Influence of elastic stress field on subsurface cracks in Vickers indentation of BK7 glass

Abstract

In this work, the elastic stress field dependence of subsurface cracks in silicate glass during indentation is investigated with theoretical and experimental methods. An analytical model for the indentation elastic stress field is proposed to evaluate the evolution of subsurface cracks during Vickers indentation of silicate glass. To validate the proposed model, indentation cracking experiments were performed on BK7 glass with an instrumented indentation machine, and the morphology of subsurface cracks was detected using a laser confocal scanning microscope from the indentation cross sections. The results showed that the median crack, originating at the bottom of the plastic zone, propagated downward straightly, while two distinct lateral crack mechanisms occur adjacent to the elastic–plastic boundary and propagate in different directions. Furthermore, the measured values of the plastic zone radius and median crack depth were compared with the theoretical model results. It was found that the experimental measurements coincide well with the model predictions.