机车车辆相关英语翻译

Cut wheel fracture problems and maintenance costs
Jorg Villmann looks at the problems of wheel fracture and the development of new designs to reduce failure problems and maintenance costs.
In the late 1960s and 1970s axel loads and speeds of railway vehicles increased rapidly. This led to higher thermal an mechanical loads of the wheels. Tiered wheels showed loose types after strong heating during runs on mountainous lines or following to brake irregularities. Maintenance costs for type changing increased more and more. In order to solve these problems solid wheels were introduced. The most common used wheel type was the so-called ORE wheel developed by the European railways under the roof of the ORE (today European Rail Research Institute ERRI) as the research institute of the UIC (International Union of Railways).
Following the extended use of solid wheels in connection with a block brake, the unforeseen problem of wheel fracture occurred. Investigation of failured wheels showed that two principal forms of wheel fracture occurred - radial fracture from the wheel rim straight through the web down to the hub or beginning in the rim, running straight in to the web and shared in two branches. It was also found that the fracture was initiated from half-elliptical or fourth-elliptical fatigue cracks, which started on the tread, around the chamfer or due to sharp notches from clamping devices of reprofiling lathes.
Detailed investigation showed that all failured wheels were thermally damaged and had high residual tensile stresses in the rim of about 300 MPa. Though the number of failed wheels was relatively small each failure could lead to devastating consequences. Therefore intensive research work was carriued out to improve this situation.
Research programme
The European Rail Research Institute (ERRI), which is part of the UIC, was selected to lead the project work. The committee responsible for the work was the B 169 specialists committee. Three major problems were considered work programme :
* Monitoring of the wheels in service.
* Improvement of material characteristics.
* Improvement of the residual stress level and the displacement behaviour . With the first problem it was important to summarise the experience of the different railways and to get more detailed knowledge of the condition of the wheels in service. These investigations confirmed the results concerning the residual stresses. Approximately 10 per cent of the wheels had residual stresses of about 300 MPa. On the other hand, the fracture toughness KIC or KQ of the wheels investigated was between 40 and 70 MPa. From fracture mechanics calculation it could be concluded that approximately 10 per cent of the wheels had a potential risk of failure . The analysis also brought up some cases of fatigue cracks in the wheel web and many cases of unacceptable lateral displacements of the wheel rim leading to high maintenance costs.
Therefore the first step was to set-up rules for monitoring of the wheels in service including acceptance criteria. The B169 specialists committee developed four characteristics for visual inspection to identify potential wheels thermally overloaded . Criteria for the
assessment of the wheels undergoing maintenance were also defined. Wheels with thermal damages must undergo residual stress measuring and, if required, crack detection. The whole procedure is defined in 4. Following to the implementation of the in-service rules and the continuous monitoring an essential reduction of wheel fracture was reached in Europe. In order to be independent from detailed maintenance rules and in-service monitoring, research then focused on the improvement of the wheel material. The results can be summarized as follows5:
* Normally no KIC values were found, that are KQ values.
* KQ is suitable to describe the material characteristics,.
* KQ between 70 and 85 MPa is achievable for steel grade R7T.
The third step focused on the reduction of the residual tensile stress level in the rim and on the lateral displacement of the rim. In this regard the shape of the wheel web is essential. Therefore different proposals were developed by the wheel producers and were tested under the roof of the ERRI research programme . Generally it can be stated that a more flexible wheel web is suitable to reduce the residual tensile stresses in the rim. On the other hand it is also possible to hold the displacements in a small tolerance band.
Requirements
As a result of the research work, a number of new requirements for wheel material and wheel design were defined. These requirements led to new or revised international specifications. The material requirements are defined in UIC-leaflet 812-36 and recently in the European standard EN 132627. For R7T steel grade (or ER7T according to EN 13262) a fracture toughness KIC or KQ of 80 MPa (mean value) and 70 MPa (minimum value) is required. For ER6T the corresponding requirements are 100 MPa (mean value) and 80 MPa (minimum value) given in EN 13262.
