Quantification of crack volumes in dynamically damaged soda-lime glass

Abstract

In this paper we present a novel test methodology for the generation of varying degrees of pre-damage in small soda-lime glass cylinders by dynamic loading in combination with a subsequent contactless damage quantification. In the first step, 13 glass specimens are placed in demountable aluminum confinements. The confinements are then impacted by flyer plates at different impact velocities between about 70 m/s and 400 m/s. Two high-speed cameras are used to investigate the velocities and the planarity of the impacts. Afterwards, three-dimensional visualizations of the recovered specimens are generated using conventional CT-imaging at a micro-CT-device and phase-contrast imaging at a beamline of a synchrotron. A concept is developed to determine the crack volumes by means of a region-growing algorithm. For five selected specimens, the mean total crack volume is determined as a function of the impact velocity. The developed methods are a first step to improve the predictive power of existing numerical simulation models of glasses and ceramics in scenarios with high velocity impact or ballistic penetration. In the specimens, defined, quantifiable damage is generated that can later be characterized, e.g. in triaxial compression tests, to obtain damage-dependent yield curves. This concept turns out to be a significant improvement in comparison to the characterization tests of previous studies, which used loosely poured glass quartz powder or specimens that had been pre-damaged quasi-statically without quantification of the degree of damage.