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Type: Artigo de periódico
Title: Dispersion Of Ultrasonic Waves In Eucalyptus Lumber As A Function Of The Geometry Of Boards
Author: Bartholomeu A.
Goncalves R.
Bucur V.
Abstract: The aim of this article is to study the ultrasonic propagation phenomena in Eucalyptus lumber taking into consideration the dispersion of ultrasonic waves induced by the size of boards. Two types of waves were selected: surface waves and longitudinal waves of 45kHz frequency. The boards of 2m length in air dry condition were selected to have well defined transversal sections, related to three axes of wood, longitudinal (L), radial (R) and tangential (T). The velocity of propagation of surface waves in L direction decreased as a function of propagation distance (d), wavelength λ and the ratio d/λ < 5. For higher values the velocity was constant. The polarization plane of surface waves LR or LT induced differences from 3% to 20% on the measured value of surface velocity in L direction, in tangential boards. The velocity of propagation of bulk longitudinal waves was studied on the same boards, on which by successive cuttings the section was modified. If the length of the board is variable and the section is constant, then the velocity of propagation in longitudinal direction is very much influenced by the mode conversion of pure bulk waves into surface waves. Both surface waves and bulk waves can be used for the nondestructive testing of lumber.
Rights: fechado
Identifier DOI: 
Date Issue: 2003
Appears in Collections:Unicamp - Artigos e Outros Documentos

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