ABSTRACT
In the majority of real applications, structures behave under mixed-mode I + II loading. These mixed-mode conditions arise from external loading and from material anisotropy. The orthotropic directions of wood [longitudinal (L), radial (R) and tangential (T)] present large differences in stiffness and strength. As a result, fracture rarely occurs across the wood fibres, since its strength is much higher than in the radial and tangential directions. Consequently, cracks tend to propagate along the fibre direction independent of its initial orientation, thus inducing mixed-mode fracture conditions that should be accounted for in design, since they can drastically affect the strength predictions. Therefore, it is fundamental to study damage growth under mixed-mode I + II loading to establish adequate fracture criterion. In this context, the development of suitable experimental tests and manageable data reduction schemes for mixed-mode I + II wood fracture characterisation becomes a relevant research topic.
