鐵道機(jī)車車輛相關(guān)英語(yǔ)翻譯-其他專業(yè)(編輯修改稿)
2025-02-24 01:26 本頁(yè)面
【文章內(nèi)容簡(jiǎn)介】 uce 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 pared with a reference wheel. Concerning the interchangeability requirements in three ways are necessary depending on the customer1: * Functional requirements, . 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, . 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 bined 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 5105 and prEN 139791 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 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 pared with the decision criteria, which are 177。180 MPa for wheels with fully machined web and 177。145 MPa for wheels with unmachined web. In addition to the calculation fatigue tests can be required. This depends on
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