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Anisotropy of three types of Iranian particleboards was estimated as the ratio of Young's moduli,
velocities of bulk waves (shear and longitudinal waves) and of acoustic invariant. The ultrasonic
through-transmission method was used to measure the ultrasonic velocities in principle syrnmetry axis.
Young s moduli were determined with the 4-point static bending test.
The results show that the velocity parallel to the production direction is higher than that in
perpendicular direction and is lowest through thickness because particles are directed in production
direction.
The structure of particleboard influences ultrasonic velocities, so the anisotropy behavior of
particleboard can be explained by the ratios of ultrasonic velocities. The used different methods for
description of anisotropy by ultrasonic parameters and static modulus of elasticity show to be in good
agreement.