(Received 3 September 2014; accepted 30 December 2014)
Published Online: 2016
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Unlike mechanical properties, the fracture resistance behaviour of ductile materials depends upon the state of stress existing ahead of the growing crack-tip. For ductile materials, the fracture resistance, expressed in terms of J–R curve, goes on changing with crack growth. The J–R curves are influenced by the specimen geometry, size, crack-depth, and loading and boundary conditions, etc. Another complicacy arises in the ductile-to-brittle transition temperature regime, where the fracture toughness exhibits considerable scatter and dependency upon temperature. For structural integrity analysis of safety-critical components, fracture resistance data are required in the upper-shelf as well as in the transition regime in order to account for the design-basis postulated accidental loading conditions. It may not always be possible to carry out fracture tests on real-life components due to several limitations, including those of irradiation environment apart from the prohibitive cost and time required for the tests. Finite element (FE) analysis of the components with postulated cracks and loading conditions offer an impressive alternative to safety-analysts. In this work, experiments were conducted on two different types of fracture mechanics specimens not only in the upper-shelf but also in the transition regime. The effect of crack-depth on the fracture behaviour was studied using shallow-cracked and deep-cracked specimens. The size effect was studied using specimens with different thickness values. The effect of specimen geometry and loading condition was studied using a compact-tension and a single-edged-notched-bend specimen. For the FE analysis, nonlocal Rousselier’s damage model was used. We extensively studied the effects of several variables on the fracture toughness of a ferritic pressure vessel steel, which have not received much attention in the literature. Extensive experiments were conducted to verify the numerical simulation results of nonlocal damage models.
Samal, M. K.
Reactor Safety Division, Bhabha Atomic Research Centre, Mumbai,
Institut für Materialprüfung Werkstoffkunde und Festigkeitslehre, Universität Stuttgart, Stuttgart,
Stock #: JTE20140340