A collage of a tree and some other images; see the explanation below

Project: CT scanning and the influence of knots in structural timber

This project aimed to conduct a comprehensive analysis of wood material at a micro-scale level, using computer tomography. Specifically, it focused on investigating the three-dimensional fiber orientation near knots. The project provided new insights into the intricate fiber orientation around knots in Norway spruce, and enhances our understanding of the mechanical attachment of branches in living trees and engineering properties such as the stiffness and strength of sawn timber.

Illustration: Left – a Norway spruce tree is selected for research.
Middle – a piece of wood containing a knot, extending from pith to bark, along with an image obtained from CT scanning of the specimen.
Right – detected 3D fiber orientation in the vicinity of the knot.

Project information

Project manager
Anders Olsson
Other project members
Thomas Bader, Linnaeus University; Thomas Seifert, Stellenbosch University, South Africa
Participating organizations
Linnaeus University; Stellenbosch University, South Africa
1 Jan 2018–31 Dec 2020
Building Technology (Department of Building Technology, Faculty of Technology)

More about the project

The long-term goal of this project was to contribute to the development of future methods for efficient grading of structural timber and lamellas for engineered wood products. To achieve this, we needed to conduct basic studies on the properties of wood material near knots, as knots play a critical role in determining timber properties. The project utilized X-ray computer tomography (CT scanning), similar to the technology used in medical imaging to create three-dimensional images of human organs and tumors.

Within this project, we closely investigated the geometry of knots within the timber, as well as density variations and fiber orientation in the wood material surrounding the knots. Additionally, we will translate this new knowledge, obtained from CT scans, into mathematical descriptions of density variations and fiber directions. These models will enhance our ability to accurately determine crucial mechanical properties of the wood material at a local level.

The project was part of the research in the Wood Building Technology research group.

Project results

Project results are published in the article Fibre directions at a branch-stem junction in Norway spruce: a microscale investigation using X-ray computed tomography.