Determining elastic–plastic properties from indentation data obtained from finite element simulations and experimental results

Abstract

Various approaches have been proposed to determine the material properties of power law materials, based on dimensionless analysis and the concept of a representative strain. In this work, non-linear optimisation algorithms are developed and integrated with Finite Element (FE) analysis to determine and improve the accuracy of the elastic–plastic mechanical properties of a power-law material without the concept of dimensionless analysis and a representative strain. The optimisation approach shows that a unique set of four key material properties of a given material (Young's modulus, Poisson's ratio, yield stress and work hardening exponent) can be determined from the loading–unloading indentation curve of only a single indentation curve, without the need for using results from two or more indentations. Different geometries of indenters (Conical, Berkovich and Vickers) are used with various initial values to test the robustness of this approach. Two types of target indentation loading–unloading curves are used; simulated target curves (obtained from FE analysis) and experimental test data with some random errors. The results show that the non-linear optimisation approach produces impressive accuracy when using a simulated FE loading–unloading curve, but is less accurate when a real-life experimental loading–unloading curve is used.