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A Finite Element Study of Thermo-Mechanical Fields and Their Relation to Friction Conditions in Al1050 Ring Compression Tests

Department of Materials Engineering, Nuclear Research Center—Negev (NRCN), Beer-Sheva 84190, Israel
Department of Mechanical Engineering—Center for thermo-mechanics and failure of materials (CTMFM), Shamoon College of Engineering, Beer-Sheva 84100, Israel
Rotem Industries—Ltd, Rotem Industrial park, Mishor Yemin 86800, Israel
Author to whom correspondence should be addressed.
J. Manuf. Mater. Process. 2018, 2(4), 83;
Received: 22 November 2018 / Revised: 13 December 2018 / Accepted: 14 December 2018 / Published: 17 December 2018
PDF [15102 KB, uploaded 17 December 2018]


The most accepted method for determining friction conditions in metal forming is the ring compression test (RCT). At high temperatures, extraction of the friction coefficient, μ, commonly requires numerical analysis due to the coupling between the mechanical and thermal fields. In the current study, compression tests of cylindrical specimens and RCT experiments were conducted on commercially pure aluminium (Al1050) at several temperatures, loading rates, and lubrication conditions. The experiments were used in conjunction with a coupled thermo-mechanical finite element analysis to study the dependence of the friction coefficient on those parameters. It is demonstrated that due to the coupling between friction conditions and material flow stress, both μ and flow stress data should be determined from the cylinder and ring specimens simultaneously and not subsequently. The computed friction conditions are validated using a novel method based on identification of the plastic flow neutral radius. It is shown that, due to heat loss mechanisms, the experimental system preparation stage must be incorporated in the computational analysis. The study also addresses the limitation of the RCT in the presence of high friction conditions. The computational models are finally used to examine the thermo-mechanical fields, which develop during the different processes, with an emphasis on the effect of friction conditions, which were then correlated to the resulting microstructure in the RCTs. View Full-Text
Keywords: compression; upsetting; RCT; friction; forming; Al1050; FE compression; upsetting; RCT; friction; forming; Al1050; FE

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Mittelman, B.; Priel, E.; Navi, N.U. A Finite Element Study of Thermo-Mechanical Fields and Their Relation to Friction Conditions in Al1050 Ring Compression Tests. J. Manuf. Mater. Process. 2018, 2, 83.

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