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1.
利用有限元法,考虑材料反复滚压条件下棘轮效应和局部滑动的影响,研究了非稳态机车和车辆车轮载荷作用下轮轨滚动接触的弹塑性应力、应变和变形,进而分析了塑性流动型钢轨波浪形磨损的形成和发展过程以及波谷和波峰处材料的力学行为.结果表明:在非稳态载荷作用下,钢轨接触表面产生不均匀塑性变形引起的波磨,波磨发展速率呈衰减趋势,最终趋于稳定状态;在相同载荷下,与车辆车轮相比,机车车轮对钢轨波磨影响较大;波谷处的残余应力、应变和变形大于波峰处.  相似文献   

2.
利用砂纸在钢轨试样表面打磨出不同粗糙度等级(1、4和7 μm)的单向磨痕和交叉磨痕(?45°/70°、?20°/90°和45°/70°),利用MMS-2A轮轨摩擦磨损试验机对打磨后的钢轨试样进行滚动试验并分析滚动接触疲劳损伤规律. 结果表明:打磨钢轨的滚动磨损表面粗糙度和损伤均比未打磨钢轨严重,随打磨磨痕粗糙度增加,钢轨滚动磨损表面粗糙度和损伤均呈减小趋势. 当打磨粗糙度为7 μm时,滚动接触疲劳裂纹为枝裂纹,裂纹深度较小;随打磨粗糙度减小,枝裂纹发生贯穿连通形成网状裂纹损伤,裂纹深度增加. 相较于单向打磨钢轨,交叉打磨磨痕钢轨滚动磨损表面粗糙度较低,滚动接触疲劳损伤较轻微. 此外,?45°/70°和45°/70°交叉磨痕的滚动损伤比?20°/90°交叉磨痕钢轨更加轻微.   相似文献   

3.
钢轨表面波浪形磨损研究   总被引:13,自引:3,他引:10  
通过对现场获取的波磨钢轨进行铆钉上,硬度试验分析,探讨了钢轨波磨的形成机理,发现钢轨波磨主要是因为轨面的不均匀塑性变形所致,机车车辆结构的相似和列车运行速度的趋近将加速钢轨波摩的产生,而提高钢轨屈服强度可有效地减轻钢轨波磨。  相似文献   

4.
激光离散处理车轮钢-钢轨钢摩擦副的摩擦学性能研究   总被引:1,自引:0,他引:1  
将激光离散处理前后的车轮试样分别与钢轨试样匹配,利用滚动接触摩擦磨损试验机测试各摩擦副的摩擦系数和磨损率,研究激光离散处理对轮轨摩擦副滚动接触摩擦磨损性能的影响.结果表明:车轮试样经过激光离散处理后,其抗磨损性能大幅增加,对应的轮轨试样摩擦副的摩擦系数小幅增加,其对摩钢轨试样的磨损加剧.未处理车轮试样主要发生剥层磨损并伴随轻微的疲劳磨损;处理后的车轮试样主要发生疲劳磨损并伴随轻微的剥层磨损.这是由于激光离散处理提高了车轮试样表层材料的抗塑性变形能力,从而抑制了材料的剥层磨损.各钢轨试样均发生剥层磨损,但是车轮试样经激光离散处理后,对应钢轨试样的剥层磨损加剧.  相似文献   

5.
曲线半径对钢轨磨损影响的数值计算与试验分析   总被引:2,自引:1,他引:1  
用数值计算方法详细分析了静态接触情况下,轮轨接触质点间蠕滑力、黏滑区的分布和摩擦功随曲线半径的变化,利用模拟试验研究了曲线半径对钢轨试样磨损特性的影响.结果表明:钢轨磨损量随曲线半径的增大呈非线性减小,在小于1 200 m的小曲线半径范围内,钢轨磨损量值随曲线半径的减小而急剧增大;随着曲线半径的增大,轮轨接触斑中最大滑动量逐渐减小,滑移区的面积减小,而黏着区的面积增大;轮轨接触斑上摩擦功随曲线半径的增大呈非线性的减小.  相似文献   

6.
轨下支承失效对直线轨道动态响应的影响   总被引:5,自引:0,他引:5  
建立了基于Timoshenko梁模型的车辆/轨道耦合动力学模型,分析轨下支承 失效对直线轨道动态响应的影响. 钢轨被视为连续弹性离散点支承上的无限长Timoshenko 梁,通过假设轨道系统刚度沿纵向分布发生突变来模拟轨下支承失效状态. 推导了考虑钢轨 横向、垂向和扭转运动的轮轨滚动接触蠕滑率计算公式. 利用Hertz法向接触理论和沈氏蠕 滑理论计算轮轨法向力及轮轨滚动接触蠕滑力. 采用移动轨下支承模型的车辆/轨道耦合系统 激振模式,考虑轨枕离散支承对系统动力响应的影响. 通过新型显式积分法求解车辆/轨道耦 合动力学系统运动方程,由数值分析计算得到不同轨下支承失效状态下直线轨道的动态响 应. 结果表明,轨下支承失效对直线轨道变形及加速度有显著的影响,随着失效轨下支承个 数的增加,轮轨相互作用力和轨道部件的位移、加速度将会急剧增大,将加速失效区段线路 状况的恶化.  相似文献   

