仿生导轨耐磨机理与动态接触应力分析研究

发布时间：2018-03-17 01:25

本文选题：激光熔凝　切入点：HT300导轨　出处：《太原科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来,激光表面改性技术与仿生耦合学相结合,广泛应用于导轨耐磨性能的改善中,成为一个研究热点,但是至今尚且存在一些不足,对磨损过程中内部的应力分析还很模糊。(1)为了提高导轨的耐磨性能,本文对HT300材质的导轨进行了激光熔凝处理。分析了激光熔凝前后HT300材质的显微形貌、组织结构、显微硬度、弹性模量和3D磨损形貌,从显微组织和显微硬度两个层面总结了激光熔凝后耐磨机理。结果表明,HT300导轨经激光熔凝后生成的马氏体组织由于存在孪晶和位错,增强了材质抵抗塑性变形的能力。显微硬度比原来提高了3.11倍,使得磨损过程中硬化区的粗糙峰承载着主要的应力,减轻了基体所受应力。XRD实验结果得出石墨含量降低量占基体的40%,降低了裂纹萌生率。激光处理区域经过磨损后,锥刺、鳞尾、点蚀、剥落现象较未处理部位明显降低,裂纹扩展方向与摩擦方向呈45?-60?夹角,萌生源头为基体与熔凝组织的衔接部位。(2)设计出不同仿生试样,在相同的滚动干磨擦情况下进行磨损试验,结合磨损失重情况和3D形貌得到最大化改善导轨耐磨性能的仿生织构。在仿生织构形状相同的前提下,硬化区体积越大耐磨性越强,主要归因于高硬度值。在织构体积相同的前提下,不同类型的织构在磨损过程中的等效应力,最大剪应力,摩擦应力各不相同,因而耐磨性能也有所差异。(3)利用ansys workbench软件对非线性摩擦学问题进行了动态接触分析,从剪应力、等效应力、摩擦应力三方面分析了仿生导轨内部接触应力变化情况。动态接触分析结果表明试样块抗疲劳磨损的能力与实验结果分析中的变化趋势基本一致,仿生织构与摩擦方向所成的夹角越大,摩擦应力越小。模仿穿山甲仿生试样表面纹理织构的耐磨性能较与摩擦方向呈角度的耐磨性能强,仿生试样能够使接触表面摩擦应力变得平缓,从而使材料受力均匀。仿生织构的存在改变了运动部件的应力分布状态,降低了最大应力分布面积。其夹角处(即激光搭接部位)容易产生应力集中现象,而穿山甲试样的圆弧能够起到释放应力的作用,基于此得到了优化耐磨性能的方案:避免激光搭接产生应力集中和空洞现象,增加圆弧半径使应力得到释放,对以后导轨的仿生强化具有一定的指导意义。
[Abstract]:In recent years, laser surface modification technology combined with bionic coupling technology has been widely used in improving the wear resistance of guideway. In order to improve the wear resistance of the guide rail, the laser melting and setting treatment of the HT300 material is carried out. The microstructure, microstructure and microhardness of the HT300 material before and after the laser melting are analyzed, and the results are as follows: (1) in order to improve the wear resistance of the guide rail, the microstructure, microstructure and microhardness of the HT300 material before and after laser melting are analyzed. Elastic modulus and 3D wear morphology, the wear resistance mechanism after laser melting is summarized from two aspects of microstructure and microhardness. The results show that the martensite structure of the HT300 rail formed by laser melting is due to the existence of twinning and dislocations. The ability of material to resist plastic deformation is enhanced. The microhardness is 3.11 times higher than before, which makes the rough peak of hardening zone bear the main stress during wear. The results of XRD experiment show that the content of graphite decreases by 40% of the matrix, and the crack initiation rate decreases. After the laser treatment area is worn, the phenomenon of cone prick, scaly tail, pitting and denudation is obviously lower than that of the untreated part. The direction of crack propagation and the direction of friction are 45? -60? Different bionic samples were designed and wear tests were carried out under the same rolling dry friction condition. The bionic texture which can improve the wear resistance of the guide rail is obtained by combining the wear weight loss and 3D morphology. The larger the volume of the hardened zone is, the stronger the wear resistance of the hardened zone is, when the shape of the bionic texture is the same. Under the premise of the same texture volume, the equivalent stress, maximum shear stress and friction stress of different types of texture in the process of wear are different. Therefore, the wear resistance is also different. (3) the dynamic contact analysis of nonlinear tribological problems is carried out by using ansys workbench software, and the shear stress and equivalent stress are analyzed from the point of view of shear stress and equivalent stress. The dynamic contact analysis results show that the resistance to fatigue wear of the sample block is basically consistent with the change trend in the analysis of experimental results. The larger the angle between bionic texture and friction direction, the smaller the friction stress. The biomimetic specimen can smooth the friction stress on the contact surface and make the material under uniform stress. The existence of bionic texture changes the stress distribution of moving parts. The maximum stress distribution area is reduced. The stress concentration is easy to occur at the angle (that is, the laser lap position), and the arc of the pangolin specimen can release the stress. Based on this, the scheme of optimizing wear-resisting performance is obtained: avoiding stress concentration and void phenomenon in laser lap connection, increasing arc radius to release stress, which has certain guiding significance for bionic strengthening of guide rail in the future.
【学位授予单位】：太原科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG665

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