A STATE-OF-THE-ART REVIEW OF FAILURE OF WOOD UNDER I/Ⅱ MIXED MODE FRACTURE

For the design and the safety assessment of wood structures, an adequate knowledge of wood fracture behavior is important. Due to the complexity in its structure, wood is naturally anisotropic in the macroscopic scale, which makes it more di-cult to study wood failure based on fracture mechanics than to study isotropic materials. Therefore, only fractures of pure mode I and pure mode Ⅱ were given a considerable attention. Wood structural members are, however, often subject to the mixed mode fracture in reality, and the mixed mode fracture is now one of hot topics in the fracture studies. This paper gives a literature review on the wood mixed fracture from two aspects:the fracture criterion and the testing method. After an introduction of some empirical and physical models to predict the mixed mode fracture failure of wood, a comparison is made among these models using the test data in the literature. Various test methods are reviewed, with focus on fractures of mode I and mode Ⅱ combined. Some issues for future studies are highlighted.