Luciane Paes Torquato had successfully defended her thesis!

15 January 2021

Luciane Paes Torquato, Ph.D. student in wood and bio-based materials engineering, successfully defended her thesis entitled “Modeling the dimensional stability and mechanical properties of black spruce wood” on December 15th! The CRMR is proud of you! Bravo!

MEMBERS OF THE JURY

President

Mr. André Desrochers FFGG

Examiners :

Mr. Alexis Achim, FFGG Research Director
Ms. Isabelle Duchesne, Co-Research Director NRCan-CFS
Roger E. Hernández, Co-Director of Research FFGG
Frédéric Mothe, external examiner INRA Grand-Est Nancy, Laboratoire SILVA
Alain Cloutier, FFGG examiner
Ahmed Koubaa, IRF-UQAT examiner

SUMMARY

Modeling the dimensional stability and mechanical properties of black spruce wood
The study of wood properties is very important to determine the potential use of wood in building structures and value-added products. A detailed knowledge of the variation patterns of wood properties within the tree is essential to optimize the use of this renewable resource and to develop high-performance products. The general objective of this research was to characterize and model the patterns of variation of the bending properties and dimensional stability of wood within the tree as a function of cambial age, height in the stem and width of the rings, taking into account the history of the stands. The study focused on black spruce (Picea mariana [Mill.] B.S.P.), which is of great commercial importance in Canada. Sixty trees in 12 stands located north and south of the North Shore, 30 trees in 6 stands in the Abitibi-Témiscamingue region and 42 trees in the Lac-Saint-Jean region were sampled. A statistical modeling approach was used to study the variation patterns of the studied properties. Regular and irregular stands, defined as a function of the time known since the last fire, were studied separately. The wood of the faster growing trees in the regular stands had superior mechanical properties and was less stable in terms of dimensions. Slower-growing trees from irregular stands could produce less dense final wood, which would tend to decrease the mechanical properties and increase the dimensional stability of the material. These properties would then be affected by the intra-circular variation patterns of wood density. The effect of stand type on the physico-mechanical properties of wood could also be due to a moderate presence of compression wood, which would be produced more in trees from marcottes or in trees subjected to larger and more complex mechanical stimuli. Moreover, predictive indices have shown that it is preferable to predict dimensional stability based on EOM measurements and cambial age rather than the opposite case, i.e. to estimate mechanical properties. These results could have practical implications for forest management and timber allocation decisions. The selection of forest stands to produce black spruce wood with high dimensional stability or high mechanical properties may be an interesting option emerging from this research.


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