MSE Colloquium: Dr. Anupam Vivek, Dynamic Manufacturing and Testing with Electrically and Optically Driven Plasmas

Research Scientist, Department of Materials Science and Engineering, The Ohio State University

Abstract

High strain rate behavior of materials is in itself an interesting field of research but it can also have interesting implications in manufacturing. For example, adiabatic shearing enables burr-free cutting of high strength materials with reduced punch forces; passage of a shockwave can relieve residual stresses in the material and therefore remove spingback; inertial stabilization of necking can improve formability of materials and most similar and dissimilar combinations of metals can be welded in the solid state by impact and without far field heating. Referred to as Impulse Manufacturing, where shock physics meets manufacturing, this field is growing in terms of applications, methods, diagnostics, characterization and modeling. This talk will focus on some of the most impactful recent developments in this field, including vaporizing foil actuator (VFA), photonic Doppler velocimeter (PDV) and laser impact welding (LIW), all of which have been pioneered at Ohio State. VFA utilizes the rapid vaporization of a thin metallic conductor due to a capacitor-bank-driven high voltage discharge to create a high pressure pulse that can be used to push material around at high speeds. In LIW, the pressure pulse is generated from short but powerful optical pulse and the launched metal piece is welded with another upon impact. With these techniques, speeds on the order of 1000 mph are achieved within a few microseconds in case of VFA and within a few nanoseconds in case of LIW. Such fast evolving speeds can be measured with high precision with the PDV technique which is central to our work. These developments have enabled indoor implementation of the types of experiments and processes that were previously only possible with explosives. In addition to process development for manufacturing applications, several avenues for fundamental research have been opened by this research effort, spall strength determination, shock Hugoniot estimation, shock induced phase transformation, twinning and hardening, and severe plastic deformation at high strain rate leading to dynamic recrystallization, to state a few. An example of severe plastic deformation at high strain rates can be seen in the image here from impact welding of large crystals of copper. Such work will be discussed along with an outlook for future research.

 

Bio

Anupam Vivek is a research scientist in the Department of Materials Science and Engineering at The Ohio State University. He received his B.Tech degree (2007) in manufacturing science from the Indian Institute of Technology, Kharagpur, and his MS (2010) and PhD (2012) degrees in materials science from Ohio State. He has held visiting researcher positions at the University of New Hampshire, the Technical University of Dortmund, Germany, and American Trim and serves on the Technology Advisory Committee of the International Impulse Forming Group. Anupam’s research interests lie in dynamic behavior of materials and their processing by electrically or optically generated impulse. He is a co-inventor of the Vaporizing Foil Actuator technology, which has grown into a field of its own since he wrote the first PhD thesis on it. He has co-authored over 49 journal articles and is an inventor on 8 patent filings.

Impulse Manufacturing Laboratory