THE CHANGE IN THE POROSITY OF A POROUS MATERIAL AT COMPRESSING

Abstract

The formulas for determining porosity based on the theory of plastic flow of porous materials for a sample with a circular cross-section are determined. The relationship between the theory of flow and the deformation theory of plasticity of porous materials is studied on the samples with a circular cross-section. Formulas of the theories of plastic flow and deformation were applied to determine porosity. Using a mathematical software package, porosity values were calculated at various points of the cross-section of the cyllindrical porous sample.

Based on the obtained values, graphs of porosity variation are constructed, calculated using the approximate and exact theories of plastic flow of porous materials, the deformation theory of plasticity, as well as the averaged values of these three theories.

In addition to the theoretical analysis, experimental investigations are conducted on cylindrical samples. Based on the data obtained from the experiments, graphs illustrating the variation of porosity in the samples at different levels of deformation are constructed. Using the constructed graphs, mathematical equations describing the variation of porosity along the radius of cylindrical specimens are obtained, providing a coefficient of determination

. These equations enable the determination of the material’s porosity at any point of the sample without the need for lengthy and costly experiments.