LAUSR

Abstract The failure behavior of wood, a complex natural composite, highly depends on structural features on several lower length scales. Thus, a new approach for the prediction of failure mechanisms of wood is proposed, aiming at a better description of mechanical processes in wood by taking the influence of microstructural characteristics into account. Previously proposed failure criteria for wooden cells are now linked to unit cells at the annual ring scale. Extensive investigation of load combinations allow the identification and classification of the main failure mechanisms of clear-wood. Based on these findings, a multisurface failure criterion is formulated, indicating brittle as well as ductile failure mechanisms and giving interesting insight into the failure behavior. A new algorithm is presented, which enables the simultaneous description of plastic failure and cracking within numerical simulations. Finally, the failure criterion is validated for biaxial experiments and applied to a timber engineering example.