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# Identification of stress intensity factor by digital image correlation combined with finite element method

 Grant number: 15/11104-7 Support type: Scholarships abroad - Research Internship - Scientific Initiation Effective date (Start): August 20, 2015 Effective date (End): December 19, 2015 Field of knowledge: Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials Principal researcher: Rodrigo Bresciani Canto Grantee: Rafael Vargas Maginador Supervisor abroad: François Hild Home Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil Research place: Laboratoire de Mécanique et Technologie (LMT Cachan), France Associated to the scholarship: 14/03594-1 - Crack length measurement during the wedge-splitting test using digital image correlation, BP.IC Abstract The high temperature and corrosive environments in which castablerefractories are utilized involves high risks. In this context,the characterization of these materials becomes extremelyimportant, and an essential tool for the correct selection,application, development and researches in this area. However, there are some difficulties identifying the R-curve, anindication of microstructural properties that provides the crackgrowth resistance as a function of its length. One common way ofR-curve identification is using a semi-empirical methodology,which is dependent on the stress intensity factor, whosemeasurement is laborious and even unknown for some geometries. In this internship project is proposed to obtain the stressintensity factor using Digital Image Correlation (DIC) combinedwith Finite Element Method (FEM) on the Wedge Splitting Test(WST). The displacement field is experimentally measured with 2D-DIC andthe crack length is then estimated as one unknown of theoptimization problem. The displacements measured on the boundary,and one estimate of the crack tip location are used as boundaryconditions in the FE model. The measured displacement field isthen compared with the simulation results to extract the crack tiplocation and stress intensity factors as minimizers of the $\chi^2$norm of the difference between measured and simulated displacementfields. This methodology will be used to obtain mechanical parameters thatfit best the experimental results with computer simulations. Thestress intensity factor would then be measurable in complexgeometries, and computer simulations would consider the wakeeffects given by the mechanical union of aggregates aftercracking, whose parameters are yet to be known. (AU)