Regarding the wheel design requirements the UIC published the new UIC leflaet 510-58 which was prepared by the ERRI B 169 specialists committee. This document is also the basis for the development of a new Draft European standard prEN 13979-1 which is in preparation now. The new standards are built up as a specification givingmore freedom to the designer. According to these specifications four aspects of a new wheel design have to be considered:
* Geometrical aspect: to allow interchangeability.
* Thermo mechanical aspect: to manage wheel deformation and to ensure that braking do not induce wheel failure.
* Mechanical aspect: to ensure that no fatigue crack in the web will occur.
* Acoustical aspect: to ensure that the solution is better or equal compared with a reference wheel.
Concerning the interchangeability requirements in three ways are necessary depending on the customer1:
* Functional requirements, e.g. wheel diameter, tread profile, asymmetry of the hub with regard to the rim.
* Fitting requirements, for example, length of the hub, bore diameter.
* Maintenance requirements, e.g. clamping conditions of the wheelset reprofiling lathes.
The designer has full freedom regarding the design of the wheel web.
For railway vehicles with block brakes the brake power has to be considered. Tests with freight trains running on long mountainous lines through the Alps received an average brake power level of 50kW for a wheel with 920mm diameter. For smaller wheels the brake power is on a corresponding lower level. Therefore wheels for freight wagons have to resist these brake loads.
For vehicles with different brake systems, such as disc brakes, an assessment of the thermal behaviour is not necessary. For combined brake systems (block brake and others) modified loads shall be agreed between customer and supplier. The brake loads are reproduced on a brake test bench. In order to check the thermal behaviour the wheel is loaded with a number of brake cycles. For the assessment unified criteria are defined in UIC 510-5 and prEN 13979-1 respectively. For the level of residual tensile stresses in the rim the following criteria are valid: For a wheel with its nominal diameter a stress level of maximum 200MPa (mean value) and maximum 250MPa (for each cross section) is acceptable. For a wheel with its diameter near the wear limit a stress level of maximum 275 MPa (mean value) and maximum 300 MPa is acceptable. Regarding the lateral displacement the analysis of maintenance rules, of the service experience and of the dimension of crossings and points led to allowable values between -1 mm and +3 mm (during braking) and between -0.5 mm and +1mm (in cold condition).
For the mechanical aspect8 determine a relative conventional procedure. First step is a stress calculation using the finite element method. Three conventional load cases are to be considered representing straight track full curves and points and crossings. Based on these loads the normal stresses for each node of the FE mesh is calculated. Comparing the stresses for the different load cases a stress range or a stress amplitude can be calculated. The stress of the most stressed node shall be compared with the decision criteria, which are ±180 MPa for wheels with fully machined web and 145 MPa f±or wheels with unmachined web. In addition to the calculation fatigue tests can be required. This depends on the results of the calculation and on the validity of the conventional loads. Two methods for fatigue tests are possible, either a random fatigue test or a one-stage fatigue test8. For both methods the test loads are derived from measured loads during field tests.
Concerning the acoustical aspect it is, of course, not a target that new developed wheels have higher sound radiation compared with existing designs. Therefore a sound level is described which is comparable with the former ORE standard wheels8. The sound level can be determined by a calculation. The acoustical requirements are informative only. Product development and verification
The stress ranges for the various designs are calculated as follows: * Wheel 21.061.00 (BA 004)/21.061.10 (BA 304) 240.9 MP±a (25 t axle load), * Wheel 21.431.01 (BA 378) 175.9±MPa,
* Wheel 21.430.01 (BA 375) 168.9±MPa,
* Wheel 21.463.00 185±.2 MPa (exceptional lateral forces for the calculation required).
Therefore for the wheel designs 21.061.00 (BA 004)/21.061.10 (BA 304)and 21.463.00 additional fatigue tests are necessary. The results of both fatigue tests and field tests showed sufficient mechanical characteristics.
Conclusion
Due to increased service loads especially increased thermal loads, Radsatzfabrik Isenburg GmbH developed a family of wheel designs for different applications. They meet the requirements of the new or revised specifications. Up to now no failure of these designs occurred. The residual stress level is lower compared with the former designs. Therefore the residual stress measurement during the maintenance can be cancelled. Due to the low lateral displacements no wheelset has to be replaced. The wheels meet the interchangeability requirements ensuring an easy change of wheels. The new designs help the customer to reduce maintenance costs. For the future modifications of Radsatzfabrik's designs are possible depending on specific customer requirements.
车轮断裂问题及维修费用
Jorg Villmann 研究车轮断裂问题, 开发新的设计, 以降低故障维修费用问题。

