EXPERIMENTAL INVESTIGATION OF SPRUCE WOOD IN DIFFERENT MATERIAL-DIRECTIONS AND CONSTITUTIVE MODELLING INCLUDING KNOT EFFECTS

摘要

For the development of a constitutive material model for spruce wood different types of experiments are required. During the 1990's a test series on clear spruce wood subjected to biaxial states of stress has been performed [1]. These tests were designed for the investigation of stress states with their principal directions being oblique to the principal material directions L (longitudinal) and R (radial to the stem). However, there is still a lack of experimental information with respect to the tangential direction (T) and knots. This is the motivation for planning additional test series in 2003. The influence of knots on the strength properties as well as the mechanical behaviour of the T-direction is necessary for realistic finite element ultimate load analyses of multiaxially loaded structural details as well as of shell structures made of wood. Uniaxial experiments in different material directions with knots were also performed in 2003. Results of these tests and attemptions for a elastic-plastic material model shall be presented and discussed in this paper.