Micromechanical modeling of master curve temperature shifts due to constraint loss

The effects of constitutive and local fracture properties on constraint loss effects in fracture toughness tests of small specimens was carried out within the framework of the MC-DeltaT method. Constraint loss (CL) decreases the temperature at a specified reference toughness. This temperature shift increases with decreasing: (a) specimen size, (b) ratio of the critical cleavage stress to yield stress and (c) strain hardening. The toughness-temperature curve shift due to CL increases with higher reference toughness and reference toughness-temperature. These results can guide the development and interpretation of small specimen fracture tests, as well as the use of even smaller specimens for particular applications, like comparative studies of irradiation variable effects on embrittlement. While they are only briefly noted in this work, additional consideration of both statistical and three dimensional size effects will be, carried out in the future. (C) 2002 Elsevier Science B.V. All rights reserved.