fraktaler

Sigurdur Ormarsson: Modelling of wood and timber structures

Välkommen till en föreläsning i seminarieserien i matematik.

Föreläsare/Lecturer

Sigurdur Ormarsson, professor i beräkningsmekanik för trä och i träbyggnadsteknik, institutionen för byggteknik, Linnéuniversitetet

Titel/Title

Modelling of wood and timber structures

Sammanfattning/Abstract

Wood is a biological and environmentally-friendly material with a large ecological benefit as a building material. Yet, wood is a complex inhomogeneous, hygro-mechanical, moisture-sensitive and spiral orthotropic material that needs advanced analysis, especially for timber elements and structures exposed to varying climate conditions. Moisture related distortions (and fracture) in timber is, for example, a frequent complaint of solid timber products worldwide. The work presented here deals with development of a three dimensional finite element model to simulate moisture related stresses and (long-term) visco-elastic deformations in solid wood and laminated timber products. The constitutive model used takes account of elastic, hygroscopic, mechano-sorption and creep strain behaviour.

To solve the problem of warping, it is important to determine its causes and how it can be reduced. A way to improve the shape stability of laminated timber products is to optimally glue wood pieces together. In this work, the three dimensional distortion model was used to study how different parameters have influence on the shape stability of different laminated engineering wood products.

The theory presented has also been implemented for a special beam element for wood to effectively simulate the moisture-induced deformation and stresses in large timber structures during their whole service life. Finally, this theory has also been developed for axisymmetric elements to simulate growth stresses that occur in growing trees.

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