Experimental studies on fracture of notched white spruce beams

The fracture problem due to the singular stresses arising from the sudden change of geometric properties around cracks and notches was studied both analytically and experimentally. The failure models of the cracked and the notched specimens were derived by using linear elastic fracture mechanics methodology, which led to the determination of the critical stress intensity factors. Experiments were conducted to determine fracture toughness for different modes as well as the effect of variations in the crack-front width, specimen size and moisture content. Subsequently, failure surfaces for cracks and notches were developed based on the experiments undertaken, describing in each case the interaction between mode I and mode II fracture toughness. To verify the reliability of these experiments, the results obtained were compared with the published literature. As an application, design curves for a 90 degrees-cracked beam and a 90 degrees-notched beam are presented. These curves allow the prediction of the failure loads due to the rapid crack propagation under different loading conditions.Applied Science, Faculty ofCivil Engineering, Department ofGraduat