Buffer Action of Fluid Films

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Hydraulic equipment is widely used for automation and high-performance operation of high-power machines and equipment. However, it is demanded to reduce the vibration and noise. The purpose of this study is to clarify the buffer action of fluid films and elastic deformation.In the first circular (1990), we carried out theoretical analysis. The theoretical model is the case that a cylinder impacts the surface of a cantilever through fluid films. We consider the changes of viscosity an compressibility of the fluid and the elastic deformation and deflection of the cantilever, independently. In this study, the efficiency of the buffer action is mainly evaluated by the changes of the coefficient of rebound. For the case where the impacting velocity is relatively small and the film thickness is comparatively large, the coefficient of rebound became small. Considering the deflection of the cantilever, the efficiency of the buffer action of films becomes to be clear with thin films.In the fina … More l circular (1991), we examined the buffer action experimentally. A cylinder (8.5 g, radius = 4.5 mm) and a sphere (8.35 g, radius = 6.35 mm) impacted the surface of the cantilever (Steel, length = 180 mm, width = 36 mm, thichness = 16 mm) and the infinite elastic body through the fluid film. By estimating the buffer action with the coefficient of rebound, the area-contacting is able to obtain larger buffer action than the point-contacting. It is clarified that the larger the fluid film thickness, the larger the buffer action, and as a whole the buffer action becomes larger by the cantilever. Furthermore, we compared with the theoretical (in the last circular) and experimental results for the case of the cylinders. They have good agreements for the coefficient of rebound qualitatively but do not quantitatively. For the case of the deflection of the cantilever, they have good agreements.In conclusion, it is possible to absorb the impacts by use of the fluid films and the elastic deformation, and estimate the effects by the theoretical analysis. Less