tailieunhanh - Báo cáo khoa học: " Variation of moisture induced movements in Norway spruce (Picea abies)"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: Variation of moisture induced movements in Norway spruce (Picea abies). | 569 Ann. For. Sci. 58 2001 569-581 INRA EDP Sciences 2001 Original article Variation of moisture induced movements in Norway spruce Picea abies Charlotte Bengtsson Chalmers University of Technology Steel and Timber Structures 412 96 Goteborg Sweden Received 3 September 1999 accepted 3 January 2001 Abstract - This paper deals with the variability of moisture induced movements in Norway spruce wood. Totally 987 specimens from 12 well defined trees six from a fast-grown and six from a slow-grown stand were studied in detail. A large variation in moisture induced movements was found. The swelling coefficients in the longitudinal direction al varied between and in the tangential direction at between and and in the radial direction ar between and . Especially for al there was an individual variation with distance from the pith for each of the studied trees. For a t and a r there was a difference between the trees but no clear variation with distance from the pith. By excluding specimens containing knots and or compression wood the variability in swelling coefficients was decreased especially for al. The eigenfrequency in the longitudinal direction was the single best parameter measured in this study to predict swelling coefficients in all three directions. The variation in eigenfrequency explained 52 of the variations in al 67 of the variations in at and 52 of the variations in ar. Specimens from the fast-grown stand and specimens containing compression wood were less anisotropic than the other specimens. shrinkage swelling eigenfrequency raw material properties variability Résumé - Variation des mouvements induits par l humidité dans l Épicéa Picea abies . Ce papier traite de la variabilité des mou-vements induits par l humidité dans le bois d Epicéa. En tout 987 échantillons provenant de 12 arbres bien identifiés 6 d un site à crois-sance rapide et 6 d un site à croissance lente ont été étudiés en détail. Une variation importante des .

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