2011-05-04
10:15 at HCI J 574

An atomistic Study of the Mechanical Response of Amorphous Materials

Anne Tanguy

Laboratoire de Physique de la Matière Condensée et Nanostructures, Université Claude Bernard, Lyon

Disordered Materials like usual glasses have very specific thermodynamical and mechanical properties. They are obtained by an appropriate mixing of species, or by a rapid quench from the liquid state. They are characterized by a very high Heat capacity at low temperature, a low thermal conductivity and a very high hardness in comparison with crystals of the same composition. The plastic flow localizes along shear bands. We have performed Molecular Dynamics study of the elasto-plastic response of Model amorphous materials (Lennard-Jones glasses, Stillinger-Weber glasses -- a model for a-Si --, and BKS glasses -- a model for a-SiO2--). We will show the analogies and the differences in the mechanical response of these materials, when submitted to different mechanical loads (Shear, Hydrostatic compression..). We will show evidence of finite-size effects in the global stress-strain behaviour of the different samples, and relate the global behaviour to specific atomistic motions. This will allow us to discuss local plastic criteria at different scales, as a function of different materials characteristics, like bond directionality or local order.