Multiscale modeling of cleavage fracture and applications to structural integrity ...
| Grant number: | 12/13053-2 |
| Support type: | Regular Research Grants |
| Duration: | September 01, 2012 - February 28, 2015 |
| Field of knowledge: | Engineering - Mechanical Engineering |
| Principal Investigator: | Claudio Ruggieri |
| Grantee: | Claudio Ruggieri |
| Home Institution: | Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
Abstract
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", Sigma_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 the Weibull stress (Sigma_w) as the effective crack driving force. However, despite some recent advances in the methodology to characterize fracture toughness in ferritic steels based upon the Weibull stress parameter, several open questions still remain related to its effective application to defect assessment procedures and life extension programmes for in-service structures. Within such context, 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 determine the reference temperature, T0, using the Master Curve methodology. (AU)
| Articles published in Agência FAPESP Newsletter about the research grant |
| Nuclear reactor safety assessment model wins award in the US |