膜基体系微观接触力学特性研究

发布时间：2018-11-15 14:01

【摘要】：随着表面改性技术和材料技术的发展,Ti C、Ti N、DLC等膜层和表面离子注入、表面二重硬化等强化层已经在滚动轴承和齿轮等典型摩擦副中广泛应用,尤其是长期工作在高速、重载和高温苛刻工况条件下或者面临短时断油特殊工况条件下的摩擦副。在面向工况的膜基体系设计和开发过程中以经验知识和试验为基础的试错法具有较大的盲目性和随机性,目前膜层及表面强化层的摩擦学应用尚缺乏公认的设计准则。为了研究获得接触副表面膜层和接触表面微观形貌对摩擦副接触特性的影响规律,以便为膜层的应用设计提供分析方法和理论指导,首先提出了一种基于随机交换系统的粗糙表面数值模拟新方法,模拟生成随机粗糙表面为接触模型提供表面数据,然后基于半解析法建立了均质膜膜基体系弹性点接触模型,梯度膜膜基体系弹性点接触模型以及考虑热分配的均质膜膜基体系热弹性点接触模型,并基于这些模型研究了膜层和接触表面微观形貌对接触特性的影响。结合极坐标法和Johnson转换系统,提出了一种基于随机交换系统的粗糙表面模拟新方法。通过采用迭代算法,模拟得到的粗糙表面的统计参数与指定的统计参数之间的偏差得到有效控制,而且克服了现有方法自相函数的拟合程度随自相关长度的增大而变差的不足,从而提高了模拟精度。对真实工程表面的模拟表明本文提出的模拟方法也可用于指数函数以外的自相关函数的粗糙表面模拟,扩大了应用范围。由Papkovich-Neuber势函数获得了均质膜膜基体系在表面机械载荷作用下弹性场的频域解,并采用基于快速傅里叶变换的影响因子矩阵转换算法转换获得与表面法向压力和切向力相关的位移与应力的影响因子矩阵,从而建立了球体与均质膜膜基体系的三维弹性点接触模型,并通过与赫兹接触理论的解析解和有限元解的对比验证了模型的有效性。基于此弹性接触模型研究获得了膜层弹性膜量、厚度及接触表面粗糙形貌对接触压力和次表层接触应力分布的影响规律。通过引入傅里叶积分变换进一步推导了指数型梯度膜膜基体系在表面机械载荷作用下弹性场的频域解,并采用影响因子矩阵转换算法转换获得了梯度膜膜基体系与表面压力和切向力相关的位移和应力的影响因子矩阵,从而将均质膜膜基体系的接触模型推广应用到梯度膜膜基体系的接触模型,并通过与均质膜膜基体系接触模型的解和有限元解的对比验证了模型的有效性。基于梯度膜膜基体系弹性点接触模型研究获得了梯度膜表面弹性模量和膜厚对接触压力和次表层接触应力的影响规律,并与均质膜的影响规律做了对比分析。最后本文还考虑了摩擦热对均质膜膜基体系点接触特性的影响。采用傅里叶积分变换推导了均质膜膜基体系在表面摩擦热源等作用下的温升及热弹性场的频域解,然后采用影响因子转换算法转换获得与表面热源相关的表面温升、热位移和热应力的影响因子矩阵,从而通过引入基于接触界面真实接触区温度连续的热分配模型进一步建立了考虑摩擦热分配的均质膜膜基体系三维热弹性点接触模型,并针对没有膜层的接触问题通过本模型的解与前人的研究结果进行对比验证了模型的有效性。基于此热弹性接触模型研究获得了滑动速度、摩擦系数、膜层热传导系数、膜层热膨胀系数及接触表面粗糙形貌对接触压力、接触表面温升、膜基体系表面热流及次表层接触应力的影响规律。本文所建立的模型和方法将对苛刻复杂工况下长寿命摩擦副表面膜层和强化层设计、固液复合润滑状态分析、寿命预测和失效模式转换预测等提供理论依据。
[Abstract]:With the development of surface modification technology and material technology, the enhancement layers such as Ti C, Ti N, DLC and the like have been widely used in typical friction pairs such as rolling bearings and gears, especially for long-term work at high speed, Under the condition of heavy-load and high-temperature severe working conditions or under special working conditions of short-time oil-off oil, the friction pair is under the condition of special working conditions. In the process of design and development of the membrane-based system facing the working condition, the trial-and-error method based on the experience knowledge and the test is of great blindness and randomness, and the tribological application of the film layer and the surface strengthening layer is not well recognized as the design criterion. in ord to study that influence of the micro-morphology of the contact surface film and the contact surface on the contact property of the friction pair, in order to provide the analytical method and the theoretical guidance for the application design of the film layer, a new method of rough surface numerical simulation based on a random exchange system is proposed, in that method, a random rough surface is simulate to provide surface data for the contact model, and then the elastic point contact model of the film-based system of the uniform film, the elastic point contact model of the gradient film-based system and the thermal elastic point contact model of the uniform film-based system are established based on the semi-analytical method, The effects of the morphology of the film and the contact surface on the contact properties are studied based on these models. In this paper, a new method of rough surface simulation based on the random exchange system is proposed in combination with the polar coordinate method and the Johnson conversion system. By adopting the iterative algorithm, the deviation between the statistical parameters of the rough surface obtained by the simulation and the specified statistical parameter is effectively controlled, and the deficiency of the fitting degree of the self-phase function of the prior method with the increase of the autocorrelation length is overcome, and the simulation accuracy is improved. The simulation of the real engineering surface shows that the simulation method proposed in this paper can also be used for rough surface