Reverse Engineering the Tree

• Main Author: Davies, Nicholas Tuatahi
• Language: en
• Published: University of Canterbury. Forestry 2014
• Subjects: Timber; wood; trees; wind; growth stresses; FEM; typical radial pattern; MFA; density
• Online Access: http://hdl.handle.net/10092/9600

The aim of this thesis was to investigate the typical radial pattern of density and microfibril angle within Pinus radiata with respect to structural stability. In order to investigate changes in mechanical stability with different radial patterns, first experimental work was carried out in order to obtain elastic constants, Poisson ratios and limits of proportionality for green corewood and outerwood, these values, a discussion on their accuracy and the implications of the values are included along with a comparison to previous literature. These constants were used to parametrise a finite element model of a tree stem with different radial patterns, including patterns not observed in nature, wind loadings were applied to the stem and failure evaluated. It was found that patterns consisting of high density stiff wood and/or low density high flexibility wood could withstand the greatest wind speeds for a given stem and canopy, while high density flexible and low density stiff profiles generally performed poorly. The analysis was considered at ages 5, 10 and 15 years, each providing similar results. Why these profiles perform best, what errors need to be considered, and other evolutionary pressures which could narrow this list of profiles were discussed. The need for further research, and the directions for this research are suggested.