Identification of the Anisotropic Plastic Behaviour of Sheet Metals at Large Strains

Abstract

The identification of the material properties in sheet metal is usually achieved using uniaxial tests performed along different texture directions. In this paper an experimental procedure to identify the plastic behaviour of sheet metals up to large strains using full field measurement is presented. The tests were conducted on notched specimens. That geometry generates a heterogeneous strain field which has been measured during the test using a digital image correlation system. The advantage of using an heterogeneous strain field in the identification procedure is that a complex state of stress–strain can be analyzed at the same time and much more information can be obtained in a single test. On the other hand the stress field cannot be directly computed from the test and a suitable identification procedure has to be developed. Here, the virtual fields method (VFM) adapted for large strains and plasticity has been used to identify the hardening behaviour and the anisotropy of the two materials. The values obtained with the VFM have been compared with the results coming from a standard identification made with uniaxial tensile tests.