Multiscale homogenization of wood transport properties: Diffusion coefficients for steady-state moisture transport

Abstract

This paper describes a multiscale homogenization model for macroscopic diffusion properties of wood. After a short introduction the physical background of steady-state diffusion processes in wood will be highlighted, resulting in a physically motivated macroscopic description of diffusion processes with only one diffusion equation and thus one diffusion tensor. This macroscopic diffusion tensor is derived by revisiting the morphological structure of wood in the framework of continuum micromechanics. The starting point is the cellular structure of wood; further homogenization steps include wood rays and the succession of annual rings. The quality of the model is assessed by a comparison of model predictions and measured values at different temperatures and moisture contents.

Keywords:

• Continuum micromechanics
• multiscale homogenization approach
• steady-state moisture diffusion

Acknowledgements

The authors gratefully acknowledge the financial support of the Austrian Research Promotion Agency (FFG, project no. 815234/12791) and the wood industry partnership “Building with wood” within CEI-Bois for funding the research work within the project “MechWood”. This work forms part of that project. The MechWood research partners are thanked for their co-operation and collaboration in this project.