Material model for wood

Wood is highly anisotropic and shows ductile behaviour in compression and brittle behaviour in tension and shear where both failure modes can occur simultaneously. A 3D material model for wood based on the concepts of continuum damage mechanics was developed. A material subroutine containing the developed model was implemented into a standard FE framework. Eight stress-based failure criteria were derived in order to formulate piecewise defined failure surfaces. The damage development of wood was controlled by nine damage variables. Embedment tests using three different wood species (spruce, beech, azobé) were carried out whose results were compared to modelling outcomes. The failure modes could be identified and the general shape of the load-displacement curves agreed with the experimental outcomes up to a numerical limit.