On the use of constraint parameter A(2) determined from displacement in predicting fracture event

The constraint based fracture mechanics methodology, J-A(2) method, has bee n used to interpret cleavage fracture recently. In all previous studies, th e constraint parameter A(2) was determined by stresses analytically calcula ted from finite element analyses (FEA). In the current paper, it is first d emonstrated that A(2) can be measured during a fracture test using the crac k tip opening displacement (CTOD). A single-edge-notched specimen under ben ding (SENB) is used to compare the A2 values determined from delta(5) displ acement and the stress components. Finally, cleavage fracture toughness val ues for A533-B reactor pressure vessel (RPV) steel at -40 degrees C obtaine d from test programs at Oak Ridge National Laboratory (ORNL) and the Univer sity of Kansas (KU) are interpreted using the J-A(2) analytical model. Part icular emphasis is placed on using the A(2) determined from CTOD to charact erize the fracture event. It is demonstrated that the effects of crack dept h.(shallow vs deep) and specimen size (small vs large) on the fracture toug hness from the test programs can be interpreted and predicted using J and t he constraint level A(2) measured from the displacement. (C) 1998 Elsevier Science Ltd. All rights reserved.