Experimental investigation of the limits of fluid squeeze out from an imbibed porous material

Abstract

Abstract The resistance to flow of a liquid squeezed out of a soft, porous structure subjected to compression generates a high load capacity and represents the mechanism on which the XPHD lubrication is based. The process is dependent on permeability which, in turn, depends on porosity, variable during compression. This study investigates experimentally the effect of compression on the porosity of open-cell polyurethane foams. An experimental device is used to compress a disc made of a porous material imbibed with glycerine and the volume of the remaining fluid is measured. Two reticulated foams with the same internal structure but with different initial porosities were selected for the study. The results are consistent and show a good correlation when compared with theoretical predictions. It is shown that the deformation of the solid fraction closes pores before squeezing out all the fluid. A residual porosity and a threshold strain when the pores are closed are put in evidence.