Modelling of the Charpy impact test in the DBTT range.

The finite element method was used in order to compute the energy balance and the stress-strain distribution in the Charpy V-notch specimen. Inertial effects were taken into account by a fully dynamic computation. It was shown that inertial oscillations are damped by viscoplasticity ahead the notch and vanish rapidly. 3D modelling is needed since large scale yielding and ductile crack growth occur. The ductile crack front is curved, which is important to account for in order to correctly describe the stress distribution in the specimen. Ductile crack growth in Charpy specimen was predicted by the GTN (Gurson-Tvergaard-Needleman) model. The GTN model allows a good failure prediction with strain rate and temperature independent damage parameters