WOOD MOISTURE · Experimental and computational modelling of mechano-sorptive fracture processes in wood
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2004-09-01 → 2006-07-31
- EU contribution
- €210,483
- Participants
- 1
- Scheme
- IIF
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Results in brief
Final Activity Report Summary - WOOD MOISTURE (Experimental and Computational Modelling of Mechano-Sorptive Fracture Processes in Wood)
Moisture transfer in wood was subjected to comprehensive experimental and numerical analysis. Fracture behaviour under varying humidity conditions was investigated on microstructural level using special microscopic techniques which allow for direct observation of fracture processes under load. Characterisation of fracture properties was evaluated through extensive experimental testing using wedge-splitting technique. Numerical simulations of interactions between the moisture and cracking were performed with finite element method and different fracture models .Especially challenging problems are resolved with implementation of digital image analysis to simulate exact microstructural features and with the analysis of anomalous mode of diffusion at higher moisture content levels. The results from both experimental and numerical investigation show that there exist a distinct influence of moisture on fracture behaviour and fracture properties of softwoods and hardwoods. More ductile behaviour at higher moisture content levels was evidenced, with increasing brittleness with a moisture content decrease. From the theoretical point of view significant achievement is novel treatment of green wood as a poroelastic media. Direct experimental evidence of fracture process zone at varying moisture content is also novelty, of special significance for physically based numerical models and realistic numerical simulations. Significant contributions were made also with simulation techniques of both continuum and discrete numerical models, especially with mimicking actual fracture processes on digital image micrographs. New scientific frontiers in wood moisture research have been tackled with the potential to evolve into long-term effort to resolve previously poorly understood fracture phenomena in wood when subjected to varying humidity conditions.
Data: CORDIS, © European Union
Project objective
The primary objective of the proposed research program is to develop profound analytical, numerical andexperimental base to predict the response of structural components under common in-service conditions. Withthe hypothesis that the local wood behaviour under changing humidity conditions is non-linear, locallydominated by the material heterogeneities, the significance of the research program will be placed on developinga computational modelling framework that could realistically represent all interacting phenomena, yet capable ofyielding practical efficiency. In terms of novelty of proposed scientific approach, the experimental analysis willencompass phenomena pertinent to fracture criteria to be provided through Environmental Scanning ElectronMicroscopy (ESEM) and prediction of crack propagation path, and stress analysis under changing humidityconditions. Local material heterogeneities will be implemented via novel lattice fracture model, where thephysical microstructure is explicitly represented at the scale of dominant influence of non-continuum behaviour,allowing for capturing the paradigm of failure and progressive damage in the presence of humidity cycles.The hypothesis of acceptable serviceability performance of the surfaced green lumber will be exploredthrough the analysis of both longitudinal and transversal mechaho-sorption. Depending on the final structuraluse, experimental program needs to be performed in fracture mode I (opening mode), mode II (shearing mode)and mixed modes with cyclic moisture content changes. Moisture gradient throughout the cross-section at theloci of wood defects, as well as stress redistribution due to different rates of stress relaxation during drying andwetting cycles will be determined through the Finite Element Analysis and moisture diffusion models.
Original text from CORDIS.
Participants
- UNIVERSITAET FUER BODENKULTUR · VIENNACoordinatorCity levelAustria
Links
Data: CORDIS, © European Union