892324 Wood physics

Type
Lecture and exercise
Semester hours
2
Lecturer (assistant)
Organisation
Offered in
Sommersemester 2023
Languages of instruction
Deutsch
Content

Ten lectures (each with two classes) will encompass theoretical, experimental and

numerical approaches and presentation of research findings in the field of moisture flow in wood. The lectures are aimed at graduate student level and they will be given in German.

The importance of environmental effects on the structural performance of wood has

been known for ages, moisture being the most pronounced degradative effect. In the living tree, wood contains large quantities of water. As green wood dries, most of the water is removed, and the level of humidity is determined by the wood Moisture Content (MC). The moisture remaining in wood tends to come to equilibrium with the relative humidity of the surrounding air, with the level of Equilibrium Moisture Content (EMC). Generally, most mechanical properties increase with the decrease in moisture content. Moisture moves by two main mechanisms in wood as a porous material: capillary action (liquid) and diffusion of bound water (vapour). On the macroscopic level Fick's law is found to be valid only at the low moisture contents, while for the higher humidity conditions wood exhibits anomalous Fickian behaviour. Diffusion coefficients can be determined in steady-state, or in transient state. Non-isothermal conditions are of importance where the moisture transfer is coupled with the heat transfer, the situation typical for the drying process of wood. During the changes in moisture content the shrinkage and swelling occurs, the phenomena of importance for dimensional stability, physical and mechanical properties.



Specifically, ten lectures will cover the following topics:



1. Introduction to moisture transfer in wood and basic definitions

2. Mechanisms of moisture flow

3. Diffusion and Fickian law

4. Diffusion parameters

5. Sorption-desorption phenomena

6. Coupling of heat and moisture transfer

7. Drying of wood

8. Moisture profiles

9. Shrinkage and swelling

10. Mechano-sorption effects in wood
Previous knowledge expected


Objective (expected results of study and acquired competences)

Students are expected to gain knowledge about the most relevant research findings in the area, and to learn the fundamentals of the moisture transfer in wood which would enable them to perform independent studies in this research field.
You can find more details like the schedule or information about exams on the course-page in BOKUonline.