A Two-Step Inverse Analysis Approach Used to Identify the Mechanical Properties of Metallic Materials Subjected to Large Plastic Strains. Applications to Local Investigations of Surface Layer’s Behaviour

Abstract

The aim of this research work is to improve the experimental and numerical analysis of the local mechanical properties corresponding to metallic alloys used by bulk forming processes. A non-conventional upsetting test and an optimal direct extrusion device designed by the authors are used in order to identify the constitutive rheological equations and the friction models, starting directly from measured load-stroke curves. A two-step inverse analysis strategy is thus proposed starting from a complete Finite Element Model of the experimental tests and using a strong numerical coupling of the FEM with an optimization platform in charge with the automatic parameters identification. The obtained results are correlated with experimental investigations based on X-Ray, EBSD and hardness measurements concerning the microstructure and the local mechanical properties of the surface layer obtained from a conical extrusion process.