Revised eta-Factors and J-CTOD Relationships for SE(B) Fracture Specimens Including 3D Effects and Implications for Fracture Toughness Measurements

This work provides revised eta-factors derived from CMOD records and J-CTOD relationships applicable to estimate the J-integral and CTOD in SE(B) specimens with varying crack size and specimen configuration. Very detailed non-linear finite element analyses for plane-strain and 3D models provide the evolution of load with increased crack mouth opening displacement, which is required for the estimation procedure. The analysis matrix considers SE(B) specimens with W = 2B and W = B configurations with and without side grooves covering a wide range of specimen thickness, including a precracked Charpy (PCVN) specimen. Overall, the present results provide validation of the J and CTOD evaluation procedure currently adopted by ASTM E1820-11, while at the same time giving improved estimation equations for J and CTOD incorporating 3D effects which enter directly into more accurate testing protocols for experimental measurements of fracture toughness values using 3P SE(B) specimens.