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This paper reports on a study of the application of ultrasound waves in wood with the purpose of evaluating the latter's mechanical properties. The evaluation is based on the correlation between the speed of sound, modulus of elasticity and density. The speed of transmission is sensitive to the material's quality-determining factors; hence, this technique is an important industrial tool to improve the quality control of processes. The species used in the experimental procedure were "cupiúba" (Goupia glabra) and "jatobá" (Hymenaea sp). Tests were carried out to determine the properties of apparent density at 12% humidity content (ρap,12%), modulus of elasticity in static deflection (EM), and modulus of rupture (MOR). Ultrasound tests were also performed to find the stiffness matrix coefficient (CLL), for purposes of comparison with the static findings. The results and analyses lead us to conclude that the nondestructive ultrasound method can be employed to obtain reliable evaluations of the mechanical properties of dicotyledons.

This paper discusses the application of ultrasound waves on a Brazilian hardwood, Goupia glabra, to evaluate the sensitivity of the ultrasonic technique to the moisture content in wood. The velocity of ultrasonic wave is sensitive to the material's quality-determining factors; hence, this technique is an important industrial tool to improve the quality control of processes. The nature of the response of velocity of sound to changes in moisture content led us to conclude that moisture gradients during drying exert a dominating effect. The ultrasonic velocity was measured both parallel and perpendicular to the fibers of Goupia glabra during drying from green to 6% moisture content. The results of this study showed that velocity of ultrasonic waves is sensitive to changes in moisture content of lumber during drying. The velocity under dry conditions was always higher than the velocity under more humid conditions, in both directions of propagation

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