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Plane Stress Deformation of Anisotropic Sheet Metals
Technical Paper
891248
Sector:
Language:
English
Abstract
A mathematical model is presented to help understand sheet metal
deformation during forming. The particular purpose of this model is
to predict the forming limit diagram (FLD). The present model is an
extension of a previous analysis by Jones and Gillis (JG) in which
the deformation is idealized into three phases: (I) homogeneous
deformation up to maximum load; (II) deformation localization under
constant load; (III) local necking with a precipitous drop in load.
In phase III the neck geometry is described by a Bridgman type
neck.
The present model extends the JG theory which was applied to the
right hand side of the FLD only. The main difference in treating
the two different sides of the FLD lies in the assumptions
regarding the width direction deformations. For biaxial stretching,
the right hand side, the minor strain rate is assumed to be
homogeneous throughout the process. However, for the left hand side
of the FLD, in the critical cross-section, the minor strain rate is
taken to be proportional to major strain rate. This is a critical
difference from the JG approach and permits the left hand side to
be computed with good accuracy.