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ABSTRACT. This study addresses further developments of the evaluation procedure for J and CTOD in common fracture specimens based upon the  -method. Very detailed non-linear finite element analyses for plane-strain models provide the evolution of load with increased load-displacement to define the relationship between plastic work and crack-tip driving force ( J and CTOD) from which the  -values are derived. Further analyses based on the load separation method are also conducted to define alternative  -values against which factors  evaluated from plastic work can be compared. The analyses reveal that  -factors based on load-line displacement (LLD) are sensitive to plasticity changes at locations remote from the crack-tip region. Overall, the present results provide a strong support to use  -based procedures in toughness measurements for conventional SE(T) fracture specimens.
KEYWORDS. J -integral; CTOD; eta-factor; SE(T) specimen; Load separation.