Thermal shock effect on the glass thermal stress response and crack propagation

摘要

Window glass breakage in a building fire could change the oxygen supply because of the entrance of fresh air. To investigate the break behavior of window glass under various rates of temperature rise, a finite element method was employed to solve the linear dynamic response equilibrium of the system. The Coulomb-Mohr criterion and SIFs based mixed-mode criterion were employed to predict the crack initiation and growth, respectively. A total of 12 rates of temperature rise were designed from 150 K/s to 0.75 K/s for a centre- heated and edges-shaded glass pane. The maximum thermal stresses are located at the shaded part between the hot and cool glass layer, which is where the cracking is initiated. Under a rapid rate of temperature rise, a smaller temperature rise could result in a bigger dynamic stress which is then followed by crack initiation. Under a slower rate of temperature rise, the dynamic effect becomes weaker and the thermal stress can be evaluated using the static method.