A review of dynamics modelling of friction draft gear

Longer and heavier trains mean larger in-train forces and more complicated force patterns. Practical experience indicates that the development of fatigue failure of coupling systems in long heavy trains may differ from conventional understanding. The friction-type draft gears are the most widely used draft gears. The ever developing heavy haul transport environment requires further or new understanding of friction draft gear behaviour and its implications for train dynamics as well as fatigue damage of rolling stock. However, modelling of friction draft gears is a highly nonlinear question. Especially the poor predictability, repeatability and the discontinuity of friction make this task more challenging. This article reviews current techniques in dynamics modelling of friction draft gears to provide a starting point that can be used to improve existing or develop new models to achieve more accurate force amplitude and pattern predictions.     

Coupler rotation behaviour and its effect on heavy haul trains

When a locomotive coupler rotates at an angle, the lateral component of the coupler force has an adverse effect on the locomotive's safety, particularly in heavy haul trains. In this paper, a model of a head-mid configuration, a 20,000-t heavy haul train is developed to analyse the rotation behaviour of the locomotive's coupler system and its effect on the dynamic behaviour of such a train's middle locomotive when operating on tangent and curved tracks. The train model includes detailed coupler and draft gear with which to consider the hysteretic characteristics of the rubber draft gear model, the friction characteristics of the coupler knuckles, and the alignment-control characteristics of the coupler shoulder. The results indicate that the coupler's rotation behaviour differs between the tangent and curved tracks, significantly affecting the locomotive's running performance under the braking condition. A larger coupler rotation angle generates a larger lateral component, which increases the wheelset's lateral force and the derailment coefficient. Decreasing the maximum coupler free angle can improve the locomotive's operational performance and safety. Based on these results, the recommended maximum coupler free angle is 4°.     

Freight cars shunting impacts analysis using an improved dynamic model of friction draft gear

In this study, simulations of shunting impacts for groups of freight cars that include up to six cars are considered. The simulation technique employs a white-box improved dynamic model of friction draft gear considering all its components and detailed finite element models of the freight cars. The key differences between the one-to-one shunting impact and the impact of long groups of cars in terms of features of the draft gear deflections and the coupler force time history are discussed. We present an example of dynamic finite element analysis for the car body using the coupler force time history obtained from the shunting impact simulation.     

关于内河危险品运输船舶事故应急预案的思考

分析目前危险品运输船舶所持事故应急预案存在的不足,提出规范格式、完善内容、加强审批把关等提高预案质量和实际效能的措施。     

超浅吃水肥大型船舶试验研究

超浅水 运餐蚨旨斗蚀笮驮嗣捍夜鞍宋濉惫ス叵钅俊Ｗ髡哒攵愿么吵运奶氐悖菘焖傩裕筒ㄐ杂氩僮菪缘囊罄慈范ㄆ渲谐叨龋⑸杓屏巳智疤逑吆退闹趾筇逑咝停辛硕嘀址桨缸楹显谘乖睾吐刈刺碌淖枇Α⒆院绞匝榧拔膊课恢绷饕猿〔馐匝芯优选出适合我国港口航道的超浅吃水肥大型船舶的设计一型。实船试航结果表明，该船水动力性能优良，且阻力性能与模型试验 合     

应收票据账务处理例解

本文以企业收到的商业汇票为例,结合实际案例,对企业收到带息票据和不带息票据、票据利息计算、票据贴现以及票据到期的账务处理进行阐述和解析。     

应收票据账务处理例解

本文以企业收到的商业汇票为例,结合实际案例,对企业收到带息票据和不带息票据、票据利息计算、票据贴现以及票据到期的账务处理进行阐述和解析。     

汽车用油压开关防水研究

油压开关常见的故障是由于水或其他杂质进入开关内部导致的触点接触不良或无法接通。通过增强密封可以防止水或杂质的侵入。但由于油压开关的原理是通过膜片两侧油压和大气压的平衡来工作的,不能将开关内部与外界完全隔离开来,所以,防水与通气成为矛盾。通过安装位置和方向设计,点突式、护套式结构设计,以及增加防水通气膜等设计方案,能够在确保压力平衡的情况下,有效防止水和杂质的侵入,提高油压开关的可靠性。     

我国重载货物列车缓冲器设计参数研究(待续)

介绍了影响缓冲器设计参数的因素,包括车辆结构及车辆强度、列车运行工况和编组调车工况等,确定了我国重载货物列车缓冲器设计参数的目标值,并阐述了新型重载货物列车缓冲器的方案设计.     

摩擦型缓冲器特性的数学描述

介绍了摩擦型缓冲器在车辆冲击过程中动态特性的特点和一种描述其动态特性的数学模型。进行车辆冲击过程仿真计算时,使用该模型可以更加真实地反映摩擦型缓冲器的动态特性。