In-Plane Dimensional Stability of Three-Layer Oriented Strandboard

Jong N. Lee, Qinglin Wu

Abstract


In-plane swelling and bending properties of three-layer oriented strandboard (OSB) were investigated under the interactive influence of flake alignment level (FAL), flake weight ratio (FWR), resin content (RC), vertical density gradient, and moisture content (MC) levels. Mathematical models based on lamination theories were developed to predict effective modulus (EM), linear expansion (LE), and internal swelling stresses. The model's prediction was compared with actual experimental data.

It was shown that the relationship between LE and MC change for OSB was curvilinear with larger expansion rates at lower MC levels. FAL and FWR were two primary variables that significantly affected the magnitudes of LE, modulus of elasticity (MOE), and modulus of rupture (MOR). Increase in RC from 4% to 6% led to little change in all three properties.

The model predicted general trends of change in LE, EM, and swelling stresses as a function of FWR at the two alignment and two RC levels. The model's prediction in both EM and LE compared favorably with the experimental data. Prediction of the in-plane swelling stresses showed the effect of the panel MC change and directional dependency. The model provides an analytical tool for optimizing flake alignment level and panel flake weight ratio to achieve a proper balance between EM and LE for OSB manufacturing.


Keywords


Effective modulus;linear expansion;modeling;panel design;processing variables;structural panel

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