Investigation of forming limit of brass alloy c260 at high strain rate by using electrohydraulic forming process

Forming limit diagrams (FLDs) are useful tools for prediction of the instability of sheet in metal forming. The goal of this study is to evaluate the formability of 260 brass alloy sheets under various strain rates (particularly at high strain rate). Three types of experimental procedure were developed: Nakazima test (for determination of the FLD at quasi-static condition), hydrodynamic forming (for determination of the FLD at intermediate strain rate) and Electrohydraulic forming (for determination of high strain rate FLD). Electrohydraulic forming (EHF) is a high velocity sheet metal forming process in which two or more electrodes are positioned in a water filled chamber and a high-voltage discharge between the electrodes generates a high pressure to form the sheet. Arbitrary Lagrangian Eulerian (ALE) formulations coupled with fluid–structure interaction (FSI) algorithms (that are available in the advanced finite element code LS-DYNA) were used to the numerical simulation of process and design of sheet metal specimen geometries. It was found that the forming limits of brass 260 in EHF increased more than 11% relative to the quasi-static. In addition, the formability of this material under the hydrodynamic loading is 4% higher than quasi-static values.