Experimental and Numerical Investigation of Void Nucleation in an AlMgSi Alloy

Abstract

Abstract:The nucleation of microvoids from second phase particles in an AlMgSi alloy has been investigated. The work has comprised detailed stress analyses of elastic particles situated in an elastic-plastic matrix as well as damage mechanics analyses of the ductile fracture behaviour of smooth and notched axisymmetric tensile specimens. Based on the micromechanical analyses of isolated particles, general expressions relating local stresses in the particles to the stresses on a mesoscopic (continuum) level have been derived. These relationships have been incorporated into the classical Gurson model. Combined with a failure criterion based on a physical coalescence mechanism, a calibration with experimental results enabled the establishment of a set of micromechanical parameters which are transferable between different stress triaxialities.

Experimental stress state-dependent void nucleation behavior for advanced high strength steels

“…For a homogeneous material, N n can be calculated from microstructural analysis of the volume fraction of second-phase particles and inclusions in the material. Chu and Needleman [36] and Søvik [66] , assumed 𝜀 N and s N, to be material-specific parameters that were constant for all stress states. To assess the strain-controlled nucleation assumption, the predicted numbers of nucleated voids within CP800 based on a strain-controlled nucleation assumption ( Eq.…”

Evaluation of CTOD resistance curves in clamped SE(T) specimens with weld centerline cracks

“…Note that the use of stress-controlled nucleation is usually accompanied by numerical difficulties. This is due to the fact that void nucleation (positive increment in porosity) may be followed by a reduction in effective stress (negative increment in stress) [99]. The stress-controlled nucleation model is as follows:…”