Static and dynamic Brazilian disk tests for mechanical characterization of annealed and chemically strengthened glass

Abstract

The intent of this research is to determine the tensile strength and fracture behavior of annealed and chemically strengthened aluminosilicate glass under static and dynamic loading conditions using Brazilian disk (BD) tests. Owing to high brittleness and very small failure strain of glass, this test method is preferred to indirectly measure the tensile strength by compressive loading of cylindrical specimens diametrically instead of using direct tensile test. In this study, based on the BD principle, the static tensile strength is measured by using the universal testing machine and a modified SHPB with pulse shaper technique is used to measure the dynamic tensile strength of two types of glasses. The synchronous high-speed photography in both static and dynamic tests is used to capture the damage/crack initiation, crack pattern, and failure process of BD specimens. Also, the strain-time history was recorded from gauges directly embedded on BD specimens in both tests. The test results showed that two types of glasses under investigation are the loading rate-sensitive. In the case of annealed glass (AG), the average dynamic tensile strength was increased three times from the static strength and a substantial increase in tensile strength of chemically strengthened glass (CSG) was observed at high loading rate. The high-speed images and collected glass debris during BD tests are analyzed and discussed to explain the rate-sensitivity, fracture mode and tensile failure process of two types of glasses. The high-speed video suggested that the main central crack caused the splitting or failure in AG and in case of CSG the main central crack along with multiple cracks the splitting or failure occurred. Finally, the scanning electron microscope (SEM) images of collected glass residue of (AG) and (CSG) was also studied to illustrate the brittle fracture surface, crack pattern and deformation mechanism in two types of glasses.