Analytical micromechanics equations for elastic and viscoelastic properties of strand-based composites

Using the principles of classical micromechanics, analytical equations are developed in this paper to estimate the effective orthotropic properties of a unit cell of strand-based composites according to their constituent phase properties and their microstructural features such as resin thickness, void content and strand geometrical characteristics. Although a special type of strand-based wood composite product, Parallel Strand Lumber, is considered here as an illustrative example, the methodology can be used for other wood composites consisting of high volume fraction of wood strands. The predictive accuracy of the derived analytical equations is investigated through comparisons with numerical results. Finally, applications of these equations in a linear viscoelastic analysis are discussed. The analytical micromechanics models developed here provide an efficient means of computing effective properties of a unit cell of strand-based composites. These models can then be used within a multi-scale modelling framework that has been developed previously to simulate the macroscopic behaviour of structures made of such materials.