Failure of a borosilicate glass as a result of repeated impact has bee
n studied. Impact fatigue study was Conducted in an improved pendulum
type repeated impact apparatus specially designed and fabricated for d
etermining single and repeated impact strength. For elimination of the
effect of humidity, repeated impact tests were carried out under liqu
id nitrogen. Quasi-static measurements were determined under four-poin
t bending. Using a square waveform as applicable to the present impact
tests and fracture mechanics interpretation, the number of cycles to
failure during impact fatigue tests were predicted from quasi-static f
atigue measurements. It has been shown that repeated impact loading ha
s a deleterious effect on the failure cycles compared to slow stressin
g. The role of an added mechanical effect during repeated impacts has
been suggested in controlling the cyclic fatigue behaviour.