Analysis of shrinkage in wood

Abstract

Simple two dimensional shrinkage as it relates to wood is analysed starting from the classical definition of extension strain. Specific volumetric shrinkage is thereby expressed in terms of radial and tangential unit shrinkages and the moisture content at fibre saturation. Formulae are then derived which relate densities at different moisture contents and the basic density to moisture content at fibre saturation and the specific volumetric shrinkage. On the assumption that tangential and radial unit shrinkages are in the ratio 5:3, a formula is given which expresses radial and tangential unit shrinkages in terms of specific volumetric shrinkage, moisture content at fibre saturation and basic density.