Abstract:

Theoretic analysis for elastic modulus of softwood was carried out in this paper. It was assumed that softwood cell comprises tracheid and wood ray, and the models of tracheid and wood ray cell were presented. The tracheid was modeled as a hollow cuboid with two wedged close ends and ray cell as a hollow close cuboid. Based on the two models and following the hypothesis of cell wall consisted of MP composite layer and S1, S2 and S3 composite layer, the calculative formula was derived for longitudinal elastic modulus of tracheid and wood ray cell by means of elastic bodies in series and in parallel. Meanwhile, the method was given to calculate the longitudinal elastic modulus of coniferous sample according to the elastic behavior and the arrangement of tracheids and wood ray cells within softwood. Work done in the paper reveals the relationship between the macroscopical elastic behavior of softwood and its anatomic structure as well as the micro elastic behavior of softwood cell. It can not only obtain much knowledge toward the mechanism of softwood elasticity but also be useful to estimation of the longitudinal elastic modulus of softwood.

Key words: Softwood, Tracheid, Wood ray, Elasticity of modulus