359 木材の複屈折音弾性効果に及ぼす組織異方性の影響(OS2-3 異方性)(OS2 超音波と材料評価)  [in Japanese] 359 Influence of texture-anisotropy on the acoustoelastic birefringent effect of wood  [in Japanese]

Changes in shear wave velocity were measured by the sing-around method rotating the oscillation direction of the wave with respect to the orthotropic axis of wood. The velocity of the shear wave propagated through the stressed wood decreased suddenly when the oscillation direction coincided with the tangential direction of the wood. The polarization direction of shear wave coincided with the principal axes of wood, not with the direction of the principal stresses. This finding indicated that the polarization direction was much affected by the texture-induced anisotropy of wood. Based on the result, the bending and shear stress distributions in wood beam specimen were estimated by the acoustoelastic birefringent method. The stress values estimated agreed well with those obtained by the strain-gauge method and mechanical calculations.