simulation of the autocorrelation function other than the exponential function, and the application range is expanded. The frequency domain solution of the elastic field under the action of the surface mechanical load is obtained by the Papkovich-Neuber potential function, and the influence factor matrix of the displacement and the stress related to the surface method to the pressure and the tangential force is obtained by using the influence factor matrix conversion algorithm based on the fast Fourier transform, The three-dimensional elastic point contact model of the sphere and the membrane-based system is established, and the validity of the model is verified by the comparison of the analytical solution with the Hertz contact theory and the finite element solution. Based on this elastic contact model, the influence of the film thickness, the thickness and the contact surface roughness on the contact pressure and the contact stress distribution of the subsurface layer was obtained. in that invention, the frequency domain solution of the elastic field of the exponential-type gradient film-based system under the action of surface mechanical load is further derived by introduce the Fourier integral transform, and the influence factor matrix of the displacement and the stress related to the surface pressure and the tangential force is obtained by using the influence factor matrix conversion algorithm, so that the contact model of the uniform film membrane-based system is applied to the contact model of the gradient membrane-based system, The validity of the model is verified by the comparison of the solution of the contact model with the membrane-based system and the finite element solution. The influence of the elastic modulus and the film thickness on the contact pressure and the contact stress of the subsurface layer was obtained based on the elastic point contact model of the gradient film-based system. In the end, the effect of the friction heat on the point contact properties of the membrane-based system was also considered. The frequency-domain solution of the temperature rise and the thermal elastic field of the membrane-based system of the uniform film under the action of the surface friction heat source is derived by the Fourier integral transformation, and then the influence factor matrix of the surface temperature rise, the thermal displacement and the thermal stress related to the surface heat source is obtained by using the influence factor conversion algorithm, so as to further establish a three-dimensional thermal elastic point contact model for the uniform film film-based system taking into account the friction heat distribution by introducing a thermal distribution model which is based on the real contact area temperature of the contact interface, and the validity of the model is verified by the comparison of the solution of the model and the previous research results for the contact problem without the film layer. The influence of the sliding speed, the friction coefficient, the heat transfer coefficient of the film layer, the coefficient of thermal expansion of the film layer and the roughness of the contact surface on the contact pressure, the temperature rise of the contact surface, the surface heat flow of the film-based system and the contact stress of the sub-surface layer were obtained based on the thermal elastic contact model. The model and method established in this paper will provide the theoretical basis for the long-life friction pair surface film layer and the reinforcement layer design, the solid-liquid composite lubrication state analysis, the life prediction and the failure mode conversion prediction under the severe and complicated working conditions.
【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TB383.2

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