Fracture investigation of wood under mixed mode I/II loading based on the maximum shear stress criterion

The main objective of this article is to present a new fracture criterion for predicting both crack growth initiation and crack propagation direction in wood specimens under mixed mode I/II loading. This criterion is based on distribution of the maximum shear stress in the crack tip vicinity. An accurate estimation of the damage zone effect in wood is the main advantage of this criterion in comparison with available ones. The variation compliance of damaged material due to growth of microcracks is considered by a suitable damage factor. This criterion is extended for specimens with arbitrarily oriented cracks with respect to the orthotropic axes. It is revealed that developed approach is more compatible with the nature of the fracture phenomena in wood. The superiority of proposed method has been shown by some verification cases for several available fracture test data.