土-结构动力作用体系混合试验研究进展与探讨

土-结构相互作用机制的研究通常需要借助试验方法来检验相关分析理论和模拟方法的合理性。混合试验是一种结合物理试验与数值模拟各自优势的试验方法,近年来发展迅速并逐渐向应用研究拓展,而土-结构作用体系是混合试验的一个重要应用领域。首先根据不同子结构对象对试验进行分类,分别归纳总结土体数值域-结构试验域、土体试验域-结构数值域、地层特性混合试验这3类土-结构作用体系混合试验的研究进展。从多跨桥梁结构、浅埋基础框架结构等传统土-结构作用体系,到液化场地桩基、海洋自升式平台、隧道-桩基-地上结构等复杂土-结构作用体系,混合试验为不同类型的土-结构动力作用体系的相互作用机制均提供了有效探究手段。笔者团队在强震作用下地下结构动力混合试验模拟方面的研究工作包括:在OpenSees-OpenFresco平台构建地下结构混合试验框架,以大开车站为例对试验框架进行验证,并对不同加载边界条件下的混合试验精度进行评价。研究结果表明:虚拟混合试验结果与纯数值模拟结果吻合良好;反弯点加载边界与完备加载边界的试验精度在小震工况(0.12g)下十分接近,但在大震工况下(0.58g)偏差较大。最后探讨了目前土-结构作用体系混合试验研究存在的共性问题,以期为今后混合试验的研究重点指明发展方向。     

Proposal for Testing and Rating of Traction and Stability Control Systems

Function and object of existing control systems for traction and stability are described. The problem of rating and objective evaluation of the influence of such slip control systems on vehicle dynamics is demonstrated. Closed-loop manoeuvres with subjective assessment and open-loop tests with measured data are shown. Analysis of correlation results in characteristic values which allow assessment of dynamic performance of slip control systems. Tests on natural and synthetic μ-low road surface with two passenger cars, equipped with different slip control systems, demonstrate the objective test method and show their results.     

基于模糊解释结构模型的客运交通结构优化方法

客运交通结构优化是实现城市交通系统可持续发展的重要方法之一,在提升城市客运交通系统效率方面发挥重要的作用.根据客运交通结构影响因素的性质,建立模糊解释结构模型,将客运交通结构的影响因素划分为4个层次:直接影响感知因素层、间接影响认知因素层、过渡连接因素层和根本性因素层,并使用有向弧对于层级之间与层级内部的影响因素关系进行了连接.根据模型的分析结果可知,城市规模为根本性因素,资金投入为过渡连接因素,道路布局、基础设施、出行者特性为间接影响认知因素.研究结果确定了优化客运交通结构的关键性因素,以哈尔滨市为实例,从交通政策、土地利用、出行方式效用等方面提出了优化城市客运交通结构的建议.      

Wheelchair accessibility of urban rail systems: Some preliminary findings of a global overview

Personal mobility is one of the fundamental human rights and it is vital to ensuring a productive and dignified life. It is estimated that there are more than 130 million people worldwide with a physical disability that requires the use of a wheelchair. In this context, public transport plays an important role, as a key element in guaranteeing equity in mobility and access to basic needs such as education, healthcare, employment and leisure. Urban rail systems represent an important medium and high-capacity mode of transport, largely used in daily journeys, especially within larger cities. Given the background, the aim of this article is to investigate wheelchair accessibility in urban rail systems around the world. In order to present this global overview, the official websites of the 212 urban rail systems in operation in 59 countries worldwide were consulted. The systems were classified into 7 different levels of accessibility, according to their percentage of declared adapted stations. The systems were then grouped per country and per United Nations geographical region, to enable an evaluation that takes into consideration different hierarchical perspectives. The results show that Eastern Asia, Western Europe and Northern America are the locations that have the highest number of systems. However, when it comes to accessibility, Northern America still has a very heterogeneous scenario, with a significant number of “Average” systems, while Asia and Europe together have more than half of the systems classified as “Very good” or “Fully accessible”. The presence of urban rail systems and the accessibility of those systems do not follow a strict pattern and some historical events are pointed to in order to try to explain the scenario. The study shows that there is still a long way to go when it comes to the accessibility of wheelchair users around the world and the lack of accessibility is not a problem only in developing countries.     

