AbstractTwo specimen types, each from walnut and cherry wood, were prepared for tangential-radial (TR) and radial-tangential (RT) crack propagation systems at 65% of RH and 20°C before mode I and mode II fracture toughness was determined through Arcan tests. It was found that fracture toughness in mode I is in agreement with literature data. In the mode II test, however, the crack propagated in the direction normal to the shear plane and not parallel to it. The release rate of strain energy in terms of the opening failure in mode II was lower than that in mode I. It can be concluded that it is difficult to determine the fracture toughness of RT or TR propagation in hardwood specimens in mode II.
ISRM Suggested Method for the Determination of Mode II Fracture Toughness