Mots-clé
(Anglais)
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FRACTURE MECHANICS; WOOD; LATTICE MODEL; MISROSTRUCTURE; HETEROGENEITY
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Programme de recherche
(Anglais)
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COST-Action E35 - Fracture mechanics and micromechanics of wood and wood composites with regard to wood machining
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Description succincte
(Anglais)
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Wood is a highly heterogeneous material with several hierarchical levels of organisations. The multiplicity of wood cell interfaces and natural defects in wood cells play predominant role in wood fracturing. The main objective of this project is to investigate the relationship between wood microstructural features and its fracture behaviour through a morphological-based model, representing wood at cell level, coupled with experimental measurements. These measurments would permit us to characterise the microstructure of wood at cell level and determine the material parameters, the stiffness and strength, of wood components presented as a lattice.
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Autres indications
(Anglais)
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Full name of research-institution/enterprise: EPF Lausanne Département des matériaux Laboratoire des matériaux de construction
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Partenaires et organisations internationales
(Anglais)
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AT, CH, DE, DK, ES, FI, FR, GR, HR, IT, NO, PL, PT, RO, RS, SE, SI, SK, UK
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Résumé des résultats (Abstract)
(Anglais)
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To investigate the fracture behaviour of wood in cell level, the porosity and heterogeneities of its microstructure should be taken into account. For this purpose and to avoid the difficulties of considering these features of wood microstructure in a continuum-based fracture model, a mixed lattice-continuum model was developed. In this model, the volume where crack propagation was probable was introduced by defining a three-dimensional lattice of different beam elements, which represented the earlywood fibres, latewood fibres and their bonding medium. The other regions of the volume were considered as the continuum medium. The proposed model was used to investigate the mechanism of mode I fracture in a small notched wood specimen in RL orientation. The resulted pre-peak and softening curves and also the crack opening trajectory in both cross-section and longitudinal-section in model had a good agreement with the experimental evidences. Model showed the importance of considering the three-dimensional and distributed propagation of microcracks and main cracks in fracture stability. Also it was shown that in mode I fracture, RL orientation, the main crack mainly propagates in the earlywood ring.
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Références bases de données
(Anglais)
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Swiss Database: COST-DB of the State Secretariat for Education and Research Hallwylstrasse 4 CH-3003 Berne, Switzerland Tel. +41 31 322 74 82 Swiss Project-Number: C03.0031
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