在60 年代末和70 年代铁路机车车辆重载和高速程度迅速提升。

这导致了机械车轮要承载更高的热负荷。

轮箍车轮在山区线路入下坡道反复制动运行时受到强热负荷出现松动。

维修费用为换轮箍的增加而越来越多。

为了解决这些问题，发展出了整体车轮。

最常用的轮型，是所谓的ORE车轮，是ORE下属的发达的欧洲铁路开发的（今天的欧洲铁路研究院ERRI），作为UIC（国际铁路联盟）的研究所。

随着整体车轮的进一步使用，由于制动的原因，车轮断裂这一不可预见的问题发生了。

调查裂损的车轮显示有两种主要损伤形式，车轮发生辐射状损伤，从轮缘直透过轮辐传给到轮毂或从轮辋开始，直线运行到轮辐上，并分成两个分支。

还发现是从半椭圆形或四椭圆疲劳裂纹开始
的，开始于踏面并围绕倒角处或由于车床侧面夹紧装置造成的尖锐缺口处展开。

详细的调查表明，所有裂损车轮均被热破坏，在轮辋处有较高的约300 兆帕的残余应力。

虽然失稳车轮数量相对较小，但是每次失稳可能导致灾难性的后果。

因此, 深入研究工作被提出来以改善这种状况。

研究过程
欧洲铁路研究院（ERRI），是欧洲铁路联盟的一部分，被选定承担这一项目工作。

该委员会负
责的工作是B169专家委员会。

三大问题分别审议的工作方案：
*维护中监测车轮；
* 改善材料的特性；
* 改善残余应力等级和横向稳定性。

针对第一个问题，重要的是要总结各种铁路运用经验并得到更详细的车轮维护状况的信息。

这些调查确认的结果就残余应力。

大约有百分之十的车轮残余应力约300 兆帕。

在另一方面, 被调查的车轮断裂韧性KIC或KQ直在40至70兆帕之间。

从断裂力学计算可以得出结论认为，大约有百分之十的车轮有潜在失稳的危险。

分析报告也提出了一些在轮辐处出现疲劳裂纹的案件和多例受侧位移的轮辋导致高维修费用的案例。

因此，第一步是设置规则的监测车轮的维护情况，包括验收标准.B169 的专家委员会，制定
了 4 个特色的目视检查，以确定潜在的车轮热负荷。

现行的车轮维修模式的评估标准也被定义。

车轮与热损失必须经过残余应力的测量，如果需要，还要进行裂缝检测。

整个程序被定义为四个阶段。

以下为在欧洲已贯彻了的现行制度和连续监测这对减少车轮失稳是至关重要的。

为了能独立于详细的维修制度和服务监控，当时的研究重点放在了改善车轮材料上。

结果可以概括为以下几点：
*通常发现没有KIC值可查，只是KQ值；
*KQ 是适于描述材料的特性；
*KQ介于70至85兆帕之间，R7T级钢可以实现。

第三步专注于减少轮辋及受外侧位移的轮缘处的残余应力的水平。

在这方面，轮辐的形状
是十分重要的。

因此，不同的方案，分别制定了车轮生产者并在欧洲铁路研究院研究方案下测试。

一般来说，可以这样说，一个更多变的轮辐是适于降低轮缘处的残余应力的。

在另一方面，它也在小公差带范围内限制了位移。

要求
由于此项研究工作, 一些新的要求, 车轮材料和车轮的设计作了界定。

这些要求导致了新的或修订的国际标准。

材料的要求,是指在UIC-单张812-36,最近又在欧洲标准EN132627中。

为R7T
级钢（或ER7T据为EN13262）断裂韧性KIC或kq80Mpa （平均数值）为70兆帕（最低值）是可用的。

ER6T在EN13262中相应的要求是100Mpa（平均值）和80兆帕（最低值）。

至于轮设计要求UIC发表新UIC规程510-58，是ERRI B169专家委员会所准备的。

这个文件也是此基础上制定了一项新的决议欧洲标准pren13979-1 即现在筹备工作。

这套新标准做为规范被建立，这为设计师们提供了更多的自由。

根据这些指标新的车轮设计有四个方面也必须考虑:
*几何方面: 允许互换性；
*热应力方面:阻止车轮变形,以确保刹车不导制车轮失稳；
*力学方面: 为确保无疲劳裂纹在辐板上发生；
*音质方面: 以确保解决办法是优于或等于参考轮。

