The influence of the microfibril angle on wood stiffness: a continuum micromechanics approach

  • Karin Hofstetter Vienna University of Technology
  • Christian Hellmich Vienna University of Technology
  • Josef Eberhardsteiner Vienna University of Technology

Abstract

Wood exhibits an intrinsic structural hierarchy. It is composed of wood cells, which are hollow tubes oriented in the stem direction. The cell wall is built up by stiff cellulose fibrils which are embedded in a soft polymer matrix. This structural hierarchy is considered in a four-step homogenization scheme, predicting the macroscopic elastic behavior of different wood species from tissue-specific chemical composition and microporosity, based on the elastic properties of nanoscaled universal building blocks. Special attention is paid to the fact that the fibrils are helically wound in the cell wall, at an angle of 00 - 300, generally denoted as microfibril angle. Consideration of this microfibril angle in the continuum micromechanics model for wood is mandatory for appropriate prediction of macroscopic stiffness properties, in particular of the longitudinal elastic modulus and the longitudinal shear modulus. The presented developments can be readily extended to the prediction of poroelastic properties, such as Biot and Skempton coefficients.

Keywords

wood, continuum micromechanics, anisotropic elasticity, wood cell wall, experimental validation,

References

[1] A. Bergander. Local variability in chemical and physical properties of spruce wood fibers. Doctoral Thesis, KTH Stockholm, 2001.
[2] A. Bergander, L. Salmen. Variations in transverse fibre wall properties: Relations between elastic properties and structure. Holzforschung, 54: 654- 660, 2000.
[3] A. Bergander, L. Salmen. Cell wall properties and their effect on the mechanical properties of fibers. Journal of Material Science, 37: 151-156, 2002.
[4] J. Bodig, B.A. Jayne. Mechanics of Wood and Wood Composites. Van Nostrand Reinhold, New York, USA, 1982.
[5] J.D. Boyd, R.C. Foster. Microfibrils in primary and secondary wall growth develop trellis configurations. Canadian Journal of Botany, 53(23): 2687- 2701 , 1975.
Published
Sep 26, 2022
How to Cite
HOFSTETTER, Karin; HELLMICH, Christian; EBERHARDSTEINER, Josef. The influence of the microfibril angle on wood stiffness: a continuum micromechanics approach. Computer Assisted Methods in Engineering and Science, [S.l.], v. 13, n. 4, p. 523-536, sep. 2022. ISSN 2956-5839. Available at: <https://cames.ippt.pan.pl/index.php/cames/article/view/877>. Date accessed: 23 dec. 2024.
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Articles