A prediction of the fracture toughness of hardwoods in the sliding mode

This research was undertaken to establish prediction relationships for the fracture toughness of diffuse-porous hardwoods in the sliding mode and in the TL fracture configuration. Tests were conducted on three diffuse-porous hardwoods of the United States and four diffuse-porous hardwoods from Cameroon. Fracture toughness was calculated using a calibration function developed for wood beams with end splits and applicable to all wood species. A procedure was used to predict the fracture toughness of clear wood. The prediction relationship is based on two of the most important variables used in wood mechanics: moisture content and specific gravity. The relations obtained can be used to predict the value of the mode II fracture toughness of diffuse-porous hardwoods with the knowledge of only moisture content and specific gravity. The residual stresses may have a reducing effect on the fracture toughness of wood in mode II. This effect is more serious at low moisture contents.