Finite element modelling of mechanical properties of geometrically characterized wood fibres

Background:
Wood fibres are frequently used in load-carrying applications, e.g. paperboard, composites, MDF boards, wood boards etc. It is not yet fully understood how the fibre geometry and fibre ultrastructure affects the stiffness of the fibres. At the Swedish University of Agricultural Science (SLU) in Uppsala, a research project within the Wood Ultrastructure Research Centre (WURC) has quantified the details of wood-fibre geometry with stereological and tomographic techniques. The aim is to use this structural information to predict the elastic properties of the anisotropic fibre. Most analytical models assume that the fibres are homogenous and cylindrical. The twist-extension coupling due to the micro-fibril angle is commonly neglected. How these simplifications limit the predictive capabilities of the models is not known. Such knowledge is useful in linking the material structure with engineering properties. Quantitative methods for materials design and development could then be devised.

Tasks:
The approach can be outlined as follows:
* Literature survey of tensile properties of single wood fibres
* Meshing of geometrical data of single wood fibres
* Incorporation of material properties, i.e. ultrastructural features, in a helical anistropic elastic configuration
* Finite-element modelling of longitudinal strain-strain and load-displacement behaviour. Software: ALGOR
* Comparison with experimental results found in the literature
* Writing of a M.Sc. thesis
* Oral presentations at the participating institutions
For a duration of 20 weeks, the project will be carried out at SLU in Uppsala. Meetings will be held on a monthly basis with the co-advisers at KTH and STFI-Packforsk. The goal is that the results should be of sufficient scientific quality to be used in a journal publication.

Prerequisites:
A strong background in finite element modelling and solid mechanics is advisable. An interest in biology and ¿green¿ materials is welcome. The candidate should preferably be a last-year student in a suitable M.Sc. programme in Engineering (¿civilingenjör¿), e.g. M, F, T, P or B.

Remuneration:
The project is funded by WURC (Wood Ultrastructure Research Centre) at SLU . After successful completion of the project, the M.Sc. candidate will receive a scholarship of SEK 30.000,00.