会议名称：“2022世界木材日”研讨会暨第四届国际林联（IUFRO）林产品文化研究组讨论会
会议时间：2022年3月21日

报告嘉宾：Sara Florisson
嘉宾简介：瑞典乌普萨拉大学博士后研究员

摘要：

In the past twenty years, with the introduction of cross laminated timber, wood has become increasingly popular as a structural material. This, together with an increased computational power of the desktop computer has created a renewed interest in the three-dimensional computational modelling of the moisture-dependent mechanical behaviour of timber elements. Such models can contribute to the understanding of the long-term behaviour of timber structures and to the development of building standards to maintain a save transport, work, and living environment. In order to obtain realistic results with such models, calibration and validation is of essence.
A three-dimensional finite element model is presented that can describe the nonlinear-transient moisture flow and moisture-induced stress and deformations associated with wood for a wide range of engineering applications. The model is developed in a finite element and computer-aided engineering software that has strong computational abilities, an extended graphical interface, and advanced tools for pre- and postprocessing. To create more flexibility, the theory that is used to describe the constitutive models, the wood’s fibre orientation, and boundary conditions are implemented in so-called user subroutines. The numerical model was both calibrated and validated with three applications that cover the field of wood drying and long-term behaviour of wood. The beam elements studied in 79 each application showed complex three-dimensional stress and deformation states influenced by varying climate, fibre orientation, and heartwood and sapwood areas. The area within the cross section of the timber beams, where the annual rings aligned with the exchange surface, seemed especially prone to high tension stress related to the tangential material direction. Dependent on whether the beam experienced desorption or adsorption, this stress state varied between tension and compression, respectively. By including the heartwood and sapwood area to the cross section, well know phenomena such as stress reversal and casehardening could be detected within the cross section during drying.

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