【作者】 汪选国；

【导师】 严新平；

【作者基本信息】 武汉理工大学 ， 载运工具运用工程， 2009， 博士

【摘要】 摩擦学仿真是现代信息技术和计算机仿真技术并结合各种数学方法在摩擦学领域发展起来一门新的研究课题。由于实际摩擦学系统的复杂性和工况的不同,使传统模拟试验方法获得的结果往往只是定性的,不能很好地应用于摩擦学系统的设计和实际工程应用。有必要寻求新的方法和手段深入研究磨损的定量规律,否则就不可能期望在磨损的预防与控制上取得根本性突破。本课题研究的正是通过计算机技术和数学分析方法,选择销盘滑动磨损试验这类典型磨损试验系统为研究对象,进行滑动磨损试验的摩擦学仿真研究,以期提供一种新的磨损研究分析方法和相应的磨损仿真模型,实现基本的摩擦学接触问题和磨损问题的仿真。本文主要研究内容及结果如下:(1)选择机械零件常用材料45钢制作磨损试件,在MMW-1立式万能摩擦磨损试验机进行销盘滑动磨损试验。通过改变载荷、转速和热处理状态(硬度),获得了这些参数对磨损的影响规律。(2)在试验数据和理论分析基础上,建立了包含多个参数的磨损仿真模型;用试验数据确定了模型的参数,并用试验数据对模型进行了验证,结果表明,仿真模型基本能反映销盘干滑动磨损试验的输入输出关系。(3)在对摩擦副接触特性和接触应力计算理论分析基础上,推导了销盘接触应力理论计算模型。利用ANSYS软件分别对销盘接触副进行二维和三维的接触应力模拟分析。有限元模拟分析结果表明,接触界面压力分布是不均匀的,接触面中间接触压力小、边缘大,峰值达到外加载荷的2.786倍。销盘接触由静态变为动态时,接触应力场在形态和数值上都发生很大变化。三维和二维模型的计算结果类似,只是在数值有少量变化。分析结果表明,ANSYS有限元法可以用来对理想接触状态进行模拟,便于从直观上分析销盘的受力状态和它的摩擦磨损机理。(4)通过对销盘摩擦副试验工况条件的分析,建立起销盘试样摩擦表面温度及温度场分布的理论模型,对45钢销盘销试样摩擦表面温度及温度场分布进行模拟计算;并采用有限元法对摩擦表面温度场进行了仿真计算。计算结果表明,一维温度场稳态理论模型及二维差分稳态模型计算结果一致;二维和三维的有限元瞬态模型的计算结果进一步验证了一维稳态理论计算模型的可信性。有限元计算结果表明,销盘摩擦副在滑动磨损过程中,从开始滑动40s左右,温度场达到稳态,沿销轴线方向,稳态温升基本呈线性分布;二维和三维有限元模型计算的接触面最高温升基本一致;(5)针对销盘干滑动磨损率试验数据,分别进行了一元非线性回归模型、多元非线性回归模型和BP神经网络模型研究。通过对不同函数类型的一元非线性回归、多元非线性回归模型的分析,结果表明,指数回归模型的预测效果最好。通过比较不同隐层接点数的网络模型的预测结果分析,发现隐层接点数在7时,可获得较佳的预测结果,据此确定了网络模型的结构和具体参数。回归模型和BP网络模型都能够用来对销盘磨损率进行预测,但BP模型预测的精度更高。更多还原

【Abstract】 Tribological simulation was a new study problem developed from modern information technology and computer simulation technology in combination with a variety of mathematical methods in the field of tribology. Due to the complexity of actual tribological systems and different working conditions, the results obtained from traditional simulation test method were often qualitative only, and couldn’t be used to the designs of tribological system and practical engineering applications. There is a need to seek new ways and means of in-depth study of the wear quantitative law ,otherwise the fundamental breakthrough of the prevention and control of the wear could not be achieved. The tribological simulation research of the typical pin on disc sliding wear test system was carried by the adoption of computer technology and mathematical analysis methods, with a view to provide a new wear analysis method and the corresponding wear simulation model and to achieve simulation of the basic tribological contact problems and the wear problems.The content and results of this thesis were as follows:(1) The materials of 45 steel commonly used as mechanical parts was selected as wear specimens and the pin on disc sliding wear tests were carried on the MMW-1 vertical universal friction and wear test machine. By changing the load, speed and heat treatment state (hardness), the effect laws on wear of . these parameters were obtained(2) The wear simulation model including multiple parameters was established based on the experimental data and theoretical analysis. The parameters of the model were determined by the test data and to and the model was verified by the test data and the results showed that the simulation model could reflect the basic relationship between input and output of the pin on disc dry sliding wear test.(3) The contact stress theoretical calculating model of the pin on disc was deduced on the basis of the theoretical analysis of contact characteristics and contact stress calculation of the frictional couple. The two-dimensional and three-dimensional contact stress simulation analysis of the pin on disc contact couple were carried by the ANSYS software. The finite element simulation analysis results showed that the interface contact pressure distribution was uneven, contact pressure was small in the interspace of the contact interface and was big among the edge of the contact interface the small, the contact pressure peak reached 2.786 times of the load. The numerical value and conformation of the contact stress field arised great changes when the contact of Pin on disk was changed from static to dynamic state. The calculation results of three-dimensional and two-dimensional model were similar, only a small amount of change in value. The analysis results showed that ANSYS finite element method could be used to simulate the ideal contact state and it facilitated the analysis of stress state and friction and wear mechanism of the pin on disc from an intuitive view.(4) The theoretical modes of pin-on-disc specimens friction surface temperature and temperature field distribution were established through the test conditions analysis of the pin-on-disc friction couple, the friction surface temperature and temperature field distribution of 45 steel pin specimen was calculated by theoretical modes. Friction surface temperature fields were simulated also by finite element method. The calculating results of one-dimensional steady-state temperature field theoretical model of and two-dimensional steady-state differential model were same. The credibility of one-dimensional model of steady-state was further validated by the two-dimensional and three-dimensional transient finite element model results. The finite element analysis results showed that the friction temperature field of the pin on disc friction couple reached steady-state about 40s after start sliding in the sliding wear process, the steady-state temperature rise behaved basically linear distribution along the pin axis direction, the maximum temperature rise of the contact surfaces of the two-dimensional and three-dimensional finite element model are basically the same;(5) One dollar non-linear regression model, multivariate nonlinear regression model and BP neural network model were respectively studied for the pin on disk dry sliding wear rate data. The analysis results of different types of one dollar non-linear regression, multivariate nonlinear regression model showed that the forecast effects of the index regression model were the best. It was found that the forecast effects was the best when the number of points in hidden layer was seven by comparing forecast results the different number of points of hidden layer of the network model, accordingly the structure of the network model and specific parameters were determined. The regression model and BP network model all could be used to predict the pin on disk dry sliding wear rate, but the BP model forecast were more accurate.更多还原