Three-dimensional modeling of the structure formation and consolidation of wood composites

Abstract

Abstract A new three-dimensional (3D) computer simulation model is proposed to study structure development in wood composites, particularly strand or short fiber wood composites. The model takes into account the stochastic positioning and orientation of the strands within the mat. It also predicts the response of individual strands within the structure to the compressive and shear forces produced during mat consolidation. The model provides a complete description of mat structure in three dimensions, including spatial distribution of porosity, inter-strand contact, and density. Predictions for porosity obtained with the 3D model compare very well with those from an earlier two-dimensional analytical model. Mat structure is dictated by mat density in a two-step process: rapid removal of macrovoids before the mat density reaches the original wood density and asymptotic elimination of microvoids at higher mat densification. Other factors of importance include original wood density and strand dimensions, particularly strand thickness and width. Although known for its influence on mechanical properties, strand orientation seems to have little effect on mat porosity and strand contact.