Fatigue limit in fused silica

The threshold stress intensity factor for sub-critical crack growth in fused silica was measured using the interrupted static fatigue (ISF) test and from observations of indentation crack growth under load. Good agreement was obtained between the two techniques with values of 0.31–0.34 MPa√m and 0.30±0.02 MPa√m, respectively. The relative advantages of the two experimental approaches are discussed.