超精密加工机床空气静压主轴系统径向气膜刚度分子动力学模拟
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摘要
针对计算流体力学对超精密加工机床空气静压主轴系统进行动力学分析时的大跨尺度建模问题,该文基于分子动力学模拟基本原理和相似理论,利用LAMMPS开源软件和雷诺相似准则建立了超精密加工机床空气静压主轴系统的分子动力学微观模型。通过与文献算例比较验证了该模型的准确性,并进行了仿真分析。结果表明,在一定范围内,空气静压主轴径向气膜刚度随气膜厚度的增大而非线性减小,随主轴转速的增大而非线性增大,随进气压力的增大而非线性增大。
In view of the large-span scale problem of the computing model when dynamic analysis for the aerostatic spindle system of an ultra-precision machine tool is conducted by the computational fluid dynamics( CFD),based on the molecular dynamics simulation and similarity theory,the molecular dynamics microscopic model of the aerostatic spindle system for the ultra-precision machine is established by using an open source software LAMMPS and the Reynolds similarity criterion,and it is validated by the example of the reference. The results show that the radial gas film stiffness for the aerostatic spindle system decreases nonlinearly with the increase of the gas film thickness,increases nonlinearly with the increase of the spindle speed,and increases nonlinearly with increase of the inlet pressure in the certain range.
In view of the large-span scale problem of the computing model when dynamic analysis for the aerostatic spindle system of an ultra-precision machine tool is conducted by the computational fluid dynamics( CFD),based on the molecular dynamics simulation and similarity theory,the molecular dynamics microscopic model of the aerostatic spindle system for the ultra-precision machine is established by using an open source software LAMMPS and the Reynolds similarity criterion,and it is validated by the example of the reference. The results show that the radial gas film stiffness for the aerostatic spindle system decreases nonlinearly with the increase of the gas film thickness,increases nonlinearly with the increase of the spindle speed,and increases nonlinearly with increase of the inlet pressure in the certain range.
引文
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[3]熊万里,黄红武,张峻辉,等.高速精密电主轴动态热态特性的研究进展[J].振动工程学报,2004(17):61-64.Xiong Wanli,Huang Hongwu,Zhang Junhui,et al.Research progress of dynamic thermal characteristics of high speed precision motorized spindle[J].Journal of Vibration Engineering,2004(17):61-64.
[4]龙威,宗洪锋.节流器类型对空气静压导轨静特性的影响分析[J].机床与液压,2012,40(21):63-68.Long Wei,Zong Hongfeng.Analysis about influence of type on static characteristics of aerostatic guideway[J].Machine Tool&Hydraulics,2012,40(21):63-68.
[5]Su J C T,Lie K N.Rotation effects on hybrid air journal bearings[J].Tribology International,2003,36(10):717-726.
[6]Yu P,Chen X,Wang X.Frequency-dependent nonlinear dynamic stiffness of aerostatic bearings subjected to external perturbations[J].International Journal of Precision Engineering and Manufacturing,2015,16(8):1771-1777.
[7]郑小霞,叶聪杰,符杨.基于微分改进的EMD滚动轴承局部故障诊断[J].南京理工大学学报,2014,38(1):59-64.Zheng Xiaoxia,Ye Congjie,Fu Yang.Localized fault diagnosis of rolling bearing using differential improved EMD[J].Journal of Nanjing University of Science and Technology,2014,38(1):59-64.
[8]Memarian F,Fereidoon A,Khodaei S,et al.Molecular dynamic study of mechanical properties of single/double wall Si CNTs:Consideration temperature,diameter and interlayer distance[J].Vacuum,2017,139:93-100.
[9]文玉华,朱如曾,周富信,等.分子动力学模拟的主要技术[J].力学进展,2003,33(1):65-73.Wen Yuhua,Zhu Ruzeng,Zhou Fuxin,et al.The main techniques of molecular dynamics simulation[J].Advances in Mechanics,2003,33(1):65-73.
[10]刘予成,陈秀敏,李秋霞,等.氟磷酸钙真空碳热还原反应机理的分子动力学研究[J].真空科学与技术学报,2017(1):89-93.Liu Yucheng,Chen Xiumin,Li Qiuxia,et al.Molecular dynamics simulation of vacuum carbon thermal reduction of calcium fluoride phosphate[J].Chinese Journal of Vacuum Science and Technology,2017(1):89-93.
[11]Gao S,Cheng K,Chen S,et al.Computational design and analysis of aerostatic journal bearings with application to ultra-high speed spindles[J].Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science,2016,231(7):1989-1996.
[12]胡帼杰,董若宇,曹炳阳,等.简单流体非牛顿现象的分子动力学研究[J].工程热物理学报,2013,34(12):2309-2313.Hu Guojie,Dong Ruoyu,Cao Bingyang,et al.Non-Newtonian behaviors of simple fluids by molecular dynamics simulations[J].Journal of Engineering Thermophysics,2013,34(12):2309-2313.
[13]张玥.纳米轴承动压润滑的分子动力学模拟[D].南京:东南大学机械工程学院,2009.
[14]吴利杰,杨春娥,王为辉.空气静压径向轴承静态性能的有限元分析[J].机电工程,2015,32(9):1201-1205.Wu Lijie,Yang Chune,Wang Weihui.Finite element analysis on static characteristics of aerostatic radial bearing[J].Journal of Mechanical Engineering,2015,32(9):1201-1205.