Publications de Stéphane Vernède

A mesoscale granular model for the mechanical behavior of alloys during solidification

Michel Rappaz, Stéphane Vernède, Jonathan Dantzig

We present a two-dimensional granular model for the mechanical behavior of an ensemble of globular grains during solidification. The grain structure is produced by a Voronoi tessellation based on an array of predefined nuclei. We consider the fluid flow ca ...

Elsevier2009

Prediction of solidification behaviour via microstructure models based on granular structures

Michel Rappaz, Stéphane Vernède, André Phillion

Two important factors affecting hot tearing - semi-solid constitutive behaviour and grain percolation - have been simulated through the use of microstructure models based on granular structures. The semi-solid model geometry is based on a modified Voronoi ...

Maney Publishing2009

Two-Phase Modeling of Hot Tearing in Aluminum Alloys: Applications of a Semicoupled Method

Michel Rappaz, Vincent Mathier, Stéphane Vernède

Hot tearing formation in both a classical tensile test and during direct chill (DC) casting of aluminum alloys has been modeled using a semicoupled, two-phase approach. Following a thermal calculation, the deformation of the mushy solid is computed using a ...

2009

A granular model of solidification as applied to hot tearing

Stéphane Vernède

Hot cracking is a spontaneous failure of an alloy during solidification. It is a severe problem for casting industry as it reduces the productivity of cast houses and limits the range of alloys compositions that can be industrially produced. Hot tears occu ...

EPFL2007

A Granular Model of Equiaxed Mushy Zones: Formation of a Coherent Solid and Localization of Feeding

Michel Rappaz, Stéphane Vernède

The gradual transformation of a mushy zone during alloy solidification, from a continuous liquid film network to a fully coherent solid, has been simulated using a granular model. Based on a Voronoi tessellation of a random set of nucleation centers, solid ...

2006

Transition of the mushy zone from continuous liquid films to a coherent solid

Michel Rappaz, Stéphane Vernède

While studies of solidification microstructures have focused mainly on the tips of the dendrites, the last stage solidification is equally important from the point of view of defect formation (porosity, hot tearing), mechanical strength build-up and precip ...

2006

Towards a Micro-Macro Model of Hot Tearing

Jean-Marie Drezet, Michel Rappaz, Vincent Mathier, Stéphane Vernède

Modelling of hot tearing must encompass several aspects: solidification, percolation of grains, stress/strain development, liquid feeding. The present contribution reviews recent progress made in this domain, both at the macro- and microscopic levels. At t ...

Trans Tech Publications2006