The effect of the press pressure P on the bending moment Mrs
was preliminarily investigated. The effect of press pressure P on
the bending moment Mrs is shown in Fig. 12, as an example. In the
preliminary investigation, the maximum residual stress rsmax was
fixed at 190 MPa so that the residual stress distribution might be
similar to the experimental value. The optimum press pressure Po
was defined as the pressure which decreases the moment Mrs to
zero.
metal, i.e. rsmax = 0 MPa, the press should not be given to the sheet
metal without the residual stress as it could cause the warp in the
opposite direction.
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