Probabilistic modelling of Hertzian fracture of glass by flying objects impact in bad weather

Impact of hailstone and flying debris in extreme weather conditions is a major contributor to damage to glazing panels and other types of building facades. Localized damage to the glazing panel in the form of Hertzian fracture is controlled mainly by the amount of force that is developed at the point of contact. Weibull statistics forms the foundation of contemporary probabilistic models designed to estimate the value of the limiting force to result in Hertzian fracture. This conventional approach to probabilistic modelling has significant shortcomings as the calibrated probabilistic parameters have to be specific to the type of installations. The alternative approach of predicting risks of Hertzian fracture is by stochastic simulations of Griffith flaws. This paper presents an adaptive stochastic simulation methodology for predicting risks of Hertzian fracture of glass which is subject to the impact by hail and flying debris. The proposed simulation model has been verified experimentally for annealed glass based on comparison of the simulated contact force values against results from experimental measurements. The introduced simulation procedure has been used for assessing the risk of Hertzian fracture in both annealed and toughened glass. The use of the adaptive stochastic modelling methodology for predicting Hertzian failure in scenarios of hail impact is illustrated in this paper by examples.