Numerical simulation of a fracture toughness test of an Al6061-T6 aluminium alloy using a ductile criterion

• Numerical simulation of fracture toughness test on Al6061-T6 specimen.
• Geometry transferability of a ductile damage criterion in a high stress–strain gradient scenario.
• Microstructure and fracture surface analysis.
• Relation between optimum mesh size and microstructure.

Aim of the present paper is the evaluation of the capability of a ductile damage criterion to numerically predict (finite element model) the behaviour of Al6061-T6 compact specimen C(T) involved in fracture toughness tests. The parameters of the damage model have been previously calibrated with mono and multiaxial tests; the current work is an exploitation of such calibration in a different framework, in order to check its geometrical transferability even in a scenario dominated by a high strain gradient.Finite element analysis has been carried out using the commercial finite element software ABAQUS 6.12 and a quasi-static explicit framework. The advantages and the possible drawbacks of the application of this kind of macroscopic failure criteria in a scenario dominated by very localized phenomena, thus involving material at grain size, are herein discussed. Due to the localized nature of the problem, mesh size potentially plays a relevant role in the failure, hence various mesh sizes have been analyzed and their performance is discussed on the basis of metallographic analyses.