Prediction of Cleavage Fracture From Non-Sharp Defects Using the Weibull Stress Based Toughness Scaling Model

Non-sharp defects exhibit a higher resistance to cleavage fracture than sharp cracks. This study uses the Weibull stress based toughness scaling model to predict cleavage fracture initiation in Single Edge Notch Bend SE(B) specimens with notches of varying root radii. Numerical predictions are compared with the results of an experimental study of SE(B) specimens with similar notches. The predictions correlate well with the test results, indicating that the Weibull stress approach and toughness scaling model can be successfully applied to predict cleavage fracture initiation from non-sharp defects. However, care needs to be taken to ensure that calibration of the Weibull parameters references fracture toughness data from constraint levels that span the defect of interest. This ensures the model interpolates between the constraint states used for calibration, rather than extrapolating outside the range of applicability.