Development of Numerical Simulation Model and Formability Evaluation for Electrohydraulic Forming Process

Abstract

In the automotive industry, the consumption of advanced high strength steels and aluminium alloys is increased to reduce the weight of automotive parts. However, because these materials have lower formability, it is not easy to deform these in the general forming process. Therefore, high speed forming processes are introduced such as electrohydraulic forming, electromagnetic forming and explosive forming. High speed forming is a process that deforms a material at a speed of more than 100 m/s. This paper describes the electrohydraulic forming (EHF) process. EHF is high strain rate forming process based on the electric discharge in the fluid. This process can improve the formability of the material due to the high strain rate of 103 ~ 104 s-1 and it can reduce the experimental cost by using only one-sided rigid tool. In this study, numerical model of EHF was developed in LS-DYNA commercial program and it showed that the material could be deformed by electric energy input inside the fluid. In addition, forming limit diagram (FLD) at high strain rate condition was obtained from M-K theory as criteria of formability evaluation and it was applied to the results of numerical simulation. As a result, it was predicted that the material has no cracks or wrinkles at a given energy input.