Prospects for within-tree variation of the acoustoelastic behaviors in Japanese cedar

Acoustoelastic behaviors of Japanese cedar were investigated between individual parts within the trunk (heartwood or sapwood) to clarify their within-tree variation. An ultrasonic longitudinal or shear wave was propagated through wood samples transversely to the applied stress direction. Changes in wave velocities due to the applied stress had a commonality between heartwood and sapwood. The magnitude and variation coefficients of acoustoelastic constants were larger for heartwood than for sapwood. These findings suggest that the acoustoelastic technique can be used for nondestructive stress measurements in every position within the trunk but that requires attention to the variations in acoustoelastic constants.