稀薄效应下空气静压主轴动态特性分析及试验研究

中文摘要: 针对微尺度下空气静压主轴的动态特性问题，建立了体现稀薄效应的主轴有限元模型，对主轴的模态、谐响应进行了研究。首先，基于有限元法对主轴进行建模，轴承部分采用Combin14弹簧单元建模。接着，通过扰动法得出稀薄效应下以及传统情况下轴承的刚度、阻尼参数，将此参数替代主轴模态分析中采用的弹簧单元的刚度、阻尼参数，结合主轴实际工作状态，进而分析出两种情况下的主轴的模态结果。然后，对主轴进行谐响应分析，校核之前模态分析结果。最后，对主轴进行锤击模态试验，从而检验两种状态下的模态分析结果。实验结果表明：稀薄效应下分析所得主轴1阶固有频率值较试验测量值的误差只有3.6%左右，而传统情况下得出的1阶频率值的误差在15%左右，这对主轴系统以后的优化设计和精度控制方面具有一定的理论依据。
Abstract:For the problem of dynamic characteristic of aerostatic spindle,the finite element model considering the rarefaction effect was established.The modal and harmonic response of the spindle were analyzed.First,based on the finite element method to the spindle modeling,replacing the bearing with COMBIN 14 spring element,the stiffness of bearing and damp calculated under the rarefaction effects and traditional condition were served as the stiffness of spring,respectively.According to the actual working condition,the modal analysis in both cases were carried out.Then harmonic response analysis of spindle were also researched in the two situations to verify the results of modal analysis.Finally,Modal experiment of spindle by hammer exciting was performed to inspect the results of modal analysis and harmonic response.Experimental results indicated that the error of the first order natural frequency value of the spindle under the rarefaction effects is only 3.6% compared to the value of the test, while the error of the first order natural frequency value of the spindle under traditional scale is about 15% compared to the value of the test, which provides a certain basis for further optimization design and precision control of spindle system.