Fast four-dimensional tensile test monitored via X-ray computed tomography: Elastoplastic identification from radiographs
Résumé
A Projection-based Digital Image Correlation (P-DVC) method (presented in a companion paper) is extended to an integrated approach for the calibration of an elastoplastic law based on a single radiograph per loading step. Instead of following a two-step sequential procedure (i.e., first, measurement of the displacement field; second, identification), the integrated method aims at identifying few model parameters directly from the gray-level projections. The analysis of an in-situ tensile test composed of 127 loading steps performed in 6 minutes is presented. An isotropic elastoplastic constitutive law with free form hardening behavior (i.e., controlled by only 8 parameters) is identified and shows a very ductile behavior (up to 6.3 % strain before failure). A large improvement on the residual quality is shown and validates the proposed model and procedure. The obtained displacement fields revealed to be similar to those measured with no mechanical integration. A different parameterization of the constitutive law provides a very similar result, thereby assessing the robustness of the procedure.
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