电动助力转向系统滑模变控制技术研究

以电动助力转向系统中直流助力电机的控制器为研究对象，依据助力电机的数学模型，应用带观测器补偿的滑模变结构控制方法，设计了滑模变控制器，通过调节助力电机的电压，获得预期的输出电流。仿真结果表明，所设计的滑模变控制器使助力电机具有很好的动态性能，系统基本无抖动现象，实现了助力电机输出电流对目标电流的跟踪特性。     

单斜岩质地层重式挡墙抗滑移合理性设计

基于西南山地较为常见的单斜岩质地层上修建重力式挡墙的情况,通过对水平基底、倾斜基底、锚杆基础、台阶基础、加大埋置深度、台阶和锚杆联合基础六种基础处理方式进行经济技术对比,分析各种方案的优缺点,提出了合理化的基础抗滑移设计方案.     

地铁车站的土建与机电施工协调管理

地铁车站土建与机电的协调涉及多专业、多单位、多环节、多接口,当车站土建结构基本完成时,装修及各机电系统承包商将陆续进场施工,形成同一车站内有多个承包商同时施工的情况。该文总结了上海轨道交通9号线一期工程的实践,认为:有必要建立一套协调机制,使各项工作顺利有序地开展,节省施工时间,提高施工安装的质量,同时能避免返工,减少损失。     

基于接触非线性的自翻车FEA实现

基于FEA(Finite Element Analysis)接触非线性,利用ANSYS软件实现了改进的新型自翻车车体非线性静强度分析,突破了国内外因自翻车模型庞大,结构复杂,接触边界条件繁多而带来的有限元非线性分析的困难.分析过程中充分考虑了自翻车体倾翻机构、八字面挡铁、活动卸货门等关键构件间特有的接触情况,更切实际地模拟了倾翻机构的工作状态,减小了仿真分析的误差.细述了自动倾翻车体结构建模过程中接触部件间的细节处理.通过接触非线性分析计算,得到了关键位置的应力分布情况,车体结构静强度与刚度均满足设计要求.     

复合材料螺栓连接结构数值模拟研究

在实际工程中,复合材料结构连接方式常采用机械连接形式(螺栓或铆钉)来连结复合材料构件和金属构件,而其中尤以螺栓连接更为常见.如何运用有限元软件模拟螺栓连接结构是仿真计算的关键.本文采用ANSYS软件,建立了复合材料螺栓连接结构的三维有限元模型,采用不同的边界处理方法对该结构进行数值模拟,得到复合材料螺栓孔处的载荷,并将数值计算结果与试验数据比较,探求出了该结构螺栓孔处载荷数值模拟方法.采用接触+耦合的边界处理方式不仅能较准确的模拟复合材料螺栓连接结构,而且计算时间远小于完全采用接触时的计算时间,大大提高了工作效率.     

Multibody dynamics modelling of the freight train bogie system

Previous work in the railway technology laboratory at Virginia Polytechnic Institute and State University (Virginia Tech) focused on better capturing the dynamics of the friction wedge, modelled using three-dimensional rigid body dynamics with unilateral contact conditions. The current study extends the previous work to a half-bogie model treated as an application of multibody dynamics with unilateral contact to model the friction wedge interactions with the bolster and the sideframe. The half-bogie model was derived using MATLAB and functions as a three dimensional, dynamic, and multibody dynamics model comprised of four rigid bodies: a bolster, two friction wedges, and a sideframe assembly. This expanded model allows each wedge four degrees of freedom: vertical displacement, longitudinal displacement (between the bolster and sideframe), pitch (rotation around the lateral axis), and yaw (rotation around the vertical axis). The bolster and the sideframe are constrained to have only the vertical degree of freedom. The geometry of these bodies can be adjusted for various simulation scenarios. The bolster can be initialised with a pre-defined yaw (rotation around the vertical axis) and the sideframe may be initialised with a pre-defined pitch/toe (rotation around the lateral axis). The results of the multibody dynamics in half-bogie model simulation are shown in comparison with results from NUCARS^®, an industry standard in train-modelling software, for similar inputs.     

Simulation of dynamic interaction between train and railway turnout

Dynamic train–track interaction is more complex in railway turnouts (switches and crossings) than that in ordinary tangent or curved tracks. Multiple contacts between wheel and rail are common, and severe impact loads with broad frequency contents are induced, when nominal wheel–rail contact conditions are disturbed because of the continuous variation in rail profiles and the discontinuities in the crossing panel. The absence of transition curves at the entry and exit of the turnout, and the cant deficiency, leads to large wheel–rail contact forces and passenger discomfort when the train is switching into the turnout track. Two alternative multibody system (MBS) models of dynamic interaction between train and a standard turnout design are developed. The first model is derived using a commercial MBS software. The second model is based on a multibody dynamics formulation, which may account for the structural flexibility of train and track components (based on finite element models and coordinate reduction methods). The variation in rail profile is accounted for by sampling the cross-section of each rail at several positions along the turnout. Contact between the back of the wheel flange and the check rail, when the wheelset is steered through the crossing, is considered. Good agreement in results from the two models is observed when the track model is taken as rigid.     

龙门式双主梁架桥机施工抗风性能研究

为明确强风环境下架桥机的抗风性能,以龙门式双主梁架桥机为对象,利用ANSYS软件建模,采用有限元方法计算分析了不同风速下架桥机的整体稳定性,重点考察了架桥机在不同工作状态时结构由水平和竖向风荷载引起的反力,进而分析了架桥机整体的抗滑移性能和抗倾覆性能。结果表明:为确保架桥机在大风区的施工安全性,应该采取必要的防风措施,提出了在墩顶预埋钢筋与架桥机前支腿临时锚固、起重小车起吊适当重量等实用措施。     

多种破坏因素下舰船电力系统三维战损综合评估

分析武器攻击产生的4种主要破坏因素对设备的损伤机理,对船体和电力系统进行三维数字建模,采用Matlab编程进行蒙特卡罗模拟多种常规武器攻击。考虑多种破坏因素,提出武器多次命中时电力系统各部分损伤概率和损伤等级的计算方法。利用层次分析法确定权重,综合评估电力系统的损伤,提出电力系统的设计及防护建议。     

Mathematical modelling of train–turnout interaction

The paper proposes a mathematical model of train–turnout interaction in the mid-frequency range (0–500 Hz). The model accounts for the effects of rail profile variation along the track and of local variation of track flexibility. The proposed approach is able to represent the condition of one wheel being simultaneously in contact with more than one rail, allowing the accurate prediction of the effect of wheels being transferred from one rail to another when passing over the switch toe and the crossing nose. Comprehensive results of train–turnout interaction during the negotiation of the main and the branch lines are presented, including the effect of wear of wheel/rail profiles and presence of track misalignment. In the final part of the paper, comparisons are performed between the results of numerical simulations and line measurements performed on two different turnouts for urban railway lines, showing a good agreement between experimental and numerical results.