Yasumasa Nakao

Brittleness of glasses by indentation

A method to estimate the brittleness of glasses is introduced by measuring the C/a ratios where C and a are characteristic crack and indentation diagonal lengths, respectively

Mechanical properties and fracture analysis of glass substrate for PDPs

A thermal shock test was carried out using high-strain-point glass substrates for plasma-display panels. From the fracture analysis, the fracture stress was determined and compared with the initial edge strength. It was observed that the edge strength greatly decreased because of micro cracks that formed on the glass surface during testing. Therefore, it is important to prevent the formation of micro cracks in order to avoid failure as well as to minimize thermal stress in the process. Fatigue is also an important parameter in preventing the failure of the glass substrate when the stress on it lasts for a long period of time.