PSI - Issue 13

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Gustavo Henrique Bolognesi Donato et al. / Procedia Structural Integrity 13 (2018) 1879–1887 Gustavo H. B. Donato and Felipe C. Moreira / Structural Integrity Procedia 00 (2018) 000–000

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Fig. 1. Similitude concept considering the one-parameter EPFM: (a) test specimen; (b) arbitrary geometry loaded under SSY conditions; (c) Plastic zone and J-dominance region in the crack-tip vicinity. Typical fracture mechanics specimens’ geometries: (d) Compact under Tension - C(T); (e) Single-Edge notched under Bending – SE(B); (f) Single-Edge notched under Tension – SE(T) loaded by clamps – c. 2. J dominance and the deformation limit - M parameter Paris, using studies of Landes and Begley (1972), was the first to suggest a pragmatic criterion to the evaluation of the validity limits of the J -integral as a stress intensity quantity from the theoretical background of the single-parameter EPFM. After Paris, several other researches (Landes and Begley, 1974; Landes and Begley, 1976; Mcmeeking, 1977) applied J as a failure criterion under elastic-plastic conditions, discussing the effects of plasticity on its validity. Finally, Shih and German (1981) created a systematic criterion to assess the validity of J -integral as a stress intensity quantity capable of describing the stress fields ahead of a crack ( J -dominance) in the form: �, � � � � , (1) where B is the specimen’s thickness, b is the remaining ligament, σ 0 is a reference stress (that can be the yield stress or the average between the yield and the ultimate tensile stresses – denoted σ flow ). After a detailed review of the literature regarding this theme, it could be observed the scarcity of M results (deformation limits) that could be used to characterize the validity limits of the EPFM based on J -integral. It was also found in the literature that M is very sensitive to the geometry being tested, the crack relative depth, the loading mode and the material properties. Consequently, it is very useful to investigate and propose M values in a structured manner considering a varying range of geometries, materials and loading modes. As a step in this direction, this work was conducted. 3. Materials and numerical procedures Three widely employed fracture mechanics geometries were considered in the study (Fig. 1d-f): Compact Tension C(T), Single-Edge notched under Bending SE(B) and Single-Edge notched under Tension SE(T). The first two geometries are recommended, for example, by ASTM E1820 (2018). The third geometry, in its turn, can be found in