The greater the compression on the surface, the greater the strength of chemically strengthened glass. But on the other hand, tensile stress is formed inside the glass, which can cause numerous cracks and breakage if scratched deeply. Therefore, to produce chemically strengthened glass that is strong and resistant to breakage, it is important to design the appropriate stress patterns in the glass substrate.
Meanwhile, the crack propagation in the strengthened glass is an extremely complex phenomenon with intricate branching of cracks, which is difficult to reproduce using conventional simulation techniques. To optimize the reinforcing stress, trial-and-error using many experiments such as drop tests, analysis of cracks, and observation of the fracture origin was indispensable.

This numerical analysis reproduces the crack propagation pattern well, which varies with the magnitude of stress stored in the strengthened glass (Figure 1). It also provides a detailed picture of stress waves during crack propagation with nanosecond time resolution (Figure 2).

These results will be published in Physical Review Letters and Physical Review E on August 4 (Japan Time).

Under its AGC plus 2.0 management policy, the AGC Group will promote technological innovation to provide products and solutions that add new value by utilizing this method for the strength analysis of glass and other brittle and composite materials.

Sources
Title:
[1] Simulation of catastrophic failure in a residual stress field (Physical Review Letters)
[2] Mathematical model and numerical analysis method for dynamic fracture in a residual stress field (Physical Review E)

Authors: Sayako Hirobe¹, Kenji Imakita², Haruo Aizawa², Yasumasa Kato², Shingo Urata², Kenji Oguni¹
1. Research Institute for Value-Added-Information Generation, Center for Mathematical Science and Advanced Technology, JAMSTEC
2. AGC Inc.
A portion of this research was supported by a grant from the Japan Society for the Promotion of Research (JSPS) (topic number: 20K14812).