防风网工程防撞措施研究

防风网工程是一种应用于港口露天煤堆场的环保构筑物,然而煤堆场内转运煤炭的货车数量多且出入频繁,给道路周边的防风网带来了安全隐患。文章分析了港区货车撞击防风网等构筑物事故发生的原因,介绍了防撞措施的设置原则,提出了刚性防撞、柔性防撞、绿化带防撞、夜间防撞等被动防撞措施。     

踏板车发动机吊架装置的设计

通过在摩托车整车性能测试系统上跑车,对HN125T-2摩托车发动机与车架刚性连接进行振动信号测试,分析发动机振动对车辆动态性能的影响,提出发动机与车架弹性连接的方案,设计合理的结构装置,并用相同实验方法和数据处理方法进行振动信号测试验证,最大限度地减小了发动机振动对车辆动态性能的影响。     

柔性托台对承载式车身汽车底盘拼合的影响研究

文章研究了柔性托台对承载式车身汽车底盘拼合的影响研究。包括传统汽车底盘拼合工艺和柔性托台汽车底盘拼合工艺。结果表明柔性托台相较于传统汽车底盘拼合工艺,有着一次性投资高;但托台设计简单,拼合精度高,台面支撑少,便于实现自动拼合及紧固的优点;解决不同车型共线难题,使总装车间生产制造更加高效,智能。     

Flexible Overlap Technology for the Lining Trolley of Single-track Railway Tunnels北大核心CSCD

Falling-off of rock piece at tunnel arch and invert heave are the main potential safety problems affecting normal operation of the railway tunnel. The reasons causing falling-off of rock piece include squeezing by lining trol⁃ ley at construction joint, concrete cutting by cantilever end of water stop at construction joint, construction cold joint at arch, concrete quality deficiency and so on. To eliminate the falling-off of rock piece at tunnel arch caused by rig⁃ id overlap, modification of lining trolley and the flexible overlap technique combining tray with rubber gasket were adopted during the construction of Nuwashan tunnel on China-Laos railway, and the potential quality problem due to rigid overlap at construction joint of tunnel lining were effectively solved. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

机器人控制系统在整车焊装车间的扩展应用

文章研究论述的是工业机器人控制系统在整车焊装车间的扩展应用,应用于非常规工业机械手的工况。通过提供在整车焊装车间中的运动控制的若干解决方案,解决特定工况下运动控制中存在的成本高、设备占地空间大、故障率高、维护困难等诸多困扰生产线投入运行的课题,以提高焊装车间的生产线技术水平。     

对AASHTO柔性路面加铺层设计方法的评述

系统总结了美国AASHTO指南中的加铺层设计方法,并对其进行分析评论,为完善我国半刚性基层沥青路面的加铺层设计方法提供借鉴.     

A methodology to derive the critical demand density for designing and operating feeder transit services

Feeder lines are one of the most often used types of flexible transit services connecting a service area to a major transit network through a transfer point. They often switch operations between a demand responsive and a fixed-route policy. In designing and running such systems, the identification of the condition justifying the operating switch is often hard to properly evaluate. In this paper, we propose an analytical model and solution of the problem to assist decision makers and operators in their choice. By employing continuous approximations, we derive handy but powerful closed-form expressions to estimate the critical demand densities, representing the switching point between the competing operating policies. Based on the results of one-vehicle and two-vehicle operations for various scenarios, in comparison to values generated from simulation, we verify the validity of our analytical modeling approach.     

高速铁路接触网吊弦断裂电气因素研究

基于Carson理论建立简单链型悬挂接触网电流分布模型;结合铁路现场的实际供流数据,分别对受流点位于跨中和跨端2种情况下的接触网各导线实际受流情况进行仿真计算;基于电致塑性效应理论,采用对断裂吊弦进行SEM形貌分析、成分分析及对新旧吊弦的金相组织进行对比观察等试验手段,研究吊弦断裂过程中电气因素的作用机理.结果 表明:...     

基于柔性夹具的回弹测量方法研究

针对薄板冲压成形中缺少方便可靠的回弹测量方法的问题,提出了一种基于柔性夹具的新型回弹测量方法。该测量方法以柔性夹具代替传统回弹测量中的刚性模具和刚性夹具,支撑点的位置和数目可以根据零件的特点任意调整,减小了零件过定位和夹紧力不均匀所带来的误差。应用该测量方法对某车型翼子板的回弹进行了测量,分析了支撑点数目、支撑点位置及零件放置方向对回弹测量精度的影响,并对测量误差进行了讨论。     

A finite element model for unbonded flexible pipe under combined axisymmetric and bending loads

Flexible pipes are key equipment for offshore oil and gas production systems, conveying fluids between the platform and subsea wells. The structural arrangement of unbonded flexible pipes is quite complex, encompassing several layers with polymeric, metallic and textile materials. Different topologies and a large amount of intricate nonlinear contact interactions between and within their components, especially because of the relative stick-slip mechanism during bending, makes numerical analysis challenging. This paper presents an alternative three-dimensional nonlinear finite element model that describes the response of flexible pipes subjected to combined axisymmetric and bending loads. To simulate the response of a flexible pipe under axial tension or compression combined with uniform curvature, an equivalent thermal loading is employed on the external sheath, which is modelled as an orthotropic thermal expansion material with temperature-independent mechanical properties. To assess the feasibility of the proposed model, the bending moment versus curvature of the finite element solution is compared with experimental results obtained in literature and good agreements are found between them. Detailed finite element results such as contact pressures, armour wire slip displacements and friction, normal and transverse bending stresses are also shown and compared with available analytical models.