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New developments in fracture toughness evaluation

: Schmitt, W.; Böhme, W.; Sun, D.-Z.

Schwalbe, K.H.; Berger, C. ; Engineering Materials Advisory Services Ltd. -EMAS-, Cradley Heath; Deutscher Verband für Materialforschung und -prüfung e.V. -DVM-, Berlin:
Structural Integrity - Experiments, Models, Applications. Proceedings of the 10th Biennial European Conference on Fracture
West Midlands: EMAS Publications, 1994
ISBN: 0-947817-73-5
European Conference on Fracture (ECF) <10, 1994, Berlin>
Conference Paper
Fraunhofer IWM ()
crack front tunnelling; critical void volium fraction characteristic length; ductile failure; dynamic tensile test; instrumented Charpy-V test; J-resistance curve; micromechanical material model; neutron-emblittled weld material; nuclear pressure vessel; strain-rate dependent Gurson model; strainrate; three-dimensional numerical stimulation

Micromechanical material models are applied to analyse ductile failure processes during tensile tests and Charpy-V tests. The parameters are used to predict J-resistance curves for neutronembrittled weld material of nuclear pressure vessels. To validate the approach, dynamic tensile tests and instrumented impact tests with notched and precracked Charpy specimens are performed and simulated. 'Re results suggest that the critical void volume fraction f(ind c) and the characteristic length l(ind c) are practically independent of strain-rate and specimen geometry. The tunnelling of the crack in the interior of the Charpy specimen is predicted in a satisfactory way by a three-dimensional analysis with a strainrate dependent Gurson model.