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Multiscale Modeling of Cleavage Fracture and Applications to Structural Integrity Assessments Using Subsize Fracture Specimens

Grant number: 16/26024-1
Support type:Regular Research Grants
Duration: May 01, 2017 - October 31, 2019
Field of knowledge:Engineering - Mechanical Engineering - Mechanics of Solids
Principal researcher:Claudio Ruggieri
Grantee:Claudio Ruggieri
Home Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Assoc. researchers: Rodolfo Figueira de Souza


Single-parameter and two-parameter fracture mechanics methodologies have some well-recognized limitations which motivate development of probabilistic approaches to brittle fracture. Such approaches can be extended in straightforward manner to analyze the mechanical integrity of structural components subjected to more complex loading conditions. In particular, probabilistic procedures incorporating local failure criteria (micromechanics model for brittle fracture) coupled do the finite element method describe the conditions for global structural failure in terms of a (local) probabilistic fracture parameter; these methodologies are most often termed local approaches. To describe brittle fracture driven by transgranular cleavage, a number of models explicitly adopt the "weakest link" theory to derive statistical functions incorporating the local (opening) stresses well at the crack-tip region. Here, the "Weibull stress", Sig_w, then emerges as an effective crack-tip driving force controlling fracture. This research focuses on the extension and, more importantly, new developments of structural integrity assessment procedures based upon a micromechanics (local) model. A central objective is to develop a more robust procedure for mechanical integrity and fracture analysis of structural materials, including nuclear structural components and reactor pressure vessels, using a modified Weibull stress, Sig*_w, proposed recently by Ruggieri and Dodds (2015) as the effective crack driving force. This research will have particular emphasis on the correlation and prediction of toughness values measured using small-sized precracked Charpy (PCVN) bend specimens to accurately assess the structural integrity of critical structural components. (AU)

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Scientific publications (6)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
BARBOSA, VITOR S.; RUGGIERI, CLAUDIO. A simplified estimation procedure for the Weibull stress parameter, m, and applications to predict the specimen geometry dependence of cleavage fracture toughness. INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING, v. 188, . (16/26024-1)
BARBOSA, VITOR S.; RUGGIERI, CLAUDIO. Fracture toughness testing using non-standard bend specimens - Part I: Constraint effects and development of test procedure. ENGINEERING FRACTURE MECHANICS, v. 195, p. 279-296, . (16/26024-1)
BARBOSA, VITOR SCARABELI; RUGGIERI, CLAUDIO. Experimental Measurements of J(c)-Values for a Low Alloy Structural Steel Using Nonstandard Bend Specimens and Evaluation of the Reference Temperature, T-o. MATERIALS PERFORMANCE AND CHARACTERIZATION, v. 7, n. 2, SI, p. 75-100, . (16/26024-1)
RUGGIERI, CLAUDIO; DODDS, JR., ROBERT H.. A local approach to cleavage fracture modeling: An overview of progress and challenges for engineering applications. ENGINEERING FRACTURE MECHANICS, v. 187, n. SI, p. 381-403, . (16/26024-1)

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