Initiation and propagation fracture toughness of solid wood under the mixed Mode I/II condition examined by mixed-mode bending test

Mixed-mode bending, double cantilever beam, and end-notched flexure tests were conducted using specimens of spruce, and the initiation and propagation fracture toughness under various mixed Mode I/II and pure Modes I and II conditions were determined. In addition to the actual fracture tests, finite element analyses were conducted and the results were compared with those obtained from the actual tests. The elliptical criterion was applicable in representations of the mixed Mode I/II initiation fracture toughness relationship, whereas the linear criterion was applicable to the propagation fracture toughness relationship.