The Optimal Design Of Levitating Gas Squeeze Film Bearing

Gas squeeze film lubrication is a method which negative and positive pressure of gas occursalternately in the gap between two surfaces. And it is generated by the high frequency vibration in thenormal direction of two surfaces when driving the ultrasonic transducer which is made ofpiezoelectric ceramic material or magnetostrictive material or others ways. The negative and positiveasymmetric pressure results in the load carrying capacity of gas squeeze film. Comparing with theaero-static and aero-dynamic lubrication, gas squeeze film’s structure is simpler, and can workwithout externally pressurized air. Because of the extensive application prospects in precisionengineering and micro-machining, it is significant to study the gas squeeze film.In this paper, a gas lubrication model is built. Firstly, the governing equation of gas squeezefilm—Reynolds equation, which is a nonlinear of compressible gas—is derived from gas lubricationequation, and is solved by finite difference method numerically. At the same time, the influence ofoscillation amplitude and excitation frequency is studied. Because of the exchange of internal andexternal flow of squeeze film, the pressure changes all the time. When squeeze number is largeenough, the error of result is large with the traditional model, which the boundary pressure is equal toatmospheric pressure outside. And an appropriate boundary is given. Based on the theory of flexiblehinge, it designs a journal squeeze film bearing. In order to improving the load carrying capacity ofgas squeeze film, it is need to have a optimization design for the new journal gas squeeze film bearingwith flexure hinges by optimal design method. And lastly, an experiment is performed for verifyingthe floating height and load carrying capacity in different oscillation amplitudes.The studies of theoretical and experimental have shown that the influence of oscillation amplitudesis higher than excitation frequency. With the increasing of oscillation amplitudes, load carryingcapacity becomes large. While the larger the excitation frequency, the higher the load carryingcapacity at begin, when the excitation frequency is large sufficiently, the load carrying capacitybecomes stable. It is easy to solve the governing equation of squeeze film by the traditional boundarywhen the squeeze number is small. Otherwise, the remote boundary is better. After optimization, thedeformation of geometry of the journal gas squeeze film bearing is larger, and it can obtain a thickergas film. The theoretical results agree well with that of experiment.