Abstract
This paper experimentally investigates the mechanical properties of rotary veneers peeled from small-diameter hardwood plantation logs, recovered from early to midrotation subtropical hardwood plantations. The study aims at providing essential probabilistic data needed to ultimately predict the capacity and reliability of veneer-based composites structural products [such as laminated veneer lumber (LVL) and plywood] from characteristics that can be measured in line during manufacturing. Two species planted for solid timber end-products (Gympie messmate, Eucalyptus cloeziana, and spotted gum, Corymbia citriodora) and one species traditionally grown for pulpwood (southern blue gum, Eucalyptus globulus) were studied. The compressive and tensile modulus of rupture (MOR) of the veneers, parallel to the grain and for veneer-based composite applications, were experimentally investigated. Results show that the compressive MOR for all species typically ranges from 30 to 50 MPa [for modulus of elasticity ] to 60 to 90 MPa (for ). The tensile MOR is typically lower than or in the range of the compressive MOR for MOE less than 12,000 MPa, while for larger MOE () tensile MOR greater than 140 MPa were observed. The total knot area ratio (tKAR) of the veneers is also analyzed and Weibull distributions were found to provide a good characterization of the statistical repartition of the tKAR value along the length of a veneer sheet. For each species, equations to best predict a veneer MOR from its measured MOE and tKAR value are derived and fit the experimental results with a coefficient of determination between 0.63 and 0.74. The variability of the MOR of each species was accurately modeled by Weibull distributions, with the distribution parameters determined based on the experimental data. Results shown that southern blue gum and Gympie messmate are the most and least sensitive species to size effects, respectively.
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Acknowledgments
The authors would like to thank the Australian Research Council for its financial support through project DE140100212. The support provided by the Queensland Department of Agriculture and Fisheries (DAF) through the provision of the unique Salisbury Research Facility is also acknowledged as critical to facilitate forest product research studies of this nature. The authors also express their gratitude to the Forest Product Innovation team at the Salisbury Research Facility for their invaluable help in preparing the samples and measuring their MOE. Mr. Alexander Mainey is thanked for performing part of the tests.
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Published In
Journal of Materials in Civil Engineering
Volume 29 • Issue 10 • October 2017
Copyright
©2017 American Society of Civil Engineers.
History
Received: Nov 23, 2016
Accepted: Apr 26, 2017
Published online: Jul 22, 2017
Published in print: Oct 1, 2017
Discussion open until: Dec 22, 2017
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