Indentation fatigue of soda-lime-silica glass

Experiments were conducted to initiate cracks on soda-lime-silica glass by repeated indentation at a single point with different subcritical loads (0.1, 0.15, 0.25, 0.5 N) and a critical load of 1 N, similar to metal fatigue. It was observed that the diagonal length of the impression after each indentation cycle at different subcritical loads increased to a limit until hair-line radial cracks were initiated leading to eventual cracking. This phenomenon was analyzed based on cumulative residual stress and plastic deformation at the vicinity of the indentation causing eventual cracking