STATIC AND IMPACT FATIGUE BEHAVIOR OF BOROSILICATE GLASS

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.