Civil Engineering Reference
In-Depth Information
FIGURE 5.46
Preform shape optimization problem —
Shape of the initial workpiece (cylinder), shape of the
preform to be improved, and shape of the desired final
part.
FIGURE 5.47
Initial forging sequence allowing us to obtain the right final part—Left side of the figure: end of the
preforming operation and location of the spline active parameters—Right side of the figure: end of the finishing
operation.
FIGURE 5.48
Optimal forging sequence minimizing the forming energy—Left side of the figure: end of the
preforming operation and shape of the optimized die—Right side of the figure: end of the finishing operation.
The corresponding total forming energy is 13% smaller than these of the initial design. The forging force
evolution with time is plotted in
Fig. 5.49
.
It can be noticed that the optimized preform makes it possible
to reduce by a factor of two the maximum forging force during the preforming operation. Also, during
the finishing operation, the force is decreased but its maximum value is not changed as it is governed
by the final required pressure to obtain a perfect filling.
In this case, the additional computational time due to the sensitivity analysis was less than 30% of the
total simulation time, so showing the efficiency of the method. The optimization algorithm exhibited a
fast convergence rate, while important changes of the die shape were produced, as shown in
Fig. 5.50
.
Preform Shape Design for a Two-Step Forging Sequence
The shape optimization method is not restricted to the optimization of an existing design but can also
be applied to the preform tool design without preliminary information. Besides its scientific interest, this
feature is very important, from a practical standpoint, when a completely new forging sequence has to
