Pulsed electromagnetic forming is based on high-voltage discharge of capacitors through a coil. An intense transient magnetic field is generated in the coil and through interaction with the metal work-piece; pressure in the form of a magnetic pulse is built up to do the work. Data on formability of two aluminum alloys employed for exterior (6111-T4) and interior (5754) automotive body panels will be shown. Comparison of traditional Forming Limit Diagrams obtained by stretching of aluminum sheet with hemispherical punch to the results on formability, where hemispherical punch is replaced by a coil will be provided. It will be shown that material formability in high-rate forming conditions can significantly depend upon interaction with the forming die: electromagnetic forming into an open round window provides only slight improvement in formability, while forming in a V-shape die or into a conical die indicates a significant improvement. An important part of the electromagnetic forming technology is the design of the coil. The coil failure modes and measures preventing them are discussed.

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A study of the effect of tool–sheet interaction on damage evolution in electromagnetic forming is presented. Free form and conical die experiments were carried out on 1 mm AA5754 sheet. Safe strains beyond the conventional forming limit diagram (FLD) were observed in a narrow region in the free form experiments, and over a significant region of the part in the conical die experiments. A parametric numerical study was undertaken, that showed that tool–sheet interaction had a significant effect on damage evolution. Metallographic analysis was carried out to quantify damage in the parts and to confirm the numerical results.

Please cite this article as: Mamutov, A.V., Golovashchenko, S.F., Mamutov, V.S., Bonnen, Jn.J.F.,Modeling of electrohydraulic forming of sheet metal parts, Journal of Materials Processing Technology (2014), http://dx.Highlights  Numerical model of EHF process is based upon LS-DYNA software  Practical approach to define energy deposition law in plasma channel is developed  Numerical model of EHF process has been validated experimentally  Results on multistage EHF of an automotive panel illustrated EHF capabilities ABSTRACT Electrohydraulic forming (EHF) is based upon the electro-hydraulic effect: a complex phenomenon related to the high voltage discharge inside the water filled chamber. The resulting shockwave in the liquid is propagated towards the blank, and the mass and momentum of the water in the shock wave accelerates the sheet metal blank toward the die. Methodology of numerical simulation of EHF processes was developed based upon LS-DYNA commercial code using Arbitrary Lagrange-Eulerian (ALE) Multi-Material formulation. The model incorporates Page 3 of 54 A c c e p t e d M a n u s c r i p t 3 energy deposition inside the plasma channel, expansion of the channel driven by high pressure inside of it, propagation of the pressure pulse through the water filled chamber in contact with the rigid walls of the chamber and with the sheet metal blank being deformed. Comparison of the numerical and experimental results was performed on maximum pressure measured on the wall of the cylindrical chamber employing the membrane method.The model was used to simulate multistage EHF of a complex geometry automotive part.Analysis of the results showed the complex nature of multistage EHF process: a clearly recognizable wave picture during the initial stage of the channel expansion which transitions to almost incompressible water flow during later stages.