Application of fiber undulation model to predict oriented strand composite elastic properties

The effects of strand undulation angles in wood-strand composites have often been ignored due to the virtual impossibility of experimental determination of their effects on composite material properties, and the diffi culty in modeling localized deviations in angle along the path of a strand. The fi ber undulation model (FUM), that has been previously verifi ed, was applied in this study to predict the elastic constants of laboratory-manufactured oriented strand panels. A stochastic approach was incorporated where a series rule of mixtures with probability density functions of angle distributions was utilized in the model to transform the elastic constants in the constitutive matrix of the material for in- and out-of-plane strand deviations. Based on a theoretical approach, a reduction in Ex due to strand undulations averaged about 7 percent over all confi gurations of test panels, indicating that localized out-of-plane strand deviations in commercially manufactured wood-strand composites should not signifi cantly affect longitudinal Young's modulus.