Abstract
This article presents a three-dimensional wood material model implemented in finite element (FE) software which is capable of predicting the behavior of timber at the macro-scale taking into account the effect of any type of knot. The model was built in Ansys using the ansys parametric design language, such that the whole simulation process, including the creation of geometries, grain deviation, meshing and failure prediction, is automatically calculated by only introducing conventional measuring parameters of knots and locations of the pith. Knots are generated as elliptical, rotated and oblique cones. The local and global grain deviation is estimated by solving a multiphysics problem and equating the fibers of wood to the trajectory of laminar streamlines in 3-D. Wood is considered a transversely isotropic material with anisotropic plasticity in which the failure prediction is given by means of several phenomenological failure criteria. The model was validated with 4-point bending tests of Scots pine specimens showing errors in failure prediction of 5 %, errors in initial fracture location of less than 20 mm and errors of 9 % in photogrammetrically measured displacements of an average of 65 FE nodes, in which the heterogeneity of wood caused variations of up to 6 %.
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Acknowledgments
The authors acknowledge the support of the Spanish Ministry of Education for its financial support through the National Training Program of University Lecturers (FPU) and project AGL2009-11331, which was financed by the Spanish Ministry of Science and Technology.
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Guindos, P., Guaita, M. A three-dimensional wood material model to simulate the behavior of wood with any type of knot at the macro-scale. Wood Sci Technol 47, 585–599 (2013). https://doi.org/10.1007/s00226-012-0517-4
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DOI: https://doi.org/10.1007/s00226-012-0517-4