In this study, researchers attempted to investigate the effects of drilling and hole widening on the dynamic response of wood using nondestructive methods. Clear and sound rectangular (2 2 36 cm R T L) bars were prepared from Beech timber (Fagus orientalis) and drilled in four steps with 3, 5, 8 and 10-mm diameters at central points in length on the tangential (LT) surface in the radial (LR) direction. To evaluate the longitudinal modulus of elasticity, the free-free bars before and after drilling procedure were brought to free flexural vibration test. To study the effects of stepwise hole widening, the dynamic evaluations were compared with two flexural vibrations parallel to LR and LT surfaces. The holes decreased the longitudinal modulus of elasticity values when the bars were vibrated in LR, while the values in LT remained significantly constant throughout the stepwise drilling. The differences due to longitudinal modulus of elasticity values comparing LR and LT free flexural vibrations were proposed as defect indicators. (Résumé d'auteur

Abstract• In this study, longitudinal specific modulus of elasticity along the grain (specific MOE L = MOE L /ρ) as well as radial and tangential shear moduli (G LR and G LT ) of Populus Deltoides wood were examined in free flexural vibration in a free-free bar method, where end-cracks produced manually in LT plane along and parallel to annual rings in four different sizes.• The effects of four different crack sizes (0, 6, 12, and 18 cm) on elastic parameters of the bars were examined for their vibration properties based on Timoshenko bar equations, in order to find a procedure to make a confident choice of a clear specimen among the cracked ones, considering three initial modes of vibration.• Based on research findings, a significant correlation existed between radial and tangential shear moduli of the clear bars as G LR was approximately 15 percents higher than G LT . After making the shortest crack sizes, however, this correlation entirely faded. Statistically for 6 cm crack, decreases in specific MOE L for measurement on the tangential impact were not significant though they were for longer cracks.• It was also revealed that in specimen under the study if longitudinal specific modulus of elasticity from both LR and LT flexural vibrations were almost equal and G LR was slightly larger than G LT , the user could be confident enough to consider the specimen without severe longitudinal cracks. Mots-clés :fissure / endommagement / élasticité / vibration libre / Populus deltoides Résumé -Les constantes élastiques du bois de peuplier fissuré aux extrémités.• Dans cette étude, le module d'élasticité longitudinal spécifique (MOEL/ρ) et les modules de cisaillement radial et tangentiel (G LR and G LT ) du bois de Populus deltoides ont été mesuré en vibration de flexion libre-libre pour quatre différentes longueurs de fissures initiées manuellement dans le plan LT qui est parallèle au fil du bois et tangentiel aux limites de cernes.• Les effets des quatre différentes tailles de fissures (0, 6, 12 et 18 cm) sur les constantes élastiques des barres ont été examinées pour leurs propriétés vibratoires sur la base des équations de Timoshenko, dans le but de trouver une procédure conduisant à un choix fiable d'un échantillon sans défauts parmi les échantillons fissurés, ceci en considérant les trois modes initiaux de vibration.• Les résultats obtenus montrent une corrélation significative entre les modules de cisaillement radial et tangentiel des barres sans défauts, G LR étant environ 15 pour cent plus élevé que G LT . Cependant après avoir réalisé les fissures les plus courtes cette corrélation n'existe plus. Pour une fissure de 6 cm, la décroissance du module longitudinal spécifique mesuré en tangentiel n'est pas significative alors que c'était le cas pour des fissures plus longues.• Pour nos échantillons, nous avons également montré que si les modules d'élasticité longitudinaux spécifiques sont presque identiques et G LR légèrement plus important que G LT , l'utilisateur peut exploiter en confiance les échantillons sans f...

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It is preferred to perform conformity assessment of wood-based panels on the whole panel without cutting it down to smaller pieces. The modulus of elasticity, a mechanical property of wood, was determined by longitudinal vibration testing with the full-size panel, and the results were compared with results of tests of prismatic beams. The Brancheriau's correction coefficient was used to compensate for errors from cross-sectional dimension variations and errors from Poisson's ratio. Longitudinal excitation of the panels along the length was shown to be successful in evaluating the modulus of elasticity. However, strong correlations obtained from plate and beam comparisons along the width of the panels are promising.

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In this study, the elastic properties of 23 specimens of oak timber (Quercus castaneifolia), including the longitudinal modulus of elasticity (MOE), acoustic coefficient (K), and acoustic converting efficiency (ACE) in free vibration using the free-free beam method with different planes of vibration, i.e. tangential (LT) and radial (LR), were studied. These elastic parameters were examined in both sound wood and finger jointed timbers with two different lengths of fingers (5-and 10-mm finger lengths) and individually glued with two different types of adhesives (isocyanate and polyvinyl acetate). Comparing the elastic properties of solid beams with finger jointed beams of oak wood in both (LT) and (LR) planes, 10-mm finger joints with polyvinyl acetate adhesive did not cause any serious change to the studied elastic properties of the beams, while shorter finger length (5 mm) with isocyanate adhesive severely changed the acoustic properties; therefore, beams having longer finger lengths may have enhanced acoustical properties.