铁道机车车辆相关英语翻译.docVIP

Cut wheel fracture problems and maintenance costsJorg 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. RequirementsAs 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 leaflet 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 giving more 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 for 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 verificationThe stress ranges for the various designs are calculated as follows:* Wheel 21.061.00 (BA 004)/21.061.10 (BA 304) 240.9 MPa (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 Radsatzfabriks 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。 In the late 1960s and 1970s axel loads and speeds of railway vehicles increased rapidly.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。 This led to higher thermal an mechanical loads of the wheels.这导致了机械车轮要承载更高的热负荷。 轮箍Tiered wheels showed loose tyres after strong heating during runs on mountainous lines or following to brake irregularities.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。Maintenance costs for tyre changing increased more and more.维修费用为换轮箍的增加而越来越多。 In order to solve these problems solid wheels were introduced.为了解决这些问题，发展出了整体车轮。 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).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，Following the extended use of solid wheels in connection with a block brake, the unforeseen problem of wheel fracture occurred.随着陆 ，车轮断裂这一不可预见的问题发生了。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.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。 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 (see Table 2).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。Detailed investigation showed that all failured wheels were thermally damaged and had high residual tensile stresses in the rim of about 300 MPa.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。Though the number of failed wheels was relatively small each failure could lead to devastating consequences.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。 Therefore intensive research work was carriued out to improve this situation.因此,深入研究工作被提出来以改善这种状况。 Research programmme研究过程The European Rail Research Institute (ERRI), which is part of the UIC, was selected to lead the project work.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。The committee responsible for the work was the B 169 specialists committee.该委员会负责的工作是B169专家委员会。Three major problems were considered work programme:三大问题分别审议的工作方案：* Monitoring of the wheels in service.*维护中监测车轮；* Improvement of material characteristics.*改善材料的特性；* Iimprovement of the residual stress level and the displacement behaviour.*改善残余应力等级和横向稳定性。 针对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.针针对性第一个问题，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。 These investigations confirmed the results concerning the residual stresses.这些调查确认的结果就残余应力。 Table 3 shows an example for the residual stress distribution in the wheel rim 1.Approximately 10 per cent of the wheels had residual stresses of about 300 MPa.大约有百分之十的车轮残余应力约300兆帕。On the other hand, the fracture toughness KIC or KQ of the wheels investigated was between 40 and 70 MPam.在另一方面, 被调查的车轮断裂韧性KIC或KQ值在40至70兆帕之间。From fracture mechanics calculation it could be concluded that approximately 10 per cent of the wheels had a potential risk of failure 2.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 。 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 costs1.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。 Therefore the first step was to set-up rules for monitoring of the wheels in service including acceptance criteria.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.BB169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Criteria for the assessment of the wheels undergoing maintenance were also defined.现行定义。Wheels with thermal damages must undergo residual stress measuring and, if required, crack detection.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。The whole procedure is defined in4.整个程序被定义为四个阶段。Following to the implementation of the in-service rules and the continuous monitoring an essential reduction of wheel fracture was reached in Europe.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已洲 裂。 。 In order to be independent from detailed maintenance rules and in-service monitoring, research then focused on the improvement of the wheel material.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。 The results can be summarised as follows5:结果可以概括为以下几点： * Normally no KIC values were found, that are KQ values.*通常发现没有KIC值可查,只是KQ值； * KQ is suitable to describe the material characteristics,.*KQ是适于描述材料的特性；* KQ between 70 and 85 MPam is achievable for steel grade R7T.*KQ介于70至85兆帕之间，R7T级钢可以实现。 The third step focused on the reduction of the residual tensile stress level in the rim and on the lateral displacement of the rim.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。 In this regard the shape of the wheel web is essential.在这方面，轮辐的形状是十分重要的。 Therefore different proposals were developed by the wheel producers and were tested under the roof of the ERRI research programme.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。Generally it can be stated that a more flexible wheel web is suitable to reduce the residual tensile stresses in the rim.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。On the other hand it is also possible to hold the displacements in a small tolerance band.在另一方面，它也在小公差带范围内限制了位移。 Requirements要求 As a result of the research work, a number of new requirements for wheel material and wheel design were defined.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。These requirements led to new or revised international specifications.这些要求导致了新的或修订的国际标准。The material requirements are defined in UIC-leaflet 812-36 and recently in the European standard EN 132627.材料的要求,是指在UIC-单张812-36,最近又在欧洲标准EN132627中。For R7T steel grade (or ER7T according to EN 13262) a fracture toughness KIC or KQ of 80 MPam (mean value) and 70 MPam (minimum value) is required.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。ERFor ER6T the corresponding requirements are 100 MPam (mean value) and 80 MPam (minimum value) given in EN 13262.ERER6T 在EN13262中相应的要求是100Mpa(平均值)和80兆帕(最低值)。 Regarding the wheel design requirements the UIC published the new UIC leaflet 510-58 which was prepared by the ERRI B 169 specialists committee.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。This document is also the basis for the development of a new Draft European standard prEN 13979-1 which is in preparation now.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。The new standards are built up as a specification giving more freedom to the designer.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。According to these specifications four aspects of a new wheel design have to be considered:根据这些指标新的车轮设计有四个方面也必须考虑: * Geometrical aspect: to allow interchangeability.*几何方面:允许互换性； * Thermomechanical aspect: to manage wheel deformation and to ensure that braking do not induce wheel failure.*热应力方面:阻止车轮变形,以确保刹车不导制车轮失稳； * Mechanical aspect: to ensure that no fatigue crack in the web will occur.*力学方面:为确保无疲劳裂纹在辐板上发生； * Acoustical aspect: to ensure that the solution is better or equal compared with a reference wheel (informative).*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Concerning the interchangeability requirements in three ways are necessary