Improving the characterization of a hardening law using digital image correlation over an enhanced heterogeneous tensile test

This paper presents the development and the implementation of an identification procedure of the parameters of a work-hardening law in the frame of large plastic deformation. This identification uses a finite element model updating (FEMU) method based on both the total force and the full-field strain measurements obtained during a single tensile test performed with a non-standard sample designed by the authors. This sample has the merit, as detailled in a previous study [1], of enhancing simultaneously: (i) the heterogeneity of the strain field within the whole gauge area of the sample, (ii) the diversity of strain-paths, (iii) and the sensitivity of strain maps to the hardening parameters. The stability of the identification algorithm was tested on virtual tensile tests performed on the same sample type by adding perturbations to numerical simulation results. The identification algorithm is robust at least up to relative noises of 10% and 25% on the force and strain, respectively. The results show that the identification seems acting as a filter by eliminating nearly all added perturbations. The identification performed on a real test led to a good agreement between simulation and experiment on both strain fields and force–displacement curve. Finally, the improvement of the prediction of strain maps was validated by performing a tensile test on another non-standard sample [2] which was not included in the identification protocol.

► The mechanical characterization of a material was improved using strain fields.
► Strain fields were measured over an enhanced heterogeneous tensile test sample.
► Good agreement was obtained on both strain fields and force–displacement curve.
► Validation on a non-standard tensile test unused in the identification protocol.