J'S DISABILITY TO CHARACTERIZE THE CRACK-TIP STRESS FIELDS ACCURATELY COULD EXPLAIN ALL THE TEST SPECIMEN SIZE EFFECTS OBSERVED FOR THE FRACTURE TOUGHNESS (J_C) OF A MATERIAL IN THE DUCTILE-TO-BRITTLE TRANSITION TEMPERATURE REGION

摘要

A large strain EP FEA was performed to reproduce the experimental results for 23 SE(B) specimen types and 156 specimens, which were tested in the DBT temperature region of the A533B steel. The applicability of the (4δ_t, σ_(22c)) failure criterion was verified to transfer J_c for specimens with and without constraint. The critical value σ_(22c) showed only 4% variation and the statistical nature seemed to be negligible. The cause of the TST effect on J_c was concluded as J's disability to characterize the crack-tip stress fields accurately.