Simulation of Vickers indentation of silica glass

The indentation response of glasses can be classified under three headings: normal, anomalous and intermediate, depending on the deformation mechanism and the cracking response. Silica glass, as a typical anomalous glass, deforms primarily by densification and has a strong tendency to form cone cracks that can accompany median, radial and lateral cracks when indented with a Vickers tip. This is due to its propensity to deform elastically by resisting plastic flow. Several investigations of this anomalous behavior can be found in the literature. The present paper serves to corroborate these results numerically using the discrete element method. A new pressure-densification model is developed in this work that allows for a quantitative estimate of the densification under very high pressure. This model is applied to simulate the Vickers indentation response of silica glass under various indentation forces using the discrete element method first, and then a discrete-continuum coupling method with large simulation domains to suppress the side effects and reduce the computational time. This coupling involves the discrete element method (DEM) and the constrained natural element method (CNEM). The numerical results obtained in this work compare favorably with past experimental results.