Determination of plastic properties of metals by instrumented indentation using a stochastic optimization algorithm

International audienceA novel optimization approach, capable of extracting the mechanical properties of an elasto-plastic material from indentation data, is proposed. Theoretical verification is performed on two simulated configurations. The first is based on the analysis of the load-displacement data and the topography of the residual imprint of a single conical indenter. The second is based on the load-displacement data obtained from two conical indenters with different semi-angles. In both cases, a semi-analytical approach [e.g., Dao et al., Acta Mater. 49, 3899 (2001) and Bucaille et al., Acta Mater. 51, 1663 (2003)] is used to estimate Young's modulus, yield stress, and strain hardening coefficient from the load-displacement data. An inverse finite element model, based on a commercial solver and a newly developed optimization algorithm based on a robust stochastic methodology, uses these approximate values as starting values to identify parameters with high accuracy. Both configurations use multiple data sets to extract the elastic-plastic material properties; this allows the mechanical properties of materials to be determined in a robust way