A Study on Squeeze Films Between Porous Rubber Surface and Rigid Surface: Analysis Based on the Viscoelastic Continuum Model

The squeeze-film effect between a porous rubber surface and a rigid surface has been investigated as a problem of viscoelastic hydrodynamic lubrication (VEHL). An axisymmetric continuum model is introduced to estimate the surface deformation of a cylindrical porous rubber block based on a three-element viscoelastic model. The coefficients in the viscoelastic constitutive equation are experimentally determined and then the deformation of the porous rubber block is calculated by the FEM technique. The approximate solutions for the fluid pressures in the squeeze film are obtained from the equation of motion, which includes both local and convective inertia terms, and the continuity equation, using the perturbation method. Experimental data on the squeeze-film pressures and forces are also obtained under the sinusoidal squeezing motion of a rigid plate facing a cylindrical porous rubber block. It is found that the difference between the VEHL solutions and the EHL (elastohydrodynamic lubrication) solutions becomes more marked for a higher frequency of squeeze oscillation due to the effect of viscoelasticity of the porous rubber. The VEHL solutions hence correspond better to the measured results and yield a smaller surface deformation of the porous rubber block than the EHL solutions as the frequency of squeeze oscillation increases. The results also show that the fluid inertia effect due to the flow in the squeeze film becomes noticeable for a higher frequency of the squeezing motion as the effect of viscoelasticity of the porous rubber.