LAUSR

The heterogeneous strain field measured by digital image correlation in the central gauge area of a cruciform specimen permits to characterize the plastic anisotropic behavior of metallic sheets with a unique specimen [1]. Indeed, minor and major strains measured along several paths show a wide range of strain states, from uniaxial to equi-biaxial stress state. Thanks to the recording of forces along the two loading directions and to the strain field measurement, an identification of complex anisotropic yield criteria (like Bron and Besson criterion) is possible by inverse procedure. Then, a unique test is sufficient to evaluate the anisotropic behavior of the sheet. The aim of this work is to evaluate the effect of temperature and strain rate on the anisotropic behavior of AA6061 sheet. For this purpose, a biaxial device equipped with four hydraulic cylinders and accumulators (applied speed until 200mm/s), and with an air flow generator (applied temperature up to 160°C) is used to perform in-plane biaxial tensile tests for different conditions of strain rate and temperature. Numerical simulations of the equi-biaxial tensile test are then performed for these different experimental conditions. The numerical simulations are based on a FE model of the cruciform specimen including temperature and strain rate hardening dependencies while the Bron and Besson yield criterion has been calibrated only at room temperature and under quasi-static conditions. Finally, agreement between experimental and numerical evolutions of principal strains and strain paths ratios along three specific profiles is compared and the relevance of using only one experimental condition (room temperature and quasi-static strain rate) to calibrate the yield criterion is discussed. © 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (https//creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the scientific committee of the 23rd International Conference on Material Forming.