【作者】 熊小慧；

【导师】 梁习锋；

【作者基本信息】 中南大学 ， 载运工具运用工程， 2010， 博士

【摘要】 货车篷布是铁路货物运输的重要工具之一,在我国铁路运输中占有重要的地位。随着铁路客货列车运行速度的进一步提高,传统的篷布苫盖方式和篷布类型已经不能满足铁路提速的要求,为适应铁路客货大提速的需要,新型篷布、篷布绳索和篷布绳网大批量投入实际运营,新型材料的采用及其结构的改变,使其受力情况发生变化,需要提出新型篷布、篷布绳索和篷布绳网标准和技术条件。目前我国铁路篷布、篷布绳索和篷布绳网标准和技术条件主要依据国外相关标准和现场经验制定,迄今为止,国内外相关学者从未对复杂工况下铁路货车篷布受力情况进行过系统研究和综合试验。面临我国铁路货运的快速发展,亟待对复杂工况下铁路货车篷布、篷布绳索和绳网的受力情况进行全面分析和评估,为制定符合我国铁路运输实际的篷布、篷布绳索和篷布绳网技术指标和安全运行条件提供依据。本文通过实车试验和数值模拟计算相结合的方法,首次对复杂工况下铁路货车篷布、篷布绳索和绳网受力进行综合研究。主要研究工作如下：1、实车试验研究(1)开发了一套货车篷布、篷布绳索和篷布绳网气动力实车测试系统,实现了复杂工况下铁路货车篷布受力的实时测量；通过实车试验得到了货车篷布绳索、绳网在复杂工况下(包括通过大风地区、明线运行和交会、通过隧道和隧道内交会)的气动拉力和篷布应力,为制定篷布、篷布绳索和篷布绳网技术指标提供了科学依据；(2)得到货物装载方案、苫盖篷布类型、列车运行速度、横风风速、隧道断面、隧道长度及挡风设施对篷布、篷布绳索和篷布绳网所受气动力的影响规律。2、流场数值模拟研究(1)首次采用零厚度壁面模拟货车篷布,建立了各种复杂工况下篷布内外空间三维流场计算模型；得到货车在不同运行工况下篷布受到的气动升力,为进一步开展篷布强度计算提供依据；(2)得到了货车在大风地区运行时,货车运行速度、横风风速、货物装载高度、货物装载形状、货物沉降以及挡风设施对篷布气动力的影响规律；得到了货车通过隧道及隧道内交会时,货车运行速度、交会客车速度以及隧道断面面积对篷布气动力的影响规律；得到了货车明线运行及与客车明线交会时,货车运行速度以及交会车速度对篷布气动力的影响规律。3、篷布结构强度研究(1)建立了空气动力效应影响下的篷布结构强度分析模型,推导出索膜结构强度分析的索、膜非线性有限元求解方程。采用三角形等参膜单元模拟篷布,采用空间两节点索单元模拟篷布绳索,建立了索膜结构载荷分析模型；(2)采用基于计算流体动力学(CFD)和计算结构动力学(CSD)的准静态耦合方法对货车篷布强度进行了详细的受力分析。首先通过流场数值模拟技术得到复杂工况下货车篷布表面压力分布；其次通过所建立的篷布索膜结构强度计算模型,以篷布表面压力分布为加载载荷,运用非线性有限元分析方法对不同运行工况下的篷布气动载荷强度进行数值模拟计算；得到了泊松比、篷布绳索预张力、横风风速、货车速度以及交会客车速度对篷布强度的影响规律；(3)采用索膜结构分析理论对不同运行工况下的篷布强度进行校核,当货车160km/h明线运行和通过隧道、与动车组250km/h在明线和隧道内交会时,无绳网篷布所受最大主应力小于篷布许用应力,满足篷布安全运行要求；货车120km/h速度在大风地区运行,横风风速小于41.4m/s时,采用双层焊接结构的无网篷布所受最大主应力小于篷布许用应力,满足篷布安全运行要求；货车120km/h速度在大风地区运行,横风风速小于54m/s时,采用双层焊接结构的有防风网篷布所受最大主应力小于篷布许用应力,满足篷布安全运行要求。更多还原

