Dynamic Fatigue Of Soda Lime Glass With Subthreshold Flaws

The dynamic fatigue of soda-lime glass containing subthreshold flaws was measured in water at 25 and 85C. The apparent fatigue susceptibility parameter was 10 for subthreshold flaws compared to 14 for postthreshold flaws and the apparent activation energy was 26.0 kj/mole compared to 82.6 kj/mole. The fatigue of subthreshold flaws was thought to be a two stage process involving nucleation of a crack and then propagation of this crack to failure. By characterising the size of the crack at pop-in and the initiation time for crack pop-in as a function of stressing rate, a dynamic fatigue model for subthreshold flaws was developed to explain the results.