Repeated Indentation Effect On Lead Alkali And Soda-Lime Glass Under Subcritical Loads Prior To Crack Initiation

Fatigue related fracture studies on brittle materials has become predominant in recent times due to large application of such materials in different areas encountering fluctuating stresses. Among several methods adopted for fatigue studies, indentation is one of them. Unlike the conventional method involved in initiating a crack with a critical load followed by repeated indentation at the same spot for crack growth & fatigue studies, this study was carried out with Vicker's indentation on lead alkali & soda lime glass to initiate cracks by repeated indentation at a singular point with subcritical loads of 0.1N, 0.15N, 0.25N, 0.50N & 1.0N. The diagonal length was measured after five cycles. The increase in these lengths to a limit when surface crack initiated was attributed to the increase in the plastic deformation with repeated cycling.