Highlights include:

• A Framework for Quantifying Crack Tip Constraint

• Constraint and Toughness Parameterized by T

• An Experimental Investigation of the T Stress Approach

• Statistical Aspects of Constraint with Emphasis on Testing and Analysis of Laboratory Specimens in the Transition Region

• Predictions of Specimen Size Dependence on Fracture Toughness for Cleavage and Ductile Tearing