7.
通过轮轨滚动接触模拟试验研究了干态、施加轨顶摩擦调节剂、润滑油和润滑脂工况下的轮轨摩擦、磨损和损伤行为,分析了不同润滑材料对轮轨滚动接触疲劳损伤的影响. 结果表明:施加轨顶摩擦调节剂可将轮轨摩擦系数调控至0.1~0.3范围内,车轮和钢轨试样磨损率较干态下分别降低了54.9%和26.3%,轮轨表面损伤、塑性变形和滚动接触疲劳损伤明显降低;施加润滑油和润滑脂具有更加显著的润滑和减磨效果,摩擦系数降低至0.1以下,磨损率降低85%以上,但润滑油和润滑脂会进入裂纹内部产生“油楔效应”,导致严重的滚动接触疲劳损伤,而轨顶摩擦调节剂的固体润滑特性则避免了该问题的产生.   相似文献   

8.
钢轨短波长波浪形磨损的安定性分析   总被引:7,自引:5,他引:2  
针对轮-轨滚动接触的短波长波浪形磨损现象,采用有限元法分析了三维实体模型的接触状态,通过计算分析了高频力作用下接触表面的塑性变形过程.结果表明:在一定的运动条件下,由于重复滚压作用,接触表面发生硬化并达到安定极限状态,生成有规律的短波长变形;钢轨表面塑性变形受枕木间距的影响;就具有随动硬化特性的钢轨材料而言,当摩擦系数μ<0.3时,屈服现象发生在材料表层下方;随着摩擦系数的增大,接触表面的切向力增大,安定极限的临界接触压力Po降低,屈服点移向接触表面,材料失效加快.  相似文献   

9.
应用轮轨型面测量仪测量实际运用中的磨耗后机车车轮,基于标准与磨耗后机车车轮型面,建立轮轨接触三维有限元模型,计算分析不同横移量下的接触斑和等效应力. 搭建轮轨接触试验台,使用取自现场的车轮与钢轨试块进行试验,分析不同横移量下轮轨接触状态. 针对磨耗前后车轮与标准钢轨接触的有限元计算与试验进行对比分析. 结果表明:横移量对轮轨接触状态有着显著的影响,横移量过大会加速机车车轮的磨耗;与标准型面相比,磨耗后车轮型面与标准钢轨接触时的接触斑面积较大,最大等效应力较小;通过轮轨接触试验台所得接触斑形状和大小与仿真计算所得结果一致性较好,证明了有限元仿真计算的可靠性.   相似文献   

10.
对高频轮轨相互作用下轨道的波浪形磨损问题进行了考察。通过引入轮轨的灵敏度,得到了轮轨间蠕滑力的波动同轨道表面不平顺幅值和表面曲率的波动关系;通过引入摩擦功计算了轨道表面的磨损,得到了磨损率的计算公式。结果表明,钢轨的磨损率同轨道的垂向动力行为密切相关;轨道表面不同点在不同激振频率下的磨损率不同。  相似文献   

11.
A calculation model is put forward to analyze the effect of a scratch on the running surface of a curved rail on initiation and growth of plastic deformation induced rail corrugation when a wheelset is steadily and repeatedly curving. The numerical method considers a combination of Carter’s two-dimensional contact theory, a two-dimensional elastic–plastic finite element model and a vertical dynamics model of railway vehicle coupled with a curved track. A concept of feedback between the corrugation development and the vertical coupling dynamics of the wheelset and track is involved. The cyclic ratchetting effect of the rail material under repeated contact loadings is taken into account. The numerical results indicate that when a vehicle runs on rails with a scratch the contact vibration between the wheel and rail occurs at large amplitude, and rail corrugation due to plastic deformation initiates and develops. The corrugation has a tendency to move along the running direction and its evolution rate decays as wheelset passages increase. The passing frequencies of the plastic deformation induced corrugation depend on the natural frequencies of the track. The residual stresses stabilize after a limited number of wheelset passages. The residual strains increase at a reduced rate with increasing wheelset passages.  相似文献   

