Silicate glasses are archetypal brittle materials where surface flaws dictate practical strength. Although there is little variation in the major mechanical properties of most silicate glasses (elastic modulus, hardness and fracture toughness all vary by less than a factor of two with composition), the resistance to surface damage stands out, with sometimes variations by two orders of magnitude with moderate composition changes.

The reason is still elusive. However, it has been suggested that plastic flow and especially shear bands result in material damage, from which fracture initiates. Here, we propose to test this hypothesis extensively, using advanced micromechanics tools for detailed characterization of glass response as a function of composition, phase field models for the prediction of shear bands and damage, and molecular dynamics simulations to correlate the continuum scale parameters to atomistic rearrangement processes.