Y. Zhang, G. Daehn, the Ohio State University, Columbus, OH; P. L'Eplattenier, Livermore Software Technology Corporation, Livermore, CA; S. Babu, Edison Welding Institute, Columbus, OH
Magnetic pulse welding (MPW) is a collision welding process, similar to explosive/impact welding (EXW), but it utilizes electromagnetic force (EMF) as the acceleration mechanism. Therefore, the available energy is much lower than EXW and it makes the process safer and more reproducible for sheet seam welding. However, the available energy must be better focused and controlled. In the sheet seam MPW process, a flyer sheet is driven by EMF and it collides with a target sheet. True metallic bonding is achieved at the mating interface if contact takes place above a critical impact velocity at an appropriate impact angle. The impact velocity and angle are determined by the primary and induced magnetic fields. Both of these are strongly related to the geometry of the electromagnetic actuator and the discharge characteristics. An MPW launch system that will robustly provide bonding can either be developed empirically or through simulation. Here we attempt to provide the basis for a simulation-based approach to system design.The flat and the oblique MPW impact of AA 6061 and Cu 101 were analyzed using the newly-available electromagnetism module in LS-DYNA. This module allows performing coupled mechanical/thermal/electromagnetic simulations by the “Eddy current” approximation. The simulation can predict the impact velocities and impact angle, as well as the temperature distribution along the mating interface. The simulation results were validated with measurement by Photon Doppler Velocimetry measurement. It was found that the variation of the impact velocity and impact angle resulted in varied interface morphology and properties. Additionally, the simulation results indicated rapid thermal cycling of the mating interface or local melting of one or both of the weld constituents.
Summary: The work focuses on the experiment study and numerical simulation of Magnetical Pulse Welding process for Al alloy and Cu alloy sheet seam welding.
