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A Study on Material Workability by Upsetting of Non-Axisymmetric Specimens by Flat Dies

Published online by Cambridge University Press:  21 October 2014

S. Alexandrov ,
M. Vilotic ,
Y.-R. Jeng  and
M. Plancak
S. Alexandrov
Affiliation:
A. Ishlinskii Institute for Problems in Mechanics, Russian Academy of Sciences, Moscow, Russia Department of Mechanical Engineering and Advanced Institute of Manufacturing with High-Tech Innovations, National Chung Cheng University, Chiayi, Taiwan
M. Vilotic*
Affiliation:
Department of Mechanical Engineering and Advanced Institute of Manufacturing with High-Tech Innovations, National Chung Cheng University, Chiayi, Taiwan Faculty of Technical Sciences, University of Novi Sad, Novi Sad, Serbia
Y.-R. Jeng
Affiliation:
Department of Mechanical Engineering and Advanced Institute of Manufacturing with High-Tech Innovations, National Chung Cheng University, Chiayi, Taiwan
M. Plancak
Affiliation:
Faculty of Technical Sciences, University of Novi Sad, Novi Sad, Serbia
*
*markovil@uns.ac.rs
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Abstract

Upsetting is a typical test for determining the workability diagram. In most cases axisymmetric samples are used for such tests. However, the shape of samples may have a significant effect on the ductile fracture initiation. Therefore, a greater variety of sample geometry should lead to a more accurate shape of the workability diagram. A difficulty here is that a theoretical treatment of samples in which three-dimensional flow occurs is more difficult and time consuming as compared to axisymmetric samples under axisymmetric loading. This difficulty can be overcome in the case of the ductile fracture criterion based on the workability diagram and the average value of the triaxiality factor. In particular, if fracture occurs at free surfaces then it is sufficient to determine experimentally in-surface strains after several stages of the upsetting process, up to the initiation of ductile fracture. After that, the corresponding point of the workability diagram can be found by means of a simple analytical procedure and numerical integration. This approach is used in the present paper to correct the workability diagram using non-axisymmetric upsetting of five different samples made of steel. Some previous results are combined with the new results to obtain the workability diagram over a wide range of the triaxiality factor.

Keywords

UpsettingDuctile fractureExperimental-analytical method
Type
Research Article
Information
Journal of Mechanics , Volume 30 , Issue 6 , December 2014 , pp. 585 - 592
Copyright
Copyright © The Society of Theoretical and Applied Mechanics, R.O.C. 2014 

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References

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