A Theoretical Study on the Effect of Strain Rate on Forming Limit Diagrams

In spite of the fact that the experimental results indicate the significant effect of strain rate on forming limits of sheets, this effect is neglected in all theoretical methods of prediction of Forming Limit Diagrams (FLDs). The purpose of this paper is to modify the most renowned theoretical method of determination of FLDs (M-K model) so as to be able to take into account the effect of strain rate. To achieve this aim, the traditional assumption of preexistence of an initial geometrical inhomogeneity in the sheet has been replaced with the assumption of a preexisting material inhomogeneity. It has been shown that using this assumption, the strain rate would not be omitted from equations; thus it is possible to demonstrate its effect on FLDs. To validate the results, they are compared with some experimental data. The good agreement between the theoretical and experimental results shows capabilities of the proposed method in predicting the effect of strain rate on FLDs.

کلیدواژه ها:

Forming Limit Diagram ، M-K Method ، Sheet Metal Forming ، Strain Rate ، Strain Rate Sensitivity Index