Predictions of forming limit diagrams using crystal plasticity models

Crystal plasticity models are used in conjunction with the Marciniak-Kuczyn ski approach to predict forming limit diagrams (FLDs) of different annealed aluminium alloy sheet (AA6xxx series) with various initial crystallographi c textures. The numerically determined FLDs are compared with experimental data. Two distinct models are used for FLDs predictions. The first method i nvolves the calculation of yield surfaces from a rigid-plastic rate insensi tive crystal plasticity model without recourse to the use of analytical yie ld functions. In the: second method, the response of the material is based on an elastic-viscoplastic crystal plasticity model. Both methods take into account texture evolution during deformation. By taking into consideration the elastic part of the deformation, the elastic-plastic model can predict the shift of the forming limit curve minimum towards positive minor strain s. It is found that the Goss orientation {011}[100] present in the initial texture as well as the microstructure influence significantly the formabili ty. (C) 1998 Elsevier Science S.A. All rights reserved.