扭动微动磨损损伤机理及防护的数值分析研究

发布时间：2018-02-22 22:40

本文关键词： 摩擦磨损微动磨损扭动微动力学行为数值模拟　出处：《西南交通大学》2013年博士论文　论文类型：学位论文

【摘要】：扭动微动作为一种基本相对运动和变形方式,大量存在于实际工况中,如交通工具中大量存在的球窝配合件及旋转紧固件、轮轴配合、人体关节、及各种人工关节等。其产生的磨损损伤会引发机械零部件服役安全及人体生命健康问题。但扭动微动研究起步较晚,报道较少,解析解存在一定局限性。西南交通大学摩擦学研究所开展的系统试验研究,主要在二类微动图基础上,建立了扭动微动磨损的运行和损伤机理,但扭动微动的力学行为和机理却有待分析与研究。同时,减缓微动损伤措施的研究主要集中于切向微动,表面工程技术在抗扭动微动损伤中的应用研究极为少见。因此开展扭动微动磨损和防护的力学行为分析,不仅可以深化扭动微动磨损损伤机理、丰富微动摩擦学理论,而且对实际应用中抗扭动微动磨损失效具有重要的工程指导意义。本研究基于接触问题有限元方法对扭动微动开展数值分析,研究关键微动参数对接触表面及次表面的应力应变分布的影响。从力学角度分析扭动微动磨损损伤特性,并将力学行为和实验现象进行对比分析；并利用ABAQUS用户子程序Fric引入接触表面随时间和空间各项同性变化的摩擦系数,对扭动微动磨损进行数值模拟。在摩擦扭矩曲线和试验结果较好吻合基础上,进一步分析扭动微动力学行为；同时开展MoS2涂层扭动微动有限元分析,通过与基体力学行为的比较,探讨固体润滑涂层在抗扭动微动磨损中应用的可行性。获得的主要结论如下： (1)扭动微动有限元分析结果显示：不同运行区域扭矩曲线形状与试验结果较好吻合,说明有限元分析中接触表面的变形行为和摩擦行为与实际基本相符。在有限元分析中,需依据T-θ曲线形状结合接触状态转变特征分析来划分运行区域。椭圆型T-θ曲线,并且接触状态云图中粘着区随循环周次增加有减小趋势,表明微动运行于混合区。 (2)数值模拟结果的三种微动运行区域下摩擦扭矩—角位移幅值曲线与试验结果无论在形状还是数值上均较好吻合,说明所采用摩擦系数模型能够模拟扭动微动接触界面摩擦系数演化及变形行为,在扭动微动磨损力学机理分析中考虑摩擦系数的动态变化非常有必要。在此基础上,扭动微动的力学行为分析和损伤机理揭示更加可靠。 (3)表面塑性变形和摩擦剪力对表面磨损起主控作用。三种扭动微动运行区域塑性应变和摩擦剪应力的分布和演化不同,相应的磨损损伤程度和演化也不同。 (4)结合SWT参数和关键平面方法,对混合滑移区接触副表面的裂纹萌生与扩展位置进行预测分析。结果表明：次表面应力应变分布状态决定了裂纹萌生与扩展,裂纹应在粘滑交界处和滑移区内接近接触边缘处萌生与扩展,预测结果与试验结果较好吻合。 (5)与LZ50钢相比,MoS2涂层的运行区域没有混合区,其滑移区向小角位移幅值和高法向载荷方向移动,说明通过微动运行区域的改变消除了混合区的损伤；MoS2涂层表面呈现的低摩擦使其与基体相比极易进入滑移区,表面相对运动幅度较大,但摩擦扭矩值却处于较低水平,表面摩擦剪力始终较小,故由摩擦磨损产生的表面损伤比基体材料轻微。
[Abstract]:Torsionalfretting as a basic relative motion and deformation mode, exists in the actual condition, such as the existence of a large number of vehicles with a ball and a rotating shaft with fasteners, body joints, and various artificial joints. The wear damage can cause mechanical spare parts service life safety and human health problems. But the torsional fretting of a late start, few reports, analytical solutions of some certain limitations. Experimental study of Tribology Research Institute of Southwest Jiao Tong University carried out, mainly in two kinds of fretting maps based on a micro operation and damage mechanism of torsional wear, mechanical behavior and mechanism of torsional fretting but remains to be studied. At the same time. Study on mitigation measures focused on the fretting damage of tangential fretting, surface engineering technology in the application of torsional fretting damage in extremely rare. Therefore the development of micro twist The analysis of mechanical behavior of dynamic wear and protection can not only deepen the torsional fretting wear damage mechanism, but also enrich the fretting tribology theory. It also has important engineering guiding significance for the practical application of torsional fretting wear failure.
In this study, the finite element method of torsional fretting contact problems based on the development of numerical analysis, the key parameters of fretting contact surface and sub surface stress and strain distribution effect. From the point of view of mechanics analysis of torsional fretting wear damage characteristics, and contrasts the mechanical behavior and phenomena; the friction coefficient and the ABAQUS user subroutine Fric change time and space into isotropic contact surface, numerical simulation of torsional fretting wear. In good agreement with the curves of friction torque and the test results on the basis of further analysis of torsional fretting mechanical behavior; at the same time to carry out MoS2 coating torsionalfretting finite element analysis, by comparing with the mechanical behavior of the matrix, to investigate the feasibility of solid lubrication coatings on resisting torsional fretting wear in the application. The main results are as follows:
(1) torsionalfretting finite element analysis results of different operation area of torque curve shape and test agree well, indicating the contact deformation and friction behavior of the surface are basically consistent with the practice of finite element analysis. The finite element analysis, according to the T- curve of contact node theta state transition characteristics to divide operation area elliptic curve T-. Theta, and contact state image sticking zone with cycles decreases with increasing trend, showed that the fretting running on the hybrid zone.
(2) three fretting region of numerical simulation results of the friction torque and angular displacement amplitude curves and experimental results in terms of shape or values are in good agreement, which show that the model can simulate the torsional fretting friction coefficient of contact friction coefficient evolution and deformation behavior, the torsional fretting wear mechanism is considered in the analysis of dynamic change the friction coefficient is very necessary. Based on the analysis of mechanical behavior and damage mechanism of torsional fretting reveals more reliable.
(3) surface plastic deformation and friction shear force play a major role in surface wear. The distribution and evolution of plastic strain and frictional shear stress in three kinds of fretting operation region are different, and the corresponding wear damage degree and evolution are also different.
(4) combined with the SWT parameters and the critical plane method, the crack on the surface of the hybrid slip zone contact initiation and propagation position were predicted and analyzed. The results show that the surface stress and strain distribution determines the initiation and propagation of crack, crack in the stick slip and slip zone near the junction of the inner edge of the contact initiation and propagation. The prediction results and the test results are in good agreement.
(5) compared with LZ50 steel, the operating range of MoS2 coating without mixing zone, the slip zone to the small angular displacement amplitude and normal load direction, the mixed zone damage is eliminated by the fretting regime change; the low friction surface of MoS2 coating showed the compared with the matrix easily enter the slip zone the surface, the relative motion greatly, but the friction torque value is at a low level, the surface friction shear was always small, so the friction and wear surface damage of the matrix material produced slightly.

【学位授予单位】：西南交通大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TH117

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