Plastic response of amorphous silicates, from atomistic simulations to experiments - A general constitutive relation

The continuum scale description of the plasticity of silicate glasses is a difficult task. In addition to significant amount of densification, it has been shown that, depending upon composition, there is a more or less pronounced coupling of yield stress with pressure. Moreover, the scant experimental results make it difficult it build up reliable, quantitative constitutive equations. To overcome the problem, we have recently shown that atomic scale simulations can be used to investigate the plastic response of amorphous silicates and we have proposed a generic analytical form for the constitutive relations of amorphous silicates (Molnár et al., 2016a. Acta Mat. 111, 129-137). Here we show how this generic constitutive relation can be turned into a quantitative description by calibration from micromechanics experiments. We consider the case of amorphous silica for which we have most complete sets of data.