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Load Carrying Mechanisms in Wood at Different Observation Scales: A Combined Random-Periodic Multistep Homogenization Scheme

Published online by Cambridge University Press:  26 February 2011

Karin Hofstetter ,
Christian Hellmich  and
Josef Eberhardsteiner
Karin Hofstetter
Affiliation:
karin.hofstetter@tuwien.ac.at, Vienna University of Technology, Institute for Mechanics of Materials and Structures, Karlsplatz 13/202, Vienna (Wien), A-1040, Austria
Christian Hellmich
Affiliation:
christian.hellmich@tuwien.ac.at, Vienna University of Technology (TU Wien), Vienna (Wien), A-1040, Austria
Josef Eberhardsteiner
Affiliation:
josef.eberhardsteiner@tuwien.ac.at, Vienna University of Technology (TU Wien), Vienna (Wien), A-1040, Austria
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Abstract

Wood exhibits a highly diversified microstructure. It appears as a solid-type composite material at a length scale of some micrometers, while it resembles an assembly of plate-like elements arranged in a honeycomb fashion at the length scale of some hundreds of micrometers. These structural features of wood result in different load carrying mechanisms at different observation scales and at different loading conditions. In this paper, we elucidate the main load carrying mechanisms by means of a micromechanical model for wood across different species, based on tissue-independent stiffness properties of cellulose, lignin, and water. The model comprises three homogenization steps, two based on continuum micromechanics and one on the unit cell method. The latter represents plate-like bending and shear of the cell walls, due to transverse shear loading and axial straining in the tangential direction Accurate representation of these deformation modes results in accurate (orthotropic) stiffness estimates, which deviate, on average, by less than 10 % from corresponding experimental results, across a variety of softwood species.

Keywords

biologicalmicrostructureelastic properties
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 975: Symposium DD – Mechanics of Biological and Bio-Inspired Materials , 2006 , 0975-DD07-09
Copyright
Copyright © Materials Research Society 2007

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References

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