Seminars

Glass is a truly ubiquitous material in our daily lives. In almost all cases, structural integrity of the glass is a design requirement (even if the glass itself is not inherently structural). From phone screens to space shuttle windows, EpiPens to cookware, none of these devices will operate correctly if the glass fractures or breaks. Predicting glass reliability over time can be difficult. We will discuss two of the complicating factors. First, cracks can propagate sub- critically at low load levels, an effect which is exacerbated by temperature and water exposure. Second, glass is a non-equilibrium material, meaning it is continually evolving to reach a lower energy configuration. In combination, these issues make accurate predictions of lifetime a challenge; especially, when one must guarantee very small amounts of propagation over decades or longer time scales. We will discuss how both sub-critical fracture and viscoelasticity can be viewed as transitions between metastable states and the relation between them at a slowly moving crack tip.