How the risk of failure in lifetime of tempered glass depends on the size of NiS inclusions and heat soak test duration

Abstract

The probability of breakage in service lifetime of heat-tempered glass panes contaminated by nickel sulfide inclusions is estimated with a multiscale micromechanically motivated statistical theory, which considers the effects of the heat soak test (HST). Short and long HSTs differently affect the phase transformation of NiS of diverse chemical composition, whose increase in volume can break the glass. The main hypothesis, corroborated by experiments, is that there is a lower limit for the size of NiS stones below which no crack can be initiated from the volumetric expansion. The catastrophic propagation of nucleated fractures in the long term is modeled through a rescaled critical stress intensity factor, which accounts for the subcritical crack propagation and the slow phase transformation of NiS. A parametric analysis evidences how the failure probability is strongly affected by these parameters, depending on the holding time in the HST. Tailored experimental activity is suggested for the proper calibration of the model.

Morphological characterization and reconstruction of fractured heat-treated glass

“…Although structural glass, mostly in the form of laminated glass, has been increasingly used in modern architectures [1,2], safety concern still arises as glass may have sudden failure due to its brittleness [3,4]. Different factors such as external loads [5,6] and internal defects [7][8][9] can result in the fracture of glass layer, which significantly damages the load capacity of structural glass. In engineering practice, damaged glass members are unlikely to have an immediate replacement and might sustain further destructive load, e.g., projectile impact in windstorms [10] and multiple blasts in terrorist attacks [11].…”