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EXPERTISE MECANIQUE DES SCIAGES PAR ANALYSES DES VIBRATIONS DANS LE DOMAINE ACOUSTIQUE

Abstract : In order to improve strength grading methods for building timbers, the aim of this work is to design and to test a system which allows to evaluate, in a non destructive manner and in a reliable way, the longitudinal modulus of elasticity and the bending strength of sawn timbers. This goal also includes the possibility to detect and quantify the presence of wood defects. Several steps are required to reach this aim. For a better understanding, these steps are described both in the logical and chronological way. The first step reviews the classic theories, used in modal analysis, clarifying their validity domain, and then establishes a new theoretical approach allowing to take into account and to characterize the presence of defects in timber beams. The second step allows to establish the link between the vibrations theory of plates and the one of beams. Consequently this step clarifies the validity domain of classic theories concerning vibration beams when the cross section dimensions are very different, which generally happens for the case of structural timbers. The third step allows to characterize, in a specific frequency range, by the way of a viscoelastic modeling in the dynamic behavior, all the waves transformations occurring during their propagation through the material. The fourth step deals with the problem of the detection of the singularities number and their location using a method derived from the impact – echo technique, analyzing the propagative waves reflexions at the bound between different mediums. The fifth and last step allows to evaluate the efficiency of all of the non destructive methods developed in the previous steps. Experimental tests are performed on several structural timber batches, in order to estimate their mechanical properties using specific statistic techniques.
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https://tel.archives-ouvertes.fr/tel-00008291
Contributor : Loïc Brancheriau <>
Submitted on : Friday, January 28, 2005 - 11:39:00 AM
Last modification on : Tuesday, October 20, 2020 - 3:10:21 AM
Long-term archiving on: : Friday, April 2, 2010 - 9:24:40 PM

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  • HAL Id : tel-00008291, version 1

Citation

Loic Brancheriau. EXPERTISE MECANIQUE DES SCIAGES PAR ANALYSES DES VIBRATIONS DANS LE DOMAINE ACOUSTIQUE. Mécanique [physics.med-ph]. Université de la Méditerranée - Aix-Marseille II, 2002. Français. ⟨tel-00008291⟩

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