The purpose of this study is to highlight the role played by some important factors on one of the major phenomena encountered in industrial forming processes namely, the springback phenomenon. This latter significantly affects the geometry of the manufactured product, particularly in sheet metal forming where the target shape of the product as in other industrial processes has to be precisely obtained. Large automotive or plane body parts are specifically affected by this effect which complicates the tools design. The study focuses here on specific materials with high trend to develop heterogeneous strains during forming processes. Due to its hexagonal crystalline structure, titanium as well as other materials such as dual phase steels, have initial heterogeneous microstructures that grow stronger when plastic strain occurs. Heterogeneous microstructures induce the coexistence in the material of volumes with different mechanical properties even, in some case, with different mechanical behaviours. Therefore, accommodation between these volumes generates distributed internal stresses and important elastic energy storage. The macroscopic behaviour can be provided either by average phenomenological constitutive equation identical for all locations in the material or by integrating a set of local constitutive relations taking into account the variability of the behaviour as a function of the position in the material.

For the former, kinematic hardening is the part of the modelling that is assumed to take into account the elastic energy storage effect, especially when complex strain paths are involved. For the latter, elastic storage effect is directly computed and its effect on back and forward paths is obtained as a consequence of the modelling.

In this context, experimental and numerical studies of a 3-point bending test on titanium alloy are considered. First, a formal analysis is done to highlight the impact of heterogeneous distribution of mechanical properties of the material on the mechanical behaviour of the material. In particular, this aims to understand what could be formally the influence of the intrinsic structural heterogeneity introduced here by the means of a discrete probability distribution of hardening parameters on the plastic strain distribution.

Then, experimental measurements were carried out using an image analysis method to obtain a reference study-case. The effect on the prediction of the configuration of the material under bending of two kinds of constitutive modelling of plasticity is evaluated just before and after the springback phenomenon occurs. This distribution has indeed a direct effect on global elastic relaxation after tools removal. Conclusion on the efficiency of both modellings is thereafter drawn from the comparison of the simulation results.