An elastic-plastic constitutive law for the description of uniaxial and multiaxial ratchetting

An elastic-plastic constitutive model is proposed to describe 1-D and 2-D r atchetting. The model is also able to give correct results for 2-D ratchett ing when only uniaxial identification is used, while no special threshold o r parameter is used for the case of non-proportional loading. The original feature of this model consist in the introduction of a ratchetting stress ( material characteristic) along with the maximal stress supported in the his tory of loading and the plastic strain at the last unloading. In this paper uniaxial and 3-D formulations have been described based on a numerical imp lementation in the software Code_Aster. Uniaxial and also multiaxial identi fications have been used. Simulations have been realized for proportional a nd non-proportional homogeneous cases, as well as for structures under anis othermal thermomechanical loading. The results of a benchmark on a structur e, comparing experiment, simulations by this model and some other phenomeno logical models, and a polycrystalline model are presented. An analysis of e rror margin due to the choice of Mises criterion is exposed. (C) 1999 Publi shed by Elsevier Science Ltd. All rights reserved.