12.
The effect of rail corrugation on the vertical dynamics of railway vehicle coupled with a curved track is investigated in detail with a numerical method when a wheelset is steadily curving. In the calculation of rail corrugation we consider the combination of Kalker‘s rolling contact theory modified, a model of material loss on rail running surface, and a dynamics model of railway vehicle coupled with a curved track. In the establishment of the dynamic model, for simplicity, one fourth of the freight car without lateral motions,namely a wheelset and the equivalent one fourth freight car body above it, is considered. The Euler beam is used to model the rails and the track structure under the rails is replaced with equivalent springs, dampers and mass bodies. The numerical results show the great influence of the rail corrugation on the vibration of the parts of the vehicle and the track, and the some characters of rail corrugation in development.  相似文献   

13.
As a vehicle passing through a track with different weld irregularities, the dynamic performance of track com- ponents is investigated in detail by using a coupled vehi- cle-track model. In the model, the vehicle is modeled as a multi-body system with 35 degrees of freedom, and a Timoshenko beam is used to model the rails which are dis- cretely supported by sleepers. In the track model, the sleepers are modeled as rigid bodies accounting for their vertical, lat- eral and rolling motions and assumed to move backward at a constant speed to simulate the vehicle running along the track at the same speed. In the study of the coupled vehicle and track dynamics, the Hertizian contact theory and the theory proposed by Shen-Hedrick-Elkins are, respectively, used to calculate normal and creep forces between the wheel and the rails. In the calculation of the normal forces, the coefficient of the normal contact stiffness is determined by transient contact condition of the wheel and rail surface. In the calcu- lation of the creepages, the lateral, roll-over motions of the rail and the fact that the relative velocity between the wheel and rail in their common normal direction is equal to zero are simultaneously taken into account. The motion equations of the vehicle and track are solved by means of an explicit integration method, in which the rail weld irregularities are modeled as local track vertical deviations described by some ideal cosine functions. The effects of the train speed, the axle load, the wavelength and depth of the irregularities, and the weld center position in a sleeper span on the wheel-rail impact loading are analyzed. The numerical results obtained are greatly useful in the tolerance design of welded rail pro- file irregularity caused by hand-grinding after rail welding and track maintenances.  相似文献   

14.
全制动工况下轮轨热-机耦合效应的分析   总被引:5,自引:2,他引:3  
采用有限元法从摩擦热效应角度探寻轮轨表面破坏的原因,建立了轮轨热-机械载荷耦合接触模型,分析纯滑动接触过程中轮轨的温升以及热应力,模型中考虑了轮轨间非稳态热传导、与环境的热对流和热辐射以及轮轨间的接触计算,分析了滑动接触过程中应力场的分布特点以及速度的影响.结果表明:所采用的接触算法能够求解二维轮轨全制动工况下的热接触问题;轮轨摩擦热效应只存在于表层,其影响随着深度增加而减小;轮轨的相对滑动速度越高,其热效应越明显.  相似文献   

15.
以工程实例为研究对象,建立了整车-整桥系统耦合振动数值分析模型。考虑车轮的跳轨和挤密情况,建立了单边弹簧-阻尼系统弹性轮轨接触模型。采用基于多体系统动力学和有限元法结合的联合仿真技术,计算了两种轮轨接触时动车组列车以不同车速通过大跨度连续桥梁的耦合振动响应。数值计算结果表明:两种轮轨接触模型的桥梁动力响应比较接近;列车的横向轮轨力、轮重减载率和脱轨系数相差较大,当速度为350km/h时,横向轮轨力增大了46.5%,轮重减载率增大了130.8%,脱轨系数增大了24.66%;用单边-弹簧阻尼系统弹性轮轨接触模型更符合实际。  相似文献   

16.
This paper develops a coupled dynamics model for a linear induction motor (LIM) vehicle and a subway track to investigate the influence of polygonal wheels of the vehicle on the dynamic behavior of the system. In the model, the vehicle is modeled as a multi-body system with 35 degrees of freedom. A Timoshenko beam is used to model the rails which are discretely supported by sleepers. The sleepers are modeled as rigid bodies with their vertical, lateral, and rolling motions being considered. In order to simulate the vehicle running along the track, a moving sleeper support model is introduced to simulate the excitation by the discrete sleeper supporters, in which the sleepers are assumed to move backward at a constant speed that is the same as the train speed. The Hertzian contact theory and the Shen- Hedrick-Elkins’ model are utilized to deal with the normal dynamic forces and the tangential forces between wheels and rails, respectively. In order to better characterize the linear metro system (LMS), Euler beam theory based on modal superposition method is used to model LIM and RP. The vertical electric magnetic force and the lateral restoring force between the LIM and RP are also taken into consideration. The former has gap-varying nonlinear characteristics, whilst the latter is considered as a constant restoring force of 1 kN. The numerical analysis considers the effect of the excitation due to polygonal wheels on the dynamic behavior of the system at different wear stages, in which the used data regarding the polygonal wear on the wheel tread are directly measured at the subway site.  相似文献   

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