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Microcoining ripples in metal foils

Randall, Greg C. and Dahal, Jinesh and Vecchio, James and Agarwal, Shashank and Mehta, Rounak and Ravichandran, G. and Stebner, Aaron (2018) Microcoining ripples in metal foils. International Journal of Mechanical Sciences, 148 . pp. 263-271. ISSN 0020-7403 .

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Experiments, upper bound models, and finite element simulations are used to determine forming loads needed to microcoin surface ripples in thin metal foils. Coining is traditionally performed in a closed die, however enclosing all non-patterned surfaces is difficult to directly scale down to sub-millimeter foils. We find different forming regimes can exist at this small scale in an open pressing configuration. We explore the effects of the metal foil thickness and its work hardening behavior, two primary factors controlling the microcoining ripple forming load. For very thin foils, the load needed to coin a ripple pattern is lower than the load needed to compress the foil so that the open pressing configuration behavior is effectively closed with pattern formation without thickness change. For moderate thickness foils, the load needed to coin significantly drops as the entire foil compresses. For thick foils approaching bulk materials, the pattern will not completely form as the die macroscopically indents into the metal. Work hardening is found to raise the forming load for the thin, effectively closed die scenario, however it is a secondary effect at moderate thickness. This insight is used to microcoin patterns in extremely hard, thin metal foils.

Item Type:Article
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Randall, Greg C.0000-0002-8375-9041
Additional Information:© 2018 Elsevier Ltd. Received 26 May 2018, Revised 23 August 2018, Accepted 28 August 2018, Available online 29 August 2018.
Subject Keywords:Coining; plasticity; contact mechanics; indentation; work hardening
Record Number:CaltechAUTHORS:20180829-102418241
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Official Citation:Greg C. Randall, Jinesh Dahal, James Vecchio, Shashank Agarwal, Rounak Mehta, G. Ravichandran, Aaron P. Stebner, Microcoining ripples in metal foils, International Journal of Mechanical Sciences, Volume 148, 2018, Pages 263-271, ISSN 0020-7403, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89273
Deposited By: Tony Diaz
Deposited On:29 Aug 2018 17:40
Last Modified:14 Sep 2018 23:29

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