Self-Excited Vibrations of Railway Vehicle with Dry Friction Units

Some results obtained during developing a new approach to analysis of conditions of self-excitation of lateral vibrations of railway vehicles as systems of variable structure are given in this article. Structure variability is conditioned by the state of constraints with dry friction. An idea of the replacement of a nonlinear multibody system by a number of subsystems, which are linearized in a certain way, is worked out. The efficiency of the method suggested for the determination of the characteristics of self-excited vibrations of active multibody systems with dry friction is illustrated by way of an example of the investigation of the dynamic behaviour of a freight car.     

H2 optimal control of disturbance-delayed systems with application to vehicle suspensions

Optimal control of systems with time delays among disturbances, such as vehicle suspensions, is a relatively simple but long-standing problem in time-delayed control. We consider the exact H₂ optimal control of systems with time-delayed disturbances and develop a computationally efficient approach for controller synthesis. We extend the Lyapunov-based H₂ norm computation to systems with time-delayed disturbances and then derive a concise formula to explicitly evaluate the sensitivity of the system H₂ norm with respect to controller gains. Thence, a set of necessary conditions for H₂ optimal control of such systems using static output feedback are obtained in the form of algebraic equations. Gradient-based methods are adapted to optimize the controller gains. The method is also extended to reduced-order and decentralized control. As an application, a passive suspension system for an eight-DOF four-wheel vehicle is designed via structured H₂ optimization. The results are compared with those of a design based on a Pade expansion for the time delays and a design obtained by neglecting the disturbance delays.     

交通运输与物流业、旅游业发展耦合协调度分析——以武汉市为例

研究城市交通与其他系统间的协调性问题具有重要意义.为研究交通运输与物流业、交通运输与旅游业发展的协调程度,构建反映3个系统发展水平的指标体系,在此基础上构建耦合协调度模型、分析系统间的耦合协调状况.以武汉市2010—2017年交通运输系统与物流业、旅游业发展为例,进行综合实证分析.结果显示,3个系统之间综合评价值总体上...     

Chaotic Motion of Wheels

Trolleys have wheels which can choose the direction of their rolling. Studying the motion of a wheel like this, we can often find periodic motions (“shimmy”) or even chaotic ones. It has also been experienced that the chaotic motions sometimes disappear quite unexpectedly. A strongly simplified model of these systems is analysed in the paper by means of the methods of bifurcation theory. Analytical and numerical results are shown to characterize the system, including simulation results. Similar behaviour can be found in more complicated systems as well, like the trailers or the nose-gears of aeroplanes. The development of the so-called transient chaotic motion is explained in these systems.     

Self-Excited Vibrations of Railway Vehicle with Dry Friction Units

SUMMARY

Some results obtained during developing a new approach to analysis of conditions of self-excitation of lateral vibrations of railway vehicles as systems of variable structure are given in this article. Structure variability is conditioned by the state of constraints with dry friction. An idea of the replacement of a nonlinear multibody system by a number of subsystems, which are linearized in a certain way, is worked out. The efficiency of the method suggested for the determination of the characteristics of self-excited vibrations of active multibody systems with dry friction is illustrated by way of an example of the investigation of the dynamic behaviour of a freight car.     

大跨径混合梁斜拉桥抗震体系及阻尼参数研究

为研究大跨径混合梁斜拉桥在不同抗震体系与阻尼参数下的抗震性能,本文以主跨385m的京杭运河泗阳桃源大桥为背景,对比结构在纵桥向无连接装置、设置粘滞阻尼器、设置弹性索三种体系下的抗震能力,并进行了粘滞阻尼器与弹性索的设计参数敏感性分析,比较了不同参数下桥梁关键部位的地震响应变化,研究了不同体系下地震力传力路径。结果表明：选择合理阻尼参数与减隔震支座参数,可以大幅减小关键位置位移和关键构件内力,提高桥梁抗震性能。最后,给出了背景工程的合理设计参数,为同类型结构的抗震设计提供参考。     

