A simple fracture toughness analysis of a ductile steel by means of 3D surface displacements

L.D. PAOLINELLI; G.E. CARR; J. PREDAN; N. GUBELJAK; M.D. CHAPETTI

Kazan

Conferencia; 19th European Conference on Fracture; 2012

European Structural Integrity Society (ESIS)

The standards for characterization of fracture toughness of metals by means of fracture tests are focused on the calculation of fracture toughness parameters as the CTOD or the J-integral based only on the in-plane displacements and the load records of the specimen tested. Although fracture mechanics is a three-dimensional problem, the out-of-plane displacements of the specimen are not treated in those documents. Since 3D displacement measurement is available for experimentation it results interesting to investigate fracture mechanic problems in standard specimens. In this work, the fracture toughness of a structural steel is assessed by means of standard tests on SENB specimens, acquiring 3D surface displacements by DIC measurements. The out-of-plane displacements near the crack tip are evaluated to infer the initiation of stable crack propagation. It is found that the estimated critical toughness values are in good agreement with those predicted from R-curves. Hence, a simple alternative method for critical fracture toughness determination by means of 3D surface displacement measurements is proposed.