Transferability of Fracture Toughness with Constraint
Constraint approaches to transferability of fracture toughness are examined. The different constraint parameters are defined and discussed. Special attention is given to the actual trends to use the plastic constraint in the Material Failure Master Curve
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Abstract Constraint approaches to transferability of fracture toughness are examined. The different constraint parameters are defined and discussed. Special attention is given to the actual trends to use the plastic constraint in the Material Failure Master Curve (MFMC) and the Material Transition Temperature Master Curve (MTTMC).
1 Introduction Mechanical properties are not intrinsic to material but depend on geometrical factors such as the specimen geometry, thickness, surface roughness and length, defect geometry such as the relative length, radius, or opening angle, loading mode, and environment. Material properties available from data banks are therefore to be considered as reference material properties, as results from standard tests. To use these reference properties for a structure and component which differ in terms of geometry and loading mode, a correction needs to be made, which is called transferability. The properties to be used in a structure Pstruct are deduced from the reference properties f ð pÞ and the transferability function f ð pÞ, where p is the transferability parameter. Pstruct ¼ Pref f ð pÞ
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G. Pluvinage (&) FM.C 57530 Silly Sur-Nied, France e-mail: [email protected] J. Capelle LaBPS – ENIM, 1 route d’Ars Laquenexy, CS, 65820, 57078 Metz, France M. Hadj Meliani LPTPM, FT, Hassiba BenBouali University of Chlef, Esalem City, 02000 Chlef, Algeria © Springer International Publishing Switzerland 2017 T. Boukharouba et al. (eds.), Applied Mechanics, Behavior of Materials, and Engineering Systems, Lecture Notes in Mechanical Engineering, DOI 10.1007/978-3-319-41468-3_7
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For fractures emanating from a defect where fracture mechanics can be applied, the transferability is sometimes treated with the concept of characteristic length or scale factor [1] but more often by using the stress constraint or the relative stress gradient. These transferability parameters emanate from the defect tip distribution (notch or crack). If we compare the stress distribution obtained in a reference situation (generally small scale yielding) with another general one, the stress distribution is modified in two ways: there is a shift of the stress distribution and a small rotation. These modifications of the stress distribution are considered as transferability problems. The shift of the stress distribution is introduced into the plastic constraint, which is used as the transferability parameter. In the literature, we can note the following constraint parameters: the plastic constraint factor L [2], the stress triaxiality b [3], the Q parameter [4], T stress [5] and A2 [6]. In this paper, the different constraint parameters are defined and discussed. Special attention is given to the plastic constraint in the Material Failure Master Curve (MFMC) and the Transition Temperature Master Curve (TTMC).
2 Constraints at Defect Tip Constraint is considered as a modification of the defect tip distribution under the effects of specimen or defect geometries or loading mode. Different constraint
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