EXPERIMENTAL AND NUMERICAL INVESTIGATION OF VOID NUCLEATION IN AN ALMGSI ALLOY

The nucleation of microvoids from second phase particles in an AlMgSi alloy has been investigated. The work has comprised detailed stress an alyses of elastic particles situated in an elastic-plastic matrix as w ell as damage mechanics analyses of the ductile fracture behaviour of smooth and notched axisymmetric tensile specimens. Based on the microm echanical analyses of isolated particles, general expressions relating local stresses in the particles to the stresses on a mesoscopic (cont inuum) level have been derived. These relationships have been incorpor ated into the classical Gurson model. Combined with a failure criterio n based on a physical coalescence mechanism, a calibration with experi mental results enabled the establishment of a set of micromechanical p arameters which are transferable between different stress triaxialitie s.