Finite element simulations of sub-size Charpy tests and associated transferability to toughness results

Charpy-V test results are widely used for the surveillance program of RPV (Reactor Pressure Vessel) embrittlement by neutron irradiation. Service life extension of nuclear power plants and more stringent safety requirements increase the request for small test specimens such as sub-size Charpy ones. Furthermore, empirical correlation formulas between conventional Charpy-V and fracture toughness are often questionable. Therefore, prior to use reduced size specimens, different hypotheses have to be validated and this can only be achieved by combining the results of testing campaigns and numerical modeling. In this paper, emphasis is given to the finite element results that have been obtained in order to interpret the experimental results described in an associated paper ^[1]. In a first step, the purpose of the finite element simulations is to get a clear description of the global mechanical behavior of the speciments. It is demonstrated that the description of the dynamic nature of the test is not required for fracture mechanics purposes since a quasi-static simulation taking into account strain rate effects on the material response is sufficient. However, a 3D analysis is required even for cleavage failure mode. The second step is related to the transferability of fracture criteria. This task has been initiated at low temperatures using the Beremin clevage model ^[2] and in the ductile regime using the Rousselier porous model ^[3]. These results show good transferability potential and ongoing investigations concern the transition region.