共查询到16条相似文献,搜索用时 203 毫秒
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为研究轮轨滚动接触疲劳(Rolling Contact Fatigue,RCF)载荷对铁轨表面裂纹应力强度系数的影响,以UIC60铁轨轮廓尺寸为依据建立轮轨接触的三维有限元模型,通过改变RCF载荷大小、轮轨表面摩擦因数和接触中心位置等轮轨接触的输入参数,计算铁轨表面接触裂纹尖端的应力强度系数,分析RCF载荷对铁轨表面接触疲劳裂纹的影响.结果表明RCF载荷作为控制铁轨表面接触裂纹的重要因素,其变化直接导致裂纹尖端应力强度系数的变化,从而改变裂纹的扩展状况.为减缓铁轨表面裂纹的扩展,可以针对载荷采取均匀分布载重量、使用润滑剂降低轮轨摩擦因数等相应措施. 相似文献
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利用当前通用的计算机编程技术,以高级编程语言VB为制作工具,以Origin7.0为作图工具,绘制了铸造Ti-6Al-4V钛合金疲劳裂纹扩展曲线.采用该编程技术,实现了参数的随机输入和曲线的动态形成,真实地制作了不同应力比下的疲劳裂纹扩展速率(da/dn)与裂纹尖端应力强度因子(△K)的关系曲线.同时该方法极大地提高了数据处理的效率及准确性. 相似文献
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本文基于ANSYS12.0平台,考虑当前铁路运输的高速、重载工况,对轮轨接触问题进行了有限元模拟计算。通过对轮轨之间的不同摩擦因数情况进行分析,得到了对于工程制造具有指导意义的合适的摩擦因数。对列车在水平直轨道和弯道上两种工况下进行分析知道,轮轨之间的横向挤压是不可忽略的,横向挤压是影响列车安全性的重要因素。 相似文献
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利用当前通用的计算机编程技术,以高级编程语言VB为制作工具,以Origin7.0为作图工具,绘制了铸造Ti-6Al-4V钛合金疲劳裂纹扩展曲线。采用该编程技术,实现了参数的随机输入和曲线的动态形成,真实地制作了不同应力比下的疲劳裂纹扩展速率(da/dn)与裂纹尖端应力强度因子(ΔK)的关系曲线。同时该方法极大地提高了数据处理的效率及准确性。 相似文献
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考虑到釉面膨胀系数对陶瓷表面微裂纹的影响,研究设计了一种陶瓷表面微裂纹扩展模拟方法.将釉面视为陶瓷基体材料中包裹的球状颗粒,基于球状颗粒半径趋于无穷大的情形,计算陶瓷材料与界面垂直的表面微裂纹的应力强度因子,然后分析热膨胀系数差对应力强度因子的影响并构建数字模型,建立符合Weibull分布的陶瓷表征单元体.从热传导和热膨胀系数等角度出发,模拟陶瓷表面微裂纹扩展情况.实验结果表明:裂纹扩展长度与膨胀系数成正比,当膨胀系数为10时,陶瓷试件表面微裂纹扩展迅速;陶瓷试件的水平方向应力随着膨胀系数的增加而增加;陶瓷表面微裂纹的长度与宽度与应力强度因子数值成正比. 相似文献
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为研究轮轨接触温升和热应力规律,用有限元法分别建立锥型踏面车轮和磨耗型踏面车轮在60kg/m钢轨上滑行的三维热接触耦合模型.考虑温度场与结构场相互影响、相关材料参数随温度变化以及轮轨接触问题,对在一定速度下抱死滑行时轮轨温度场和应力场的热一结构直接耦合进行分析.结果表明磨耗型踏面车轮的接触斑面积大于锥型踏面车轮的接触斑面积,且前者接触斑趋近于圆形,后者接触斑为细长椭圆形;材料参数随温度的变化对轮轨温度场和应力场影响很大,不可忽略;温度场对应力场的影响很大,温度升高的趋势与应力升高的趋势相同;磨耗型踏面对轮轨的热损伤比锥型踏面小很多. 相似文献
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G. Chattopadhyay V. Reddy P.-O. Larsson-Kråik 《International Transactions in Operational Research》2005,12(6):545-558
Rail players around the world have been increasing axle loads to improve the productivity of freight and heavy haul operations. This has increased the risk of surface cracks at curves because of rolling contact fatigue. Rail grinding has been considered an effective process for controlling these cracks and reducing risks of rail breaks. The complexity of deciding the optimal rail grinding intervals for improving the reliability and safety of rails is because of insufficient understanding of the various factors involved in the crack initiation and propagation process. This paper focuses on identifying the factors influencing rail degradation, developing models for rail failures and analyzing the costs of various grinding intervals for economic decision making. Various costs involved in rail maintenance, such as rail grinding, downtime, inspection, rail failures and derailment, and replacement of worn‐out rails, are incorporated into the total cost model developed in this paper. Field data from the rail industry have been used for illustration. 相似文献
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Important published papers on rail wear in the past were reviewed. A numerical method was put forward to predict curved rail
wear during a railway vehicle curving. The numerical method was discussed in detail. It considered a combination of Kalker’s
non-Hertzian rolling contact theory, rail material wear model, the coupling dynamics of the vehicle and track, and the three-dimensional
contact geometry analysis of wheel-rail. In its numerical implementation, the dynamical parameters of all the parts of the
vehicle and track, such as normal loads and creepages of the wheels and rails, were firstly obtained through the curving dynamics
analysis. The wheel-rail contact geometry calculation gave the wheel-rail contact geometry parameters, which were used in