车身覆盖件冲压仿真结果对比及分析

本文采用两个大型板料成形仿真软件Ａｕｔｏｆｏｒｍ和Ｌｓ－ｄｙｎａ３Ｄ作为隐式求解和显式求解的代表，就桑塔纳２０００型轿车处覆盖件－侧框进行了仿真计算对比。对比了两者在坯料成形后应变，厚度的变化以及比较了它们各自的应变状态与材料的成形极限图的裕度，确定了冲压成形中可能产生板料起皱和拉裂的区域。通过比较，讨论了两者在处理问题时存在的差异，分析了差异的原因以及减少差异的措施，探讨了两者各自的优缺点，并且     

Chaotic Motion of Wheels

Abstract

Trolleys have wheels which can choose the direction of their rolling. Studying the motion of a wheel like this, we can often find periodic motions (“shimmy”) or even chaotic ones. It has also been experienced that the chaotic motions sometimes disappear quite unexpectedly. A strongly simplified model of these systems is analysed in the paper by means of the methods of bifurcation theory. Analytical and numerical results are shown to characterize the system, including simulation results. Similar behaviour can be found in more complicated systems as well, like the trailers or the nose-gears of aeroplanes. The development of the so-called transient chaotic motion is explained in these systems.     

电流变智能半主动悬架模糊PID控制

对带有电流变液智能阻尼器的半主动汽车悬架系统设计了一种模糊PID控制器。将半主动悬架簧载质量的位移及其导数作为模糊控制器的输入，PID控制器的3个增益参数作为其输出，利用电流变液智能阻尼器的阻尼力可随电压变化的特性来使车身的振动降为最小。仿真实验给出了最优被动悬架、固定参数PID控制智能半主动悬架和模糊PID控制智能半主动悬架在不同路面激励情况下的响应曲线。     

CaPaSIM statement of methods

In the present paper, the method for calculation of the dynamic pantograph–catenary interaction developed by the Royal Institute of Technology and the Swedish National Rail/Road administration (Trafikverket) is described and the results of the benchmark exercise are discussed. The method is based on the commercial Finite Element software ANSYS. The geometry of the catenary and pantograph is defined in a pre-processor, BARTRAD, developed by Trafikverket, and is automatically translated into an ANSYS model. Basically all types of catenary systems could be handled as well as different types of non-linearity. There are both 2D and 3D versions of the code existing. The results achieved in this first stage of the benchmark are well in line with the results from the other partners in the benchmark study     

Hierarchical modeling of semi-active control of a full motorcycle suspension with six degrees of freedoms

Hierarchical control is a new control framework in the vehicle vibration control field. In this paper, a hierarchical modeling method is presented to form a different motorcycle model, compared to the traditional model with six degrees of freedoms (DOF), so as to construct hierarchical modeling control. The whole control framework is composed of a central control, two local controls and two uncontrollable parts. The front and rear wheel systems of a motorcycle are all dealt with by using two independent local 2-DOF systems. The driver and engine act as uncontrollable passive parts. The central control is composed of an algorithm made up of some dynamic equations that harmonize local relations. The vertical and pitch accelerations of the suspension center are treated as central control objects. With the help of Linear Quadratic Gaussian (LQG) algorithms adopted by two local controls, respectively, and Matlab software, some results of the simulation show that hierarchical modeling control requires less CPU time, reduces respond time and improves ride quality.     

New approaches to enhance active steering system functionalities: preliminary results

An important development of the steering systems in general is active steering systems like active front steering and steer-by-wire systems. In this paper the current functional possibilities in application of active steering systems are explored. A new approach and additional functionalities are presented that can be implemented to the active steering systems without additional hardware such as new sensors and electronic control units. Commercial active steering systems are controlling the steering angle depending on the driving situation only. This paper introduce methods for enhancing active steering system functionalities depending not only on the driving situation but also vehicle parameters like vehicle mass, tyre and road condition. In this regard, adaptation of the steering ratio as a function of above mentioned vehicle parameters is presented with examples. With some selected vehicle parameter changes, the reduction of the undesired influences on vehicle dynamics of these parameter changes has been demonstrated theoretically with simulations and with real-time driving measurements.     

