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.
