Acoustic Propagation in Waterlogged Wood

While ultrasound is an established technique for the non-destructive evaluation of both cut timber and standing trees, it has not been applied to water-saturated wood. Hence, laboratory experiments were performed to discover the acoustic propagation mechanism in wood. If valid, the Biot model for acoustic waves in porous media should allow the prediction of laboratory measurements (taken at 300–1200 kHz). The results show that, for the best obtainable input parameters, the Biot theory models the observed anisotropy between the longitudinal, radial and tangential directions in wood. The model also predicts velocity dispersion of 1.4% between 300–1000 kHz in the longitudinal direction while that observed was 4.2%.