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Licensed Unlicensed Requires Authentication Published by De Gruyter June 12, 2019

Relationships between wood properties of small clear specimens and structural-sized boards in three softwood species

  • Luka Krajnc ORCID logo , Niall Farrelly and Annette M. Harte ORCID logo EMAIL logo
From the journal Holzforschung


Research on the mechanical and physical properties of wood is commonly carried out on either small clear specimens or structural-sized boards. The first approach was more frequently utilized in the past, while the latter is more commonly used nowadays. However, there is very little information on how the two approaches relate with one another. This study aimed to quantify the relationships between the mechanical [modulus of elasticity (MOE) and bending strength] and physical properties (density) of both specimen sizes. A total of 1376 structural-sized boards from three different species (Douglas-fir, Norway spruce and Sitka spruce) were tested in bending, after which a small clear specimen was extracted from the undamaged portion of each board and re-tested in bending. Prior to destructive testing, all boards and clear specimens were evaluated using non-destructive technology. Poor-to-moderate relationships were found between all measured mechanical and physical properties of structural-sized timber and small clear specimens. In both specimen sizes, the properties correlated with one another within the same specimen size, as well as across the two sizes. The strength of correlations appears to be somewhat species dependent. Relatively good relationships were identified when comparing the mean tree values of the properties examined, suggesting either method can be used for a tree-level comparison. The non-destructive evaluation of specimens was shown to reflect the measured properties moderately well, with the relationships changing significantly depending on which measured property was being predicted.

  1. Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  2. Research funding: The first author would like to gratefully acknowledge the support from a Teagasc Walsh Fellowship (Grant Number: 201503) in conducting this work. This work was also supported by grant aid (Assessment of acoustic non-destructive methods) from the Forest Sector Development Division of the Department of Agriculture, Food and the Marine, Ireland. The authors would like to thank Coillte and the Irish Forestry Unit Trust for enabling access to the forests and providing the testing material. The use of GoldenEye-702 machine was kindly provided by the Murray Timber Group and the Viscan laser accelerometer was kindly provided by MiCROTEC. Martin Bacher from MiCROTEC helped with the scanning of the boards.

  3. Employment or leadership: None declared.

  4. Honorarium: None declared.


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Received: 2019-02-14
Accepted: 2019-04-23
Published Online: 2019-06-12
Published in Print: 2019-10-25

©2019 Walter de Gruyter GmbH, Berlin/Boston

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