Mechanical analysis of indentation experiments with a conical indenter

Abstract

The finite element method was used to study the pyramidal indentation of elastic perfectly plastic (EPP) solids. The ratio of the effective elastic modulus, E*, to the flow stress, σ₀, ranged from 2.79 (quasielastic solid) to 2790 (quasirigid perfectly plastic (quasi-RPP) solid). The frictional shear stress was taken as equal to zero or its maximal value. First we analyzed the two-dimensional indentation with a rigid axisymmetric cone (semiapical angle θ = 70.3°). We determined the evolution with the indentation index, X = (E*/σ₀)cot θ, of the indent profile, the shape ratio, c = h_c /h where h (h_c ) is the indentation (contact) depth, and the hardness, H. The influence of friction becomes significant for X > 10. We validated our results by comparison with the results related to RPP solid and the results of three-dimensional numerical simulation of the Vickers and Berkovich pyramidal indentation for X = 1, 30 and 100. A method for interpreting the results of instrumented indentations is proposed and compared with the Oliver and Pharr method.