Squeeze Films Between Rotating Porous Rubber Surface and Stationary Impermeable Rigid Surface

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Squeeze film phenomena between a rotating cylindrical porous rubber block with permeable surface and a stationary rigid plate with impermeable (nonporous) surface have been studied as a problem of viscoelastic hydrodynamic lubrication (VEHL). The rigid plate oscillates sinusoidally in the direction perpendicular to its surface and rotates about its axis. To estimate the porous surface deformation, the cylindrical porous rubber block is divided into, for simplicity, a set of concentric rings. Each ring is assumed to be deformed only axially and independently from the neighboring ones, and also the cross-sectional area is assumed not to change by the axial deformation. Then, the each ring is replaced with a spring-dashpot model made of three elements. The squeeze film pressures are obtained by simultaneously solving the equation of motion including the fluid inertia terms, the continuity equation, the Laplace equation including the centrifugal force caused by the rotation of the fluid wi … More thin the porous matrix, and the governing equation for the deformation of the porous rubber block. Experimental data on the squeeze film pressure, the squeeze film force and the frictional torque are measured with a cylindrical porous rubber block under the squeezing and rotating motion to verify the numerical analysis.The results are summarized as follows;(1) The peaks of the squeeze film pressure and force become large as the frequency and amplitude of sinusoidally oscillated motion increase and the time average film thickness decreases. On this point, the calculated results are in good agreement with the measured results.(2) For the sinusoidally oscillated motion and the rotational motion simultaneously applied to the porous rubber block, the variations of the squeeze film pressure and force with time have a tendency to shift to negative region as the rotational velocity increases. However, when the deformation of the porous rubber surface becomes noticeable, the quantitative effect of the rotational velocity on the shift of negative peaks of the squeeze film pressure and force is significantly small. These facts can be seen in both calculated and measured results.(3) The frictional torque increases in proportion to the rotational velocity, and for the squeezing and rotational motion simultaneously applied, the frictional torque varies with the frequency and amplitude of sinusoidal motion. On this point, the calculate results qualitatively agree with the measured results. Less