Influence of percent alignment and shelling ratio on linear expansion of oriented strandboard: A model investigation

Oriented strandboard (OSB) is a versatile engineered material because the o rientation of the strands and the shelling ratio (a measure of weight perce ntage of the face layer) can be easily changed to modify its properties. Th is paper reports a model investigation on the influence of orientation leve l of the strands as measured by percent alignment (PA) and shelling ratio ( SR) on linear expansion (LE) of OSB. In general, reduction of LE in one dir ection is achieved at the expense of LE in the other direction. There is, h owever, an exception. The analysis showed that if PA is equal in both the f ace and core layers, increasing PA decreases LE in both directions at the s ame time if SR is around 0.5. This paper also discusses the LE ratio (LE-Pe rpendicular/LE-Parallel) in relation to PA and SR. The interdependence of P A in the face, PA in the core, and SR is graphically presented for the cont rol of LE ratio. The ramification of incorporating large amount of fines in the core of OSB, a popular practice in the industry, is also discussed.