Prediction of damage by dynamic FLD criterion in high velocity sheet metal forming and experimental results

In This paper dynamic forming limit diagram has been investigated as fracture criteria for ST13 steel. In fact, effect of various strain rates has been studied. This fracture criterion is based on the Marciniak-Kuczynski (M-K) theory and the Solution of equations has been obtained by applying the Newton-Raphson method. After solution three forming limit diagrams have been created: independent strain rate, dependent strain rate and dynamic forming limit diagram. Dynamic damage criteria investigates forming limit diagram in every strain rate. It is observed that the forming limit is increased by increasing the strain rate, Also for considering the anisotropic and the elastic-plastic behavior of material, the Hill 1948 yield criterion and the Swift hardening rule are used respectively. Also this paper is concerned with the uniaxial tensile properties and formability of sheet metal in relation to the strain rate effects. In order to verification of the results several experiments have been done with a Drop Hammer that is a high speed impact machine. For comparison between quasi static and dynamic damage criterions, all of the stages of experiment were simulated in finite element software Abaqus and results are compared together.

Keywords:

Strain rate , forming limit diagram , quasi static analysis , anisotropic behavior