the wheel-rail rolling contact calculation with Kalker’s non-Hertzian rolling contact theory modified. The friction work densities
on the contact areas of the wheels and rails were obtained in the rolling contact calculation, and were used to predict the
rail running surface wears caused by the multiple wheels of the vehicle simultaneously with the rail material wear model.
In the rail material wear model, it was assumed that the mass loss of each unit area was proportional to the frictional work
density in the contact area. A numerical example was present to verify the present method. The numerical results of the example
are reasonable, and indicate that the high rail wear of the curved track caused by the leading wheelset is much more serious
than those caused by the other three wheels of the same bogie. 相似文献
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Ali O. Ayhan 《Computers & Structures》2011,89(9-10):801-812
A three-dimensional methodology for simulation of fatigue crack propagation is presented. The method is leveraged by the use of enriched crack tip elements to compute the mixed-mode stress intensity factors. The crack growth model used and the crack propagation life calculation are also described. As examples, fatigue crack propagation of a mode-I surface crack and crack advancements of mixed-mode surface cracks are simulated. The predicted results showed excellent agreement with experimental data from the literature. Thus, it is concluded that the crack propagation method developed allows efficient and accurate simulation of three-dimensional fatigue crack propagation problems. 相似文献
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This paper presents a new method for modelling and simulation of the dynamic behaviour of the wheel-rail contact. The proposed dynamic wheel-rail contact model comprises wheel-rail contact geometry, normal contact problem, tangential contact problem and wheelset dynamic behaviour on the track. This two-degree of freedom model takes into account the lateral displacement of the wheelset and the yaw angle. Single wheel tread rail contact is considered for all simulations and Kalker s linear theory and heuristic non-linear creep models are employed. The second order differential equations are reduced to first order and the forward velocity of the wheelset is increased until the wheelset critical velocity is reached. This approach does not require solving mathematical equations in order to estimate the critical velocity of the dynamic wheel-rail contact model. The mathematical model is implemented in Matlab using numerical differentiation method. The simulated results compare well with the estimated results based on classical theory related to the dynamic behaviour of rail-wheel contact so the model is validated. 相似文献
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Wheel-rail contact elements incorporating irregularities 总被引:3,自引:0,他引:3
The aim of this study is to simulate the dynamic vertical response of a vehicle traversing rigid rails and a railway bridge. This is achieved by using the authors' wheel-rail contact element (WRC) to model the dynamic interaction that exists between a sprung wheel, using a Hertzian spring, and the rail. The objective in creating these elements was to model the rail and wheel irregularities, which was not a feature of the contact elements within the ANSYS finite element program. In this paper the numerical results generated using the authors' WRC element are identical to the results generated using the commercial contact element of ANSYS for a smooth rail condition. In the case of irregular rails, the numerical results generated using the authors' WRC elements compare very favourably with the results from the literature. 相似文献