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.
Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
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.
Employment or leadership: None declared.
Honorarium: None declared.
American Society for Testing Materials (2014) ASTM D143-14: Standard Test Methods for Small Clear Specimens of Timber.Search in Google Scholar
Baar, J., Tippner, J., Rademacher, P. (2015) Prediction of mechanical properties – modulus of rupture and modulus of elasticity – of five tropical species by nondestructive methods. Maderas-Cienc. Tecnol. 17:239–252.10.4067/S0718-221X2015005000023Search in Google Scholar
Brancheriau, L., Bailleres, H., Guitard, D. (2002) Comparison between modulus of elasticity values calculated using 3 and 4 point bending tests on wooden samples. Wood Sci. Technol. 36:367–383.10.1007/s00226-002-0147-3Search in Google Scholar
British Standards Institution. Methods of Testing Small Clear Specimens of Timber. British Standards Institution, London, 1957.Search in Google Scholar
Butler, M.A., Dahlen, J., Antony, F., Kane, M., Eberhardt, T.L., Jin, H., Love-Myers, K., McTague, J.P. (2016) Relationships between loblolly pine small clear specimens and dimension lumber tested in static bending. Wood Fiber Sci. 48:81–95.Search in Google Scholar
CEN (2002) EN 13183-1:2002 – moisture content of a piece of sawn timber – part 1: determination of oven dry method. Comité Européen de Normalisation, Brussels, Belgium.Search in Google Scholar
CEN (2010) EN 384:2016 – structural timber – determination of characteristic values of mechanical properties and density. Comité Européen de Normalisation, Brussels, Belgium.Search in Google Scholar
CEN (2012) EN 408:2010+A1:2012 – timber structures – structural timber and glued laminated timber – determination of some physical and mechanical properties. Comité Européen de Normalisation, Brussels, Belgium.Search in Google Scholar
CEN (2016) EN 338:2016 – structural timber – strength classes. Comité Européen de Normalisation, Brussels, Belgium.Search in Google Scholar
Chan, J.M., Walker, J.C., Raymond, C.A. (2011) Effects of moisture content and temperature on acoustic velocity and dynamic MOE of radiata pine sapwood boards. Wood Sci. Technol. 45:609–626.10.1007/s00226-010-0350-6Search in Google Scholar
Divos, F., Tanaka, T. (2005) Relation between static and dynamic modulus of elasticity of wood. Acta Silv. Lign. Hung. 1:105–110.Search in Google Scholar
Gil-Moreno, D. Potential of Noble Fir, Norway Spruce, Western Red Cedar and Western Hemlock Grown for Timber Production in Great Britain. Ph.D., Edinburgh Napier University, Edinburgh, UK, 2018.10.1080/20426445.2018.1546283Search in Google Scholar
Grottal, A.T., Leichti, R.J., Gartner, B.L., Johnson, G.R. (2005) Effect of growth ring orientation and placement of earlywood and latewood on MOE and MOR of very-small clear Douglas fir beams. Wood Fiber Sci. 37:207–212.Search in Google Scholar
Haines, D.W., Leban, J.M., Herbe, C. (1996) Determination of Young’s modulus for spruce, fir and isotropic materials by the resonance flexure method with comparisons to static flexure and other dynamic methods. Wood Sci. Technol. 30:253–263.10.1007/BF00229348Search in Google Scholar
Hein, P.R.G., Brancheriau, L. (2018) Comparison between three-point and four-point flexural tests to determine wood strength of Eucalyptus specimens. Maderas Cienc. Tecnol. 20:333–342.10.4067/S0718-221X2018005003401Search in Google Scholar
Høibø, O., Vestøl, G.I., Fischer, C., Fjeld, L., Øvrum, A. (2014) Bending properties and strength grading of Norway spruce: variation within and between stands. Can. J. For. Res. 44:128–135.10.1139/cjfr-2013-0187Search in Google Scholar
