Optimisation procedure for parameter identification in inelastic material indentation testing

Abstract

The indentation of an inelastic material isotropic half-space with a spherical tip indenter is simulated using an in-house finite element code written in Fortran. In order to identify seven unknown material parameters (E and ? for elasticity; ?y,0, R, ?, Hkin and Hnl for plasticity), the simulation results must match as good as possible the experimental load-penetration curve obtained when indenting the inelastic material. This material parameter identification is performed using an optimisation procedure, i.e., one has to minimize the difference between the experimental curve and the simulated one. The optimisation procedure used here starts by applying a GaussNewton method, then continues using a Levenberg-Marquardt method. Using this optimisation procedure, the material parameter identification was successfully achieved for the considered indentation case study.