Investigation of the effect of Berkovich and Cube Corner indentations on the mechanical behavior of fused silica using molecular dynamics and finite element simulation

Abstract

In this study, elastic modulus and hardness of fused silica were evaluated and then simulated by molecular dynamics (MD) and finite element analysis (FEA). The reduced modulus, hardness of the surfaces, and elastic modulus caused by the process along the depth of the indentation on the surfaces are evaluated by the nano-indentation method on the fused silica. The obtained results indicate that applying different indenters such as Berkovich and Cube-Corner reduces the amount and size of surface microcracks. The load-displacement of various indenters such as Berkovich and Cube-Corner with similar load at about 50 mN for the Berkovich shows a 400 nm displacement and a 1600 nm for the Cube-Corner indenter. In this study, the MD was used to describe the mechanical behavior of fused silica structures with atomic nanostructure as simulated at T-0 = 300 K and P-0 = 1 bar as the initial condition. The mechanical constants such as hardness (with Berkovich tip), elastic modulus (with Berkovich tip), and fracture toughness (with Cube Corner tip) of fused silica nanostructure can be calculated from this MD simulation in which the hardness of the atomic matrix is obtained at 8.84 GPa.