Abstract: An innovative means to deform conductive materials at high deformation rates is through electromagnetic forming (EMF). In this process, a capacitor bank is charged with electrical energy (on the order of tens of kJ), which is quickly dissipated into a specially designed coil geometry. A magnetic field is generated which induces eddy currents and an opposing magnetic field in any conductive materials in the vicinity. The opposing magnetic fields produce Lorenz forces that deform any unconstrained conductive materials at high velocity rates (>200 m/s). The entire process is completed in less than 100 sec with induced strains which are greater than twice that achievable through quasistatic forming.
If the “flier” workpiece (launched via an EMF process or by another means) impacts a stationary workpiece at a sufficient velocity and appropriate angle, a solid state weld can be created. An interesting feature of this welding process is the presence of a wavy morphology at the interface. With a solid state weld, dissimilar materials can be joined without detrimental intermetallics being formed through melting and solidification.
In this seminar, research related to analytical modeling, numerical simulations, and experimental investigations of EMF and impact welding processes will be presented. First, an analytical model to predict the velocity of the material during EMF will be presented along with experimental validation. Also, analytical modeling will be used to demonstrate that the wavy morphology at the interface of impact welds is due to a shear instability. Finally, numerical simulations and experimental results will provide a weldability window based on the impact velocity and angle in the process. Both EMF and impact welding are innovative processes that provide unique capabilities for distinct manufacturing applications.
Bio: Brad Kinsey is a Professor and Chair of the Mechanical Engineering Department and also a Professor in the Materials Science Program at the University of New Hampshire. His research interests are in the area of the mechanics, materials, and manufacturing innovations for metal deformation processes, including control of deformation paths, high rate forming, impact welding, micro-forming, and electrically-assisted forming. In 2013, he served as the Assistant Director for Research Partnerships in the Advanced Manufacturing Office at the Department of Energy (DOE) and the DOE representative to the Advanced Manufacturing National Program Office. He received his Bachelor’s degree from the University of Michigan in 1992 and his Master’s and Doctoral degrees from Northwestern University in 1998 and 2001 respectively, all in Mechanical Engineering. His awards include a CAREER Award from National Science Foundation, the UNH Assistant Professor of the Year Award, the Ralph R. Teetor Award from the Society of Automotive Engineers, and being named a Fellow of the American Society of Mechanical Engineers and the Society of Manufacturing Engineers.