Behaviour of sonogels under isotropic pressure

Abstract

The aim of this article is to present a method that simplifies the standard procedure to determine the yield point providing complementary information about changes in the behaviour of the materials under study. It is generally accepted that the yield point is determined by the inflection point of the curve of pressure versus apparent volume of the sample, P(V), from Hg porosimetry runs. Although compressible materials present an easily identifiable neat inflection point, in resilient materials, the inflection point is not easy to identify by simple visual inspection of the curve. A physical magnitude (K’) is introduced to characterise the evolution of the material's compliance under isotropic pressure. The physical meaning of K’ is the variation in the resistance to uniform compression with the pressure applied, helping to identify the yield point and the plastic mechanism beyond the yield point in a single run.