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Modulus of elasticity of Norway spruce saw logs vs. structural lumber grade

Zusammenhang zwischen dem E-Modul von Fichtenrundholz und den Sortierklassen von daraus hergestelltem Bauschnittholz

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Abstract

Structural lumber needs to be stiff, straight, and distortion free to comply with existing international standards. In Sweden there are set standards/certificates [?, ?] that are used to grade structural lumber. As pricing of structural lumber follows the structural lumber grade, there should be large economic benefits from using only saw logs that yield lumber with an acceptable structural grade. In recent years, acoustic technology has been considered as a potential technology for sorting saw logs into classes of modulus of elasticity. The current study, undertaken at a sawmill in central Sweden, explored the agreement between the dynamic modulus of elasticity of 828 Norway spruce (Picea abies) saw logs and structural lumber grade for ca. 2800 pieces of lumber sawn from these logs. The study showed a large span in modulus of elasticity (ca. 9–24 GPa) of logs. A fair agreement was observed between the modulus of elasticity of saw logs (representing two common diameter classes/sawing patterns) and the structural grade of the sawn lumber (according to Anon (1995), Anon (2000)). Thus, by excluding logs with low modulus of elasticity, sawmills could avoid production of low quality/low value structural lumber.

Zusammenfassung

Nach internationalen Normen muss Bauschnittholz eine gewisse Steifigkeit aufweisen und gerade sowie verformungsfrei sein. In Schweden werden Normen/Zertifikate [?, ?] zur Sortierung von Bauschnittholz verwendet. Da die Sortierklasse des Schnittholzes den Preis beeinflusst, ist zu erwarten, dass sich durch die ausschliessliche Verwendung von Stammabschnitten, die Schnittholz akzeptabler Güteklassen liefern, erhebliche wirtschaftliche Nutzen erzielen lassen. In den letzten Jahren wurden akustische Verfahren als mögliche Technologie zur Einteilung von Sägerundholz in E-Modul-Klassen erachtet. Die vorliegende Studie wurde in einem Sägewerk in Zentralschweden durchgeführt. Untersucht wurde die Übereinstimmung zwischen dem dynamischen E-Modul von 828 Fichtenholzabschnitten (Picea abies) und 2800 daraus eingeschnittenen Schnitthölzern. Dabei wies der E-Modul der Stammabschnitte eine grosse Streuweite auf (ca. 9–24 GPa). Der E-Modul von Sägerundholz (zwei herkömmliche Durchmesserklassen/Schnittbilder) stimmte mit den Sortierklassen des Schnittholzes (sortiert nach Anon (1995), Anon (2000)) ziemlich gut überein. Dementsprechend könnten Sägewerke eine Produktion von minderwertigem Schnittholz geringer Qualität vermeiden, wenn Stammabschnitte mit geringem E-Modul ausgeschlossen werden.

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Authors and Affiliations

  1. Dept. of Forest Products and Markets, Swedish University of Agricultural Sciences, Vallvägen 9A, 752 07, Uppsala, Sweden

    Jacob Edlund & Håkan Lindström

  2. Karbenning Sawmill, AB Karl Hedin Sågverk Karbenning, 738 92, Norberg, Sweden

    Fredrik Nilsson

  3. Dept. of Mathematics and Statistics, University of Canterbury, Private Bag 4800, Christchurch, New Zealand

    Marco Reale

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  1. Jacob Edlund
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  2. Håkan Lindström
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  3. Fredrik Nilsson
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  4. Marco Reale
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Correspondence to Håkan Lindström.

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Edlund, J., Lindström, H., Nilsson, F. et al. Modulus of elasticity of Norway spruce saw logs vs. structural lumber grade. Holz Roh Werkst 64, 273–279 (2006). https://doi.org/10.1007/s00107-005-0091-7

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