Abstract
The dynamic characteristics of aerostatic bearings are critical to the performances of ultra-precision manufacturing equipment. Dynamic characteristics have recently been recognized to be significant to the dynamic stiffness of aerostatic bearings, and related research has seldom been reported up till now. In this paper, numerical simulations and experiments are carried out to investigate the influence of perturbations on the dynamic stiffness of aerostatic bearings. The thrust bearings of an aerostatic bearing spindle are selected for simulations and experiments, while the journal bearing is used as frictionless guide way. Dynamic mesh method is adopted to simulate the variation of gas film, and numerical simulations are performed by using ANSYS-Fluent-software based on the perturbation theory. Perturbations are generated via voice coil motor under different conditions in experiments. Simulations and experimental results reveal that the dynamic stiffness is much more sensitive to the perturbation frequency rather than the nanoscale perturbation amplitude. For the same amplitude of displacement perturbations, the axial stiffness coefficient increases whereas the axial damping coefficient decreases with the increase of perturbation frequency. It indicates that the dynamic stiffness of aerostatic bearings can be significantly improved by using active control of the gas film to generate perturbations with high frequency.
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Abbreviations
- T :
-
absolute temperature
- ρ :
-
air density
- μ :
-
air viscosity
- p :
-
air pressure
- H :
-
bearing clearance
- P s :
-
supply air pressure
- R θ :
-
rotor radius
- r :
-
radial distance
- R :
-
air constant
- ω θ :
-
rotor angular speed
- ω p :
-
perturbation frequency
- p 0 :
-
bearing static air pressure
- p 1 :
-
bearing dynamic air pressure
- h 0 :
-
bearing static clearance
- h 1 :
-
bearing dynamic clearance
- θ :
-
angle of the radial direction
- V θ :
-
velocity in the radial direction
- U r :
-
velocity in the tangential direction
- p tr :
-
pressure of right thrust bearing
- p tl :
-
pressure of left thrust bearing
- h CT :
-
air clearance of aerostatic thrust bearing
- L T1 :
-
length of the aerostatic stator
- L T2 :
-
distance between right and left thrust bearings
- f P :
-
perturbation frequency
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Yu, P., Chen, X., Wang, X. et al. Frequency-dependent nonlinear dynamic stiffness of aerostatic bearings subjected to external perturbations. Int. J. Precis. Eng. Manuf. 16, 1771–1777 (2015). https://doi.org/10.1007/s12541-015-0232-9
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DOI: https://doi.org/10.1007/s12541-015-0232-9