首先,针对一款前驱电动汽车,建立融合感应电机模型的车辆及台架机电一体化模型,引入典型正常制动和防抱死制动控制作为测试对象。其次,构建扩张状态观测器估计台架系统未建模动态,以自适应模糊滑模控制测功机实时模拟高度非线性机械负载。最后,开展了制动控制策略台架测试的仿真研究。结果表明:提出的方法可精确模拟电制动系统动态负载,有效提高制动控制算法台架测试精度。