从以下三个方面考虑互换性的要求是必要的:
* 功能要求, 如车轮直径, 踏面轮廓, 不对称轮毂, 轮缘；
*装配要求, 例如轮毂的长度, 孔径；
*维修要求, 例如轮轴在车床侧面的夹紧条件。

在设计轮辐方面设计师有充分的自由。

闸瓦制动的铁路机车车辆，制动功率应予以考虑。

货运列车在长大山区线路通过阿尔卑斯
山测试时，平均一个直径920mm的车轮.受到的制动功率为50kw。

对于更小直径的车轮这个制动功率是一个相对较低的水平. 所以货车的车轮要承担制动载荷。

车辆使用不同的制动系统, 如盘形制动, 评估的热性能是没有必要的。

联合制动系统（闸瓦制动及其他）改良负荷应达到客户和供应商的要求。

制动载荷在制动器试验台上被转载。

为了检测热性能，车轮上设置了一些制动周期。

为统一评估标准，制定了UIC510-5和PREN13979-1。

下面的轮辋中的残余应力标准是合理的：一个车轮的名义直径应力水平最高为200MPa（平均值）和最高250 MPa （每个截面）是可以接受的。

一个
车轮的直径接近磨损极限应力水平最高275兆帕（均值）最高300兆帕,是可以接受的。

关于侧移，分析维修规则的经验和在维和交叉及尖点的尺寸导致的允许值介于-1 毫米+3毫米（制动）之间，
及-0.5 毫米+1 毫米（在严寒条件）之间。

对机械外形的确定是一个相对常规的程序。

第一步是应力计算采用有限元方法。

三种常规的负荷被视为曲线和点的平交道口上。

基于这些载荷可以计算有限元网格的每个节点上的常规应力。

比较不同载荷工况下应力范围或应力振幅可以计算。

可以把应力最在点与标准进行比较, 其中完全机加工的车轮轮辐在± 180兆帕，非机加工的车轮轮辐在± 145兆帕。

除了计算，可以要求疲劳试验。

这将取决于计算结果和常规载荷的有效性。

这两种方法的疲劳试验是可能的, 要么是随机疲劳试验或一个阶段的疲劳试验。

对于这两种方法的试验荷载均来自实地试验的测定数据。

关于音质方面的资讯, 当然不是目标, 相比现有的设计新开发的车轮设计有更高的声辐射。

因此,车轮的音质水平应满足ORE标准。

声压级可以由计算得到。

音质所需的只是数据而已。

产品开发和验证
应力范围的各种设计计算方法如下：
*车轮21.061.00（ba100045）/21.061.10（ba304）±240.9 兆帕（25 吨轴重）；
*车轮21.431.01（ba378）±1759 兆帕斯卡；
* 车轮21.430.01(ba375) ±168.9MPa 时；
*车轮21. 463.00±1.852 兆帕(特殊的侧向力来计算的要求)。

因此对车轮设计21.061.00(ba100045)/21.061.10(ba304)21.463.00 额外疲劳试验是必要的。

结果双方的疲劳试验及实地试验表明有足够的力学性能。

结论
由于增加了服务量,特别增加了热负荷,Radsatzfabrik Isenburg GmbH开发一系列化的针对不同应用车轮设计。

他们符合要求的新的或修订的制度. 到现在为止这些设计并没有失稳发生。

相比以往的设计残余应力水平较低. 因此维修时残余应力的测量可以取消。

由于低侧移没有了更换轮轴。

车轮满足互换性要求, 确保更换车轮更加方便。

新的设计, 协助客户降低维修费用。

今后根据具体顾客的要求来修改Radsatzfabrik的设计变为可能。