【作者】 刘智；

【导师】 高诚辉；

【作者基本信息】 福州大学 ， 机械设计及理论， 2005， 硕士

【摘要】 工程实际中,摩擦热的产生将对重要工程表面造成严重的破坏,相互接触的摩擦滑动表面是粗糙的,因此对微区间工程粗糙表面的闪温和热-机械应力分析有着重要的理论意义。本文对粗糙表面的分形表征及其接触模型、粗糙表面闪温的研究现状及其发展方向进行了评述;基于三维分形理论建立了粗糙表面接触热传导模型,并对其摩擦滑动界面的传热规律进行了研究。基于三维分形理论,将工程粗糙表面摩擦生热问题简化为一具有分形特性粗糙表面的实体和一具有光滑表面的实体作相对滑动摩擦生热的问题。考虑了两个物体摩擦接触的热弹性耦合问题,并利用热-结构顺序耦合建立瞬态有限元计算模型,以制动器摩擦副材料为例,在有限元软件ANSYS的非线性有限元多物理场中进行模拟,对粗糙表面接触模型的瞬时摩擦温度场/压力场/应力场进行了计算分析。在数值计算过程中,着重考虑了微凸体之间的相互影响,温度变化与接触区域压力变化的耦合问题,最高温度、最大接触压力以及最大等效应力的变化问题。本文通过对具有分形特性粗糙表面接触模型的摩擦滑动三维瞬态温度场/压力场/应力场的耦合计算分析,揭示了粗糙表面滑动摩擦副的温度、接触压力和热应力的分布规律,以及摩擦界面间的热流分配规律;在考虑了微凸体之间相互影响的基础上分析了滑动过程中最高温度、最大接触压力、最大等效应力以及真实接触面积的变化规律和它们之间的相互影响;探讨了取样区间、滑动速度、外加压力、自然对流换热系数、比热容、导热系数、体积温度以及环境介质温度等参数的变化对闪温的影响。本文的计算分析结果为进一步研究粗糙表面摩擦副的闪温和热-机械失效问题以及磨损机理,开发高性能摩擦材料打下了良好的基础。更多还原

【Abstract】 In mechanical engineering, the frictional heat will cause serious destruction to the important engineering surface, the two surfaces in sliding contact are rough,so it have an important theoretical meaning to analyzing the flash temperature and thermal-mechanical stress of micro-scale of the engineering rough surfaces. This paper research on the fractal characterization and contact model of rough surfaces, current situation and developing direction of the rough surface flash temperature. Based on three-dimensional fractal theory, the heat- conduction contact model of rough surfaces was set up and the law of heat transfer between the sliding surfaces was studied.Based on three-dimensional fractal theory, two engineering rough surfaces in contact that produce frictional heat were simplified into a smooth one and a rough one which has fractal characteristic. Thermal-elastic problem of the two frictional contact bodies was considered, and established a transient thermal and stress coupled FEM model using thermal-structure sequential coupling. Taking brake materials as the example, the course of the sliding with friction was simulated in ANSYS software using the nonlinear multiphysics field FEM, to calculate and analyze the temperature, contact pressure and stress field of the sliding contact surfaces with frictional heating. In the course of numerical calculation, the influence among asperities, the coupling problems of the variation of temperature and pressure on contact surfaces, the variation problems of the maximum temperature, maximum contact pressure, maximum stress were taken account into.In this paper, the regulation of distribution of temperature and contact pressure and thermal stress and the division of heat between the sliding surfaces were showed through the coupled analysis to the three-dimensional transient temperature, pressure and stress field of rough surface which has fractal characteristic. Considering the influence among asperities, the regulation of variation and the influence among maximum temperature, maximum contact pressure, maximum stress and real contact area were analyzed. The separate effect of the sampling section, sliding velocity, applied pressure, the natural convection changes hot coefficient, specific heat, thermal conductivity, volume temperature and ambient temperature on the flash temperature were discussed. <WP=4>The results of this paper are the basic for further research on the flash temperature, thermal-mechanical problems and the wear mechanisms of the rough surfaces, also helps to develop the excellent frictional material.更多还原