Polycrystal-plasticity simulation of six and eight ears in deep-drawn aluminum cups

The formation of earing during cup deep drawing is simulated from crystallographic texture by means of a polycrystal-plasticity model introduced recently [O. Engler, S. Kalz, Mater. Sci. Eng. A 373 (2004) 350–362]. The capabilities of the earing model are validated with five examples of the typical two-, four-, six- and eight-ear profiles of commercial aluminum alloy sheets. Besides analysis of the experimental textures, earing simulations are performed with synthetic textures, including ideal texture components, mixed cube-and-rolling textures as well as computer-simulated rolling textures, in order to study the impact of the various texture components on earing. The polycrystal-plasticity simulations corroborate the common knowledge that four-fold earing with peaks under 0° and 90° are caused by the cube recrystallization texture, while rolling textures produce 45° earing. Mixed textures comprising both cube and rolling texture components lead to more complex cups with eight, six or only two ears, with a smooth transition between these three cases. Transition orientations along the deformation path from the cube recrystallization texture to the rolling texture give rise to an appreciable asymmetry of the cups, where the 0° ears are higher than the 90° ears. This asymmetry results in six-fold earing and, in extreme cases, in two-fold earing with pronounced ears under 0° and 180°.