Review Eqs. (7.12) through (7.14) and explain which of these expressions can be applied to incremental forming. By the student. These equations are applicable because the deformation in incremental forming is highly localized. Note that the strain relationships apply to a shape as if a mandrel was present. 7.63 Referring to Eq. (7.5), it is stated that actual values of eo are significantly higher than values of ei, due to the shifting of the neutral axis during bending. With an appropriate sketch, explain this phenomenon. The shifting of the neutral axis in bending is
described in mechanics of solids texts. Briefly, the outer fibers in tension shrink laterally due to the Poisson’ effect (see Fig. 7.17c), and the inner fibers expand. Thus, the cross section
is no longer rectangular but has the shape of a trapezoid, as shown below. The neutral axis has
to shift in order to satisfy the equilibrium equations regarding forces and internal moments in
bending.
