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During the drawing of sheet metal between a die and a blankholder,
compressive hoop-stresses are developed which attempt to thicken or wrinkle
the flange. Previous work on this behaviour has ignored any effects due to
normal or planar plastic anisotropy. In this paper it is shown that the
blankholder pressure necessary to suppress wrinkling increases with decreasing
normal anisotropy (r) and increases with increasing planar anisotropy (AO.
The approximate plane strain conditions (daz = 0) operating in the flange can
be simulated by an edge-notched tensile specimen and this simulation demonstrates
the effect of texture hardening and softening upon flange wrinkling behaviour.
The results obtained can be interpreted valitatively by the use of anisotropic
plasticity theory.
The speed of drawing also effects wrinkling, in general, the number of
wrinkles decreases with increasing drawing speed. |
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