numerical evaluation of the effect of forming velocity on forming limit diagram (fld) of st14 steel using bifurcation theory and comparison with experimental results

forming limit diagram (fld) is an important diagram by which the formability of sheet metals is studied. strain rate is a very effective parameter influencing the fld which is, in turn, influenced by the forming velocity. in this work, forming limit diagram for st14 was investigated both experimentally and numerically. in addition, the effect of forming velocity was studied and the experiments were conducted at three different velocities, i.e. 10, 100 and 200 mm/min. in numerical simulation, bifurcation theory was used to determine the necking time. the experimental results were compared with the numerical results and it was shown that the forming limit is increased as the forming velocity increases