【作者】 杨涛；

【导师】 孟凡明；

【作者基本信息】 重庆大学 ， 车辆工程， 2012， 硕士

【摘要】 发动机中的连杆轴承由于其工作条件恶劣，在使用中经常出现功率下降、过早磨损、疲劳断裂和润滑剂气化等失效现象。一个主要的原因是连杆轴承不能提供足够的承载力以平衡较高的连杆往复惯性力。随着微加工技术的发展，表面微造型方法以其能改善摩擦副性能的特点已得到密切的关注。已有的研究表明，合理的表面微造型设计能够提高摩擦副的承载能力，并减少接触表面的摩擦。本文立足于国家自然科学基金项目“表面微造型对大功率发动机连杆轴承摩擦学性能影响的研究”(项目编号50975297)，探讨利用微造型来改善发动机轴承的承载力、摩擦力、摩擦系数及应力等摩擦学性能。本文首先取一个微造型作为研究对象，建立了具有微造型的平行表面模型，并对其进行流固耦合分析。研究了微造型几何尺寸对平行表面承载力、摩擦力、摩擦系数及表面应力等摩擦学性能的影响。数值结果表明：微造型几何尺寸的合理变化会显著改善平行表面的摩擦学性能。微造型深度的减小，会降低微造型表面应力的波动，微造型表面应力幅值会随微造型宽度的减小而减小。接着，在上述研究基础上，对于小尺寸微造型，基于多相流理论，建立具有微造型的发动机轴承油膜气穴模型，并对其进行了CFD模拟，并研究了微造型位置对发动机轴承摩擦学性能的影响。研究表明：微造型位置对轴承摩擦学性能有显著影响，发现微造型布置最佳位置为轴承最大油膜压力区。进一步，基于发动机轴承的流固耦合模型，研究了微造型对发动机轴承静应力的影响，发现微造型可以减小发动机轴承的最大应力。最后，基于惯性释放的方法，分析了微造型对连杆瞬态性能的影响，发现微造型对连杆杆身动态应力影响较小。更多还原

【Abstract】 Poor working conditions result in frequent lubrication failures for theconnecting-rod bearing in a working engine, such as high frictional power, prematurewear, fatigue, lubricant cavitation and so on. One of main reasons is that theconnecting-rod bearing can not provide enough load-carrying capacity to balance thebig reciprocating inertia force of the connecting-rod.With development of micro-machining, the surface texturing is paid close attentionto due to its ability to improve performances for tribological pairs. Researches availableshow that the appropriate design of the surface textures can increase the load-carryingcapacity of tribological pairs, and reduce their friction.This paper is supported by the national natural science foundation for Effect ofSurface Dimple on High-power Engine Connecting Rod Bearing TribologicalPerformances (project no.50975297), which explores how to use the surface texture toimprove tribological performances of the connecting-rod, mainly including theload-carrying capacity, friction force, friction coefficient and stress for the enginebearing.First, take an example of a dimple, effects of dimple’s geometric sizes ontribological performances of parallel dimpled surfaces are analyzed with fluid-structureinteraction method, including the load-carrying capacity, friction force, frictioncoefficient and surface stress of the bearing. Numerical results show that the tribologicalperformances can be improved significantly with varied geometric sizes of dimples. Thefluctuation of the surface stress can be reduced through decreased dimple depth, and themaximum stress decreases with decreased dimple width.Then, numerical models of engine bearing with dimples are established based onmultiphase flow theories, and are analyzed with CFD method. Influences of the variedposition of dimples on the tribological performances for the bearing are investigated.The study shows that the tribological performances for the bearing are affectedsignificantly by the varied position of the dimple, and the optimum dimple position isfound to lie where the maximum film pressure of the bearing appears.After these, the finite element model of the engine bearing is estabished withfluid-solid interaction technique, and further effects of the dimple on static stresses forthe engine bearing are studied. The simulation results show that the dimples can reduce the maximum static stresses. Finally, effects of dimples on transient performances forthe connecting-rod are simulated based on the inertia release method. It is found thatdimple effect on dynamic stresses of the connecting-rod body can almost be neglected.更多还原