【Abstract】 Tarpaulin of the freight car is an important tool for railway freight transportation, which plays an important role in Chinese railway transport. As the train speed rise, the traditional cover ways and the tarpaulin types can not meet the requirements of the railway development. In order to adapt the needs of the passenger and freight rail vehicle acceleration, new type of tarpaulin, tarpaulin rope and net have been put into actual operation. Because of the adoption of new materials, the structural and force of the tarpaulin, tarpaulin ropes have been changed. New standards and technical conditions of the tarpaulin and tarpaulin rope should been put forward.The standards and technical conditions of the tarpaulin and tarpaulin rope in Chinese railway had been set primarily based on the international standards and field experience at present. So far, domestic and foreign scholars have never carried out the systematic research and comprehensive test on the tarpaulin and tarpaulin rope when they had been used under the complex transport condition. With the development of the railway transportation in China, it is urgent to carry out a comprehensive analysis and assessment on the force of the tarpaulin and tarpaulin rope when the freight vehicle runs in all kinds of the worst working conditions. It should provide scientific basis for setting reasonable technical standards on the tarpaulin and tarpaulin rope of the freight vehicle in China.In this paper, the author have carried out a comprehensive study on the force of the tarpaulin and tarpaulin rope used the real vehicle test and numerical simulation method, when the tarpaulin and tarpaulin rope are used in different operating conditions, different loading conditions and different cover ways. The main contents and contribution of the dissertation are as follows:1. Real train test study(1) A real train testing system, which can test the aerodynamic force of the tarpaulin and tarpaulin rope, is developed. The author has carried out a real train test on aerodynamics force of the tarpaulin and tarpaulin rope for the first time at home and abroad. The maximum pull force of the tarpaulin rope and net and the maximum tarpaulin stress have been gained by real train test, when the freight vehicle covered with the tarpaulin run through the wind areas and the tunnel, pass by the other passenger vehicle in open air and in tunnel. It should provide scientific basis for setting reasonable technical standards on the tarpaulin and tarpaulin rope.(2) An effect law of the pull force of tarpaulin rope and the stress of the tarpaulin were gained, which caused by the scheme of the cargo loading, the type of the tarpaulin (D type tarp and X type tarp), the train speed, the speed of the side wind, the tunnel section, the tunnel length and the wind-break facilities.2. CFD numerical simulation(1) The complex three-dimensional flow field model around the tarpaulin were built when the fright vehicle runs through the wind area, runs and passes by the other passenger vehicle in the open air, runs through the tunnel and passes by the other passenger vehicle in tunnel. The zero-thickness wall was used to simulate the tarpaulin in those models.The aerodynamic lift forces were gained by CFD numerical simulation when the freight vehicle coved with tarpaulin operated in different conditions, such as wind area, passing by other passenger vehicle and through the tunnel et al. These lift force data would be used when the author studied the tarpaulin strength.(2) When the freight vehicle covered with tarpaulin run through the wind area, the effect laws of the tarpaulin aerodynamics force were gained which caused by the train speed, the speed of the side wind, the height of the cargo loading and the figure of the cargo loading, the sedimentation of the cargo and the wind-break facilities. When the freight vehicle covered with the tarpaulin run and passed by other passenger vehicle in the open air, the effect laws of the tarpaulin aerodynamics force were gained which caused by the train speed, the speed of passenger vehicle and the tunnel section. When the freight vehicle covered with the tarpaulin run and passed by other passenger vehicle in the tunnel, the effect laws of the tarpaulin aerodynamics force were gained which caused by the train speed and the speed of passenger vehicle.3 Tarpaulin structural strength study(1) A tarpaulin structural strength model influenced by the aerodynamic force was established. At the same time, the FEM solving equation of the cable and the membrane was derived when the cable and membrane structure strength analysis was studied. In the model, the triangle isoperimetric membrane unit was used to simulate the tarpaulin and the space two nodes cable element was adopted to simulate the tarpaulin rope.(2) The quasi static coupling method based on the CFD and CSD were used to study the tarpaulin structural strength. Firstly, the surface pressure distributions of the tarpaulin when freight vehicle operated in different conditions were gained by CFD numerical simulation. Secondly the numerical simulation on the tarpaulin structural strength caused by aerodynamic force were conducted when the freight vehicle covered with tarpaulin operated in different conditons.When the numerical simulation were done, the tarpaulin structural strength model influenced by the aerodynamic force was used and the tarpaulin surface pressure distribution were loaded on the model. Thirdly, the effect laws of the tarpaulin stress were gained which caused by the speed of passenger vehicle and the train speed.(3) The theory of the cable and membrane structure was used to check the tarpaulin strength under different operating conditions. When the freight vehicle run in the open air and through the tunnel with the speed of 160km/h, the maximum main stress of the tarpaulin without the cord is less than the allowable stress of the tarpaulin. When the freight vehicle speed was 160km/h and passed by the CRH2 EMU with the speed of 250km/h in the open air and in the tunnel, the maximum main stress of the tarpaulin without the cord is less than the allowable stress of the tarpaulin, which can meet the requirement for safety operation. When the freight vehicle speed is 120km/h and the side-wind speed is less than 41.4m/s, the tarpaulin stress used the doubled-welded without the cord is less than the allowable stress of the tarpaulin, which can meet the requirement for safety operation. When the freight vehicle speed is 120km/h and the side-wind speed is less than 54m/s,the tarpaulin stress used the doubled-welded with the wind-break cord is less than the allowable stress of the tarpaulin, which can meet the requirement for safety operation. (4) The effect laws of the maximum main stress and the maximum displacement of the top of the tarpaulin were gained which caused by the Poisson’s ratio and the pre-tension force of the cord through the analysis method of cable and membrane.更多还原