Regenerative braking strategies,vehicle safety and stability control systems: critical use-case proposals

The sustainable development of vehicle propulsion systems that have mainly focused on reduction of fuel consumption (i.e. CO₂ emission) has led, not only to the development of systems connected with combustion processes but also to legislation and testing procedures. In recent years, the low carbon policy has made hybrid vehicles and fully electric vehicles (H/EVs) popular. The main virtue of these propulsion systems is their ability to restore some of the expended energy from kinetic movement, e.g. the braking process. Consequently new research and testing methods for H/EVs are currently being developed. This especially concerns the critical ‘use-cases’ for functionality tests within dynamic events for both virtual simulations, as well as real-time road tests. The use-case for conventional vehicles for numerical simulations and road tests are well established. However, the wide variety of tests and their great number (close to a thousand) creates a need for selection, in the first place, and the creation of critical use-cases suitable for testing H/EVs in both virtual and real-world environments. It is known that a marginal improvement in the regenerative braking ratio can significantly improve the vehicle range and, therefore, the economic cost of its operation. In modern vehicles, vehicle dynamics control systems play the principal role in safety, comfort and economic operation. Unfortunately, however, the existing standard road test scenarios are insufficient for H/EVs. Sector knowledge suggests that there are currently no agreed tests scenarios to fully investigate the effects of brake blending between conventional and regenerative braking as well as the regenerative braking interaction with active driving safety systems (ADSS). The paper presents seven manoeuvres, which are considered to be suitable and highly informative for the development and examination of H/EVs with regenerative braking capability. The critical manoeuvres presented are considered to be appropriate for examination of the regenerative braking mode according to ADSS. The manoeuvres are also important for investigation of regenerative braking system properties/functionalities that are specified by the legal requirements concerning H/EVs braking systems. The last part of this paper shows simulation results for one of the proposed manoeuvres that explicitly shows the usefulness of the manoeuvre.     

H 2 optimal control of disturbance-delayed systems with application to vehicle suspensions

Optimal control of systems with time delays among disturbances, such as vehicle suspensions, is a relatively simple but long-standing problem in time-delayed control. We consider the exact H ₂ optimal control of systems with time-delayed disturbances and develop a computationally efficient approach for controller synthesis. We extend the Lyapunov-based H ₂ norm computation to systems with time-delayed disturbances and then derive a concise formula to explicitly evaluate the sensitivity of the system H ₂ norm with respect to controller gains. Thence, a set of necessary conditions for H ₂ optimal control of such systems using static output feedback are obtained in the form of algebraic equations. Gradient-based methods are adapted to optimize the controller gains. The method is also extended to reduced-order and decentralized control. As an application, a passive suspension system for an eight-DOF four-wheel vehicle is designed via structured H ₂ optimization. The results are compared with those of a design based on a Pade expansion for the time delays and a design obtained by neglecting the disturbance delays.     

An overview: modern techniques for railway vehicle on-board health monitoring systems

Health monitoring systems with low-cost sensor networks and smart algorithms are always needed in both passenger trains and heavy haul trains due to the increasing need for reliability and safety in the railway industry. This paper focuses on an overview of existing approaches applied for railway vehicle on-board health monitoring systems. The approaches applied in the data measurement systems and the data analysis systems in railway on-board health monitoring systems are presented in this paper, including methodologies, theories and applications. The pros and cons of the various approaches are analysed to determine appropriate benchmarks for an effective and efficient railway vehicle on-board health monitoring system. According to this review, inertial sensors are the most popular due to their advantages of low cost, robustness and low power consumption. Linearisation methods are required for the model-based methods which would inevitably introduce error to the estimation results, and it is time-consuming to include all possible conditions in the pre-built database required for signal-based methods. Based on this review, future development trends in the design of new low-cost health monitoring systems for railway vehicles are discussed.     

桥道系结构形式对中承式钢管混凝土拱桥受力影响分析

在分析中承式钢管混凝土拱桥常用桥道系结构形式特点的基础上,首次提出一种新型的桥道系结构形式———简支连续组合桥道系,并运用大型结构有限元分析软件MSC Nastran进行数值仿真计算,研究不同桥道系结构形式对桥梁结构静、动力特征的影响。通过对比分析发现:不同桥道系结构形式对钢管混凝土拱肋的受力性能、结构的整体稳定性及动力性能的影响没有显著差异;简支连续组合桥道系较好地继承了简支和连续桥道系的优点,是中承式钢管混凝土拱桥的合理桥道系结构形式。