Predictions of forming limit diagrams using a rate-sensitive crystal plasticity model
A rate-sensitive crystal plasticity model is applied directly in conjunction with the Marcinial-Kuczyński approach to predict forming limit diagrams (FLD) for annealed FCC sheet metals. An isotropic slip hardening law is used. The simulations assume an initial thickness inhomogeneity in the form of a narrow band in the transverse direction of the sheet. This narrow band is slightly thinner than the nominal sheet thickness. By tracking the evolution of the band thickness with applied deformation, the limiting strains in the nominal sheet region can be calculated. The entire FLD of a sheet is determined by changing the strain path in the nominal sheet region. First, the FLDs of sheet with ideal crystallographic textures are analyzed to investigate analytically the influence of microstructure and microscopic properties. Two ideal orientations of rolling textures, \((101) [0 \overline{1} 0]\) (Goss) and \((001) [0 \overline {1} 0]\) (cube), are considered. Then the FLDs of sheets having other initial textures are predicted numerically. Finally, the effects of various factors on the forming limit diagrams are discussed such as: slip hardening, strain-rate sensitivity, initial imperfections, initial texture and yield surface shape.
scientific article; zbMATH DE number 755004