Modeling of electrohydraulic forming of sheet metal parts

Abstract

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.

Comparison of quasi-static and electrohydraulic free forming limits for DP600 and AA5182 sheets

“…These oscillations are likely to be the results of unstable work of the ignitron, a high-voltage, low inductance switch enabling quick discharge of capacitors through the electrode system. Similar effects were observed in experimental waveforms reported by Mamutov et al (2015). However, the amplitude of oscillations reported by Mamutov et al (2015) were visibly smaller which is most likely due to the substantially larger energy of discharge: 12.1 kJ corresponding to 11 kV reported by Mamutov et al (2015) vs. 3.6 kJ corresponding to 6 kV in the present study.…”

“…Similar effects were observed in experimental waveforms reported by Mamutov et al (2015). However, the amplitude of oscillations reported by Mamutov et al (2015) were visibly smaller which is most likely due to the substantially larger energy of discharge: 12.1 kJ corresponding to 11 kV reported by Mamutov et al (2015) vs. 3.6 kJ corresponding to 6 kV in the present study. The pulse generator used in this study was designed primarily for an energy of discharge in the range of 15-20 kJ.…”

“…1), a blank can be progressively formed into its final shape in one tool by multiple discharges of the electrode system in order to extend the life of the die, as described by Mamutov et al (2015). Similarly, newer electrode systems, as described by Golovashchenko (2014), are capable of lowering the load on the electrode system if the discharges are conducted in multiple steps.…”

Acquisition and Evaluation of Theoretical Forming Limit Diagram of Al 6061-T6 in Electrohydraulic Forming Process

“…For the simulation efficiency, plasma part was used instead of the electrodes. This treatment is reasonable because many previous studies [21][22][23] have shown that the numerical model with the plasma part can represents the deformation results well instead of electrodes. The most important factor in the fluid parts is the plasma part that has the forming resource.…”

Numerical simulation of electrohydraulic processes

“…This software can simulate interacting of several fluids and deformable solids objects through using the Arbitrary Lagrangian Eulerian (ALE) algorithm which, in combination with Multi-Material technique and Fluid-Structure Interaction (FSI) technique, eliminates the problem of mesh distortion and allows solving the problem of moving liquids and gases inside of a closed complex shape volume [11]. In the context of EHF, a simulation of a discharge channel in liquid for the case of cylindrical symmetry was done in work [12], and for the case of a chamber with coaxial closely placed electrodesin works [13][14][15][16]. In these works, electric power laws were used to provide input in LS-DYNA for energy deposit laws into the discharge channel.…”