抄録
In order to examine the effect of the structural inhomogeneity of wood on its Young's modulus, an analytical model was proposed.
The model was constructed by considering the structural arrangement of earlywood and latewood cells in the cross section of softwoods, and also the fine structure of the cell wall (Fig. 1). The Young's moduli of earlywood and latewood in the transverse direction were evaluated on the basis of Finite Element Solution for the repeating units of the model. Data on the orientation of the microfibrils and area percentage of the layers in the cell wall presented by Saeki for Japanese cypress (Hinokiwood) were adopted, and the elastic constants of the cell wall layers were determined by means of three methods shown in Table I. The results were compared with the experimental values used by Boutelje for the samples consisting of isolated tissue components made of Swedish pine-wood (Table II, III).
It was indicated that the agreement between the calculated and experimental values was fairly good in magnitude, and the elastic anisotropy in the radial and tangential directions was affected by the geometry such as shape and size of the cell rather than the fine structure of the cell wall.
