Representative indentation yield stress evaluated by behavior of nanoindentations made with a point sharp indenter

• We propose a representative indentation yield stress Y* that characterizes local plastic deformation due to nanoindentations.
• We modify the indentation elastic–plastic index with the representative indentation elastic modulus E*, Y* and the inclined face angle β of a conical indenter.
• We propose how to determine Y* from experimental indentation data and an empirical equation.
• We confirm the validity of the empirical equation in actual nanoindentation experiments.

In order to evaluate local plasticity, a numerical analysis is carried out on conical nanoindentations simulated with a finite element method. A representative indentation yield stress Y* that characterizes the nanoindentation is derived in order to represent the local plasticity properly in terms of the yield stress Y, plastic strain hardening modulus Ep, Poisson's ratio ν and the inclined face angle of the indenter, β. Y* can be empirically evaluated as a function of the representative indentation elastic modulus E*, the relative residual depth ξ and β, where ξ is defined as ξhr/hmax with the maximum penetration depth hmax and the residual depth hr. Nanoindentation experiments confirmed the validity of the empirical equation for evaluating the yield stress.