Dynamic Study of Pocket-Orifice Compensated Air Bearing System

Pocket-orifice compensated air bearing (PCAB) systems have been potential for use in high-rotational speed, and high-precision machine tool extensively and applied for a variety of mechanical engineering application. However, under certain operating conditions, PCAB systems exhibit non-periodic or chaotic motion as the result of a nonlinear pressure distribution within the gas film, gas supplied imbalances, an inappropriate design, and so forth. So, in order to understand and suppress as the bearing system occurs non-periodic motions and under what kind of operating conditions, the dynamic response of the PCAB system has been analyzed by using two different methods, namely a perturbation method and a hybrid numerical scheme combining the finite difference method and the differential transformation method. The key performances and solutions under different physical models obtained by these two methods are compared and verified. The dynamic behavior of rotor center has been examined under different operating conditions by bifurcation diagram, Poincare maps, power spectra and Lyapunov exponents etc. The results reveals that the bearing number affects the orbits of the rotor which show chaotic behaviour in the interval of 16.41 <= Lambda <18.2. The results obtained in this study can be used as a basis for future PCAB system design and the prevention of instability.