Abstract: Based on the analyses for
mechanism of necking deformation of a sheet metal under plastic
tension, as stated on Part Ⅰ of the present paper, a new method
predicting the right-side curves in forming limit diagram (FLD)
of a sheet metal is advanced by this part of the present paper,
which clearly takes the strains at the onset of localized
necking instability as the limit strains of the formed parts
and employs a constitutive relation in form of non-quadratic
orthotropic yield function recently proposed by the present
author. In this predicting method, the dP1=0 is used as the
criterion to beginning the instable deformation process of a
sheet element, the dP1=dε2=0 is used as the conditions of the
onset of localized necking lines in the biaxial tension strain
field, and the developmental process of instable deformation
between these two kinds of instability is minutely considered by
the numerical integration. It is made known from applications on
to several kinds of materials that the predicted results are in
good agreement, the close degrees to the experimental data are
finer than that predicted by other existing theories.
Key words:
Forming limit diagram Predicting
method Mechanism of necking deformation Orthotropy Non-quadratic
yield criterion
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This project is supported by National Natural Science Foundation of China
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