The influence of rays on the transverse elastic anisotropy in green wood of deciduous trees

The green wood of twelve deciduous tree species was investigated regarding its radial and tangential moduli of elasticity measured in tension (E-R and E-T, respectively). In addition, the wood density and the volume fraction of rays were determined. A strong positive correlation was found between st ructural and stiffness properties, A simple two component model was derived for the relationship between the transverse elastic anisotropy factor (i.e ., E-R/E-T) of the green wood and the relative volume fraction of the axial and ray tissues. In the radial direction of the wood, the modulus of elast icity is influenced by the wood density and the volume fraction of rays; in tangential direction only the density seems to be important. However, the comparison between the elastic anisotropy and the volume fraction of rays i ndicates that the rays may have an indirect influence due to their shape.