Introduction of the real tip defect of Berkovich indenter to reproduce with FEM nanoindentation test at shallow penetration depth

Indentations tests have been performed on two standard materials SiO2and Si (100) using two Berkovich indenters presenting different tip defects. Estimations of the tip radii deduced from analyses of maximal applied load versus contact depth and stiffness versus contact depth curves have been compared for experimental observation of each indenter tip obtained with atomic force microscopy (AFM). Results indicate that the determination of the tip defect from data extracted form load–displacement curves is partly dependent on the mechanical properties of the tested material. Then, an original study is proposed to evidence the influence of the tip defect on mechanical response during indentation. Experimental AFM observations of the tip indenter geometries have been introduced in finite element software MSC MARC to reproduce indentation tests on bulk material surfaces. We demonstrated at very shallow penetration depth (less than 50 nm) that the real indenter tip defects have to be considered in the simulation runs, especially to identify accurately the rheological parameters of the tested surface.