Modelling Log-End Cracks Due to Growth Stresses: Calculation of the Elastic Energy Release Rate
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D. Jullien
Summary
The occurrence of log-end cracks, due to the release of growth stress pre-existing in the standing tree, causes severe damage at the early stage of wood transformation. A mechanical model based on Griffith's theory for elastic-fragile materials has been developed to explain the observed patterns: a crack can only progress when the elastic energy release rate (G) exceeds the toughness (Gc) of the material for the given fracture mode and orientation. At each stage of the crack propagation, G was calculated using the finite-element method. The influence of various parameters related to the rigidity components, the initial growth stress field or the crack geometry has been investigated, based on a set of experimental data gathered on a population of Eucalyptus. In all cases the high G values just after crack initiation are followed by a marked decrease until the periphery has been reached. Their order of magnitude for a typical log is similar to Gc values measured independently on similar material, thus supporting the validity of the approach.
Copyright © 2003 by Walter de Gruyter GmbH & Co. KG
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Articles in the same Issue
- Topochemical Characterisation of Phenolic Extractives in Discoloured Beechwood (Fagus sylvatica L.)
- Detection and Species Identification of Wood-Decaying Fungi by Hybridization of Immobilized Sequence-Specific Oligonucleotide Probes with PCR-Amplified Fungal Ribosomal DNA Internal Transcribed Spacers
- Analysis of Protein Expression along the Normal to Tension Wood Gradient in Eucalyptus gunnii
- Phenolic and Lipophilic Extractives in Scots Pine Knots and Stemwood
- Chemical Characterisation of Wood of Roman Ships Brought to Light in the Recently Discovered Ancient Harbour of Pisa (Tuscany, Italy)
- Lignin Structures in Normal and Compression Wood. Evaluation by Thioacidolysis Using Ethanethiol and Methanethiol
- Lignin-Carbohydrate Condensation Product Formation in a Biomimetic Model Pulp Bleaching System
- Viscoelastic Behaviour of Wood Fibres during the Hot Pressing of Medium Density Fibreboard
- Measuring Relative Fibre Length in Scots Pine by Non-Destructive Wood Sampling
- Modelling Log-End Cracks Due to Growth Stresses: Calculation of the Elastic Energy Release Rate
- Modeling Ovendry Softwood Resistivity Based on the Resistor Network Theory
- Comparison of the TL-Shear Strength of Normal and Compression Wood of European Larch
- A Theoretical Analysis of Timber Drying in Oscillating Climates
- Comparing the Effect of Chemical and Physical Properties on Complex Electrical Impedance of Scots Pine Wood
- Wood-Derived Porous Ceramics via Infiltration of SiO2-Sol and Carbothermal Reduction
- Manufacture of Fiberboard from Wood Fibers Activated with Fentons Reagent (H2O2/FeSO4)
