Stress Analysis of the Bi-Metallic Coins – a Potential Shrink Fit Ring & Plug Standard

Stress Analysis of the Bi-Metallic Coins – a Potential Shrink Fit Ring & Plug Standard

S. Olsen, V. Luzin

Abstract. The “Shrink-fit ring and plug” system is known in the residual stress neutron community mostly due to the VAMAS Round Robin specimens, that were measured by most of the neutron residual stress instruments worldwide. This standard, however, can be challenging for some low flux instruments and considerable beamtime and efforts are required to accomplish measurements accordingly to the measurement protocol. Theoretically, the residual stress distribution is not simple, being neither plain stress nor plain strain, and essentially it is a 3D distribution with a large gradient toward the flat cut, especially for the axial component. Another “shrink-fit ring-and-plug” system is being considered, namely bi-metallic coins. With an easier zero plane stress state, they represent another potential candidate for a standard. Bi-metallic coins are in current circulation in many countries of the world. In the given study we report on an assessment of the residual stress state of 7 different bi-metallic coins measured by means of neutron diffraction to reconstruct the full stress state. The magnitudes of the stresses in the specimens were different obviously due to differences in the coinage process and materials in use. While in some cases residual stresses are weak and therefore difficult to measure accurately, in some cases stresses reach ~100 MPa. Although question in variability of the coinage process through years and within series is still debatable, tight standards and tolerances of the mint industry suggest the probability of consistency in the residual stress state making bi-metallic coin an interesting alternative to the VAMAS ring-and plug standard..

Keywords
Residual Stress, Neutron Diffraction, Bi-Metallic Coin

Published online 12/22/2016, 6 pages
Copyright © 2016 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA

Citation: S. Olsen, V. Luzin, ‘Stress Analysis of the Bi-Metallic Coins – a Potential Shrink Fit Ring & Plug Standard’, Materials Research Proceedings, Vol. 2, pp 31-36, 2017

DOI: https://dx.doi.org/10.21741/9781945291173-6

The article was published as article 6 of the book Residual Stresses 2016

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

References
[1] Webster, G. A., 2000, Neutron diffraction measurements of residual stress in a shrink-fit ring and plug VAMAS Report no. 38: National Physical Laboratory.
[2] Kirstein, O., Luzin, V., and Garbe, U., 2009, The Strain-Scanning Diffractometer Kowari: Neutron News, v. 20, no. 4, p. 34-36.
https://dx.doi.org/10.1080/10448630903241175