Therefore, FEM results for punch load are in good agreement with (1) by about %25 differences between them.
Fig. 11 provides a comparison of the punch force variations versus punch stroke in various steps.
These results have extracted from numerical simulation. It is seen from fig. 11, the punch force for stage-2 has increased at end of punch stroke.
This demonstrates the deformed part in stage-2 is to be experiencing Ironing process at the end of punch stroke due to unsuitable clearance between punch and die