International Organization for Standardization (2014) ISO 13061-4:2014: physical and mechanical properties of wood – test methods for small clear wood specimens: determination of modulus of elasticity in static bending.Search in Google Scholar
Lavers, G.M. (2002) The strength properties of timber.Department of the Environment, Building Research Establishment, H.M.S.O., London.Search in Google Scholar
Krajnc, L., Farrelly, N., Harte, A.M. (2019a) The effect of thinning on mechanical properties of Douglas fir, Norway spruce, and Sitka spruce. Ann. For. Sci. 76:12.10.1007/s13595-018-0787-6Search in Google Scholar
Krajnc, L., Farrelly, N., Harte, A.M. (2019b) The influence of crown and stem characteristics on timber quality in softwoods. For. Ecol. Manag. 435:8–17.10.1016/j.foreco.2018.12.043Search in Google Scholar
Madsen, B. (1992) Structural behaviour of timber. Timber Engineering Ltd., North Vancouver, British Columbia, Canada.Search in Google Scholar
McLean, J.P., Evans, R., Moore, J.R. (2010) Predicting the longitudinal modulus of elasticity of Sitka spruce from cellulose orientation and abundance. Holzforschung 64:495–500.10.1515/hf.2010.084Search in Google Scholar
Moore, J., Achim, A., Lyon, A., Mochan, S., Gardiner, B. (2009) Effects of early re-spacing on the physical and mechanical properties of Sitka spruce structural timber. For. Ecol. Manag. 258:1174–1180.10.1016/j.foreco.2009.06.009Search in Google Scholar
Nocetti, M., Brunetti, M., Bacher, M. (2015) Effect of moisture content on the flexural properties and dynamic modulus of elasticity of dimension chestnut timber. Eur. J. Wood Wood Prod. 73:51–60.10.1007/s00107-014-0861-1Search in Google Scholar
R Core Team (2018) R: a language and environment for statistical computing. Vienna, Austria.Search in Google Scholar
Raymond, C.A., Joe, B., Evans, R., Dickson, R.L. (2007) Relationship between timber grade, static and dynamic modulus of elasticity, and Silviscan properties for Pinus radiata in New South Wales. New Zeal. J. For. Sci. 37:186–196.Search in Google Scholar
Simic, K., Gendvilas, V., O’Reilly, C., Harte, A.M. (2019) Predicting structural timber grade-determining properties using acoustic and density measurements on young Sitka spruce trees and logs. Holzforschung 73:139–149.10.1515/hf-2018-0073Search in Google Scholar
Sorn, S., Bajramovic, R., Hadziabdic, V. (2011) Examination of proper span/depth ratio range in measuring the bending strength of wood based on the elementary bending theory. In: 15th International Research/Expert Conference ‘Trends in the Development of Machinery and Associated Technology’, TMT 2011, Prague, Czech Republic.Search in Google Scholar
Teder, M., Pilt, K., Miljan, M., Pallav, V., Miljan, J. (2012) Investigation of the physical-mechanical properties of timber using ultrasound examination. J. Civil Eng. Manage. 18:795–801.10.3846/13923730.2012.736233Search in Google Scholar
Unterwieser, H., Schickhofer, G. (2011) Influence of moisture content of wood on sound velocity and dynamic MOE of natural frequency- and ultrasonic runtime measurement. Eur. J. Wood Wood Prod. 69:171–181.10.1007/s00107-010-0417-ySearch in Google Scholar
Verkasalo, E., Leban, J.M. (2002) MOE and MOR in static bending of small clear specimens of Scots pine, Norway spruce and European fir from Finland and France and their prediction for the comparison of wood quality. Pap. Puu-Pap. Tim. 84:332–340.Search in Google Scholar
Vikram, V., Cherry, M.L., Briggs, D., Cress, D.W., Evans, R., Howe,G.T. (2011) Stiffness of Douglas-fir lumber: effects of wood properties and genetics. Can. J. For. Res. 41:1160–1173.10.1139/x11-039Search in Google Scholar
Yang, B.Z. (2015) Comparison of nondestructive testing methods for evaluating no. 2 southern pine lumber: part A, modulus of elasticity. Wood Fiber Sci. 47:10.Search in Google Scholar
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