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Structural Tali timber (Erythrophleum ivorense A. Chev., Erythrophleum suaveolens Brenan.): Assessment of strength and stiffness properties using visual and ultrasonic methods

Tali-Bauholz (Erythrophleum ivorense A. Chev., Erythrophleum suaveolens Brenan.): Bewertung der Festigkeits- und Steifigkeitseigenschaften anhand visueller und Ultraschallmethoden

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Abstract

The physical and mechanical properties (density, bending strength and stiffness) of 82 sawn pieces of Tali wood (Erythrophleum ivorense A. Chev., Erythrophleum suaveolens Brenan.) from Guinea and Cameroon were estimated using the EN 408 (2003) test standard. Timber pieces had a cross section of 80 mm×80 mm and 200 mm×250 mm and were visuallygraded according to British Standard BS 5756 (1997) in a single HS grade. The efficacy of this test was analyzed. The velocity of propagation of ultrasound waves had previously been measured by means of equipment specially designed for structural timber (Sylvatest Duo).

The results of visual grading according to BS 5756 (1997) show very low output with an excessive percentage of rejected pieces. Due to this, modifications are proposed to some of the specifications with the aim of reducing this percentage. Furthermore, visual grading does not facilitate to clearly separate the mechanical properties of HS grade and rejected pieces. The use of ultrasonic measurements shows good accuracy for the evaluation of stiffness properties, but not for strength. Visual grading makes it possible to reach a strength class of D50, while ultrasonic method could be used as an added parameter for grading.

Zusammenfassung

Die physikalischen und mechanischen Eigenschaften (Dichte, Biegefestigkeit und Steifigkeit) von 82 Tali-Kantholzstücken (Erythrophleum ivorense A. Chev., Erythrophleum suaveolens Brenan.) aus Guinea und Kamerun wurden nach der Prüfnorm EN 408 (2003) bestimmt. Die Holzstücke hatten einen Querschnitt von 80 mm×80 mm sowie 200 mm×250 mm und wurden nach der britischen Norm BS 5756 (1997) visuell in eine einzige HS-Klasse sortiert. Die Effizienz dieses Versuches wurde analysiert. Die Ausbreitungsgeschwindigkeit der Ultraschallwellen wurde vorher mittels einer speziell für Kantholz entworfenen Vorrichtung gemessen (Sylvatest Duo).

Die visuelle Sortierung nach BS 5756 (1997) ergab eine sehr geringe Ausbeute mit einem übermässig hohen Ausschussanteil. Um den Ausschussanteil zu reduzieren, wurden Veränderungen an der Spezifikation vorgeschlagen. Mit visueller Sortierung ist eine Trennung der mechanischen Eigenschaften der HS-Klasse und der Ausschussteile nicht eindeutig möglich. Mit Ultraschallmessungen können zwar die Steifigkeitseigenschaften präzise bestimmt werden, nicht aber die Festigkeitseigenschaften. Die Festigkeitsklasse D50 kann mit visueller Sortierung erreicht werden. Die Ultraschallmessung kann als zusätzlicher Sortierparameter eingesetzt werden.

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Authors and Affiliations

  1. Departamento de Construcción y Vías Rurales (Construction and Forest Roads Department), Escuela Técnica Superior de Ingenieros de Montes, Universidad Politécnica de Madrid, Ciudad Universitaria s/n., 28040, Madrid, Spain

    Francisco Arriaga, Guillermo Íñiguez & Miguel Esteban

  2. Laboratorio de Estructuras de Madera (Timber Structures Laboratory), Departamento de Productos Forestales (Forest Products Department), INIA (Instituto Nacional de Investigaciones Agrarias), Ctra. de la Coruña Km. 7,2, 28040, Madrid, Spain

    Juan Ignacio Fernández-Golfín

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  1. Francisco Arriaga
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  2. Guillermo Íñiguez
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  3. Miguel Esteban
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  4. Juan Ignacio Fernández-Golfín
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Correspondence to Francisco Arriaga.

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Arriaga, F., Íñiguez, G., Esteban, M. et al. Structural Tali timber (Erythrophleum ivorense A. Chev., Erythrophleum suaveolens Brenan.): Assessment of strength and stiffness properties using visual and ultrasonic methods. Holz Roh Werkst 64, 357–362 (2006). https://doi.org/10.1007/s00107-006-0100-5

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