An Inverse Piecewise Flow Curve Determination Method for Torsion Tests at Elevated Temperature
This paper presents an extended method for determining flow curves under shear loading using torsion tests, a technique often used to characterize plastic behavior in metal forming. Torsion tests are advantageous due to their ability to achieve flow curves up to large strains (~3) while maintaining...
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MDPI AG
2025-02-01
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| author | Aditya Vuppala Holger Brüggemann David Bailly Emad Scharifi |
| author_facet | Aditya Vuppala Holger Brüggemann David Bailly Emad Scharifi |
| author_sort | Aditya Vuppala |
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| description | This paper presents an extended method for determining flow curves under shear loading using torsion tests, a technique often used to characterize plastic behavior in metal forming. Torsion tests are advantageous due to their ability to achieve flow curves up to large strains (~3) while maintaining stable specimen geometry during deformation. However, the strain and strain rate distribution across the specimen are non-uniform, increasing radially from the rotation axis. Traditional analytical methods, such as the Fields and Backofen approach, address this non-uniformity by considering average strain and strain rates. Conversely, inverse approaches, which rely on fitting constitutive equations through iterative procedures, are more sensitive to the choice of empirical equations and can be computationally expensive. To address these issues, this study adapts an inverse piecewise flow curve determination method from compression tests for use in torsion tests. A stepwise methodology is proposed to calculate constant strain rates and isothermal flow curves, where flow curves for the lowest strain rates are first determined and subsequently used to derive flow curves at higher strain rates. The proposed approach was applied to the case-hardened steel 16MnCrS5, with tests conducted at temperatures ranging from 900 °C to 1100 °C and strain rates from 0.01 s<sup>−1</sup> to 1 s<sup>−1</sup>. The experimental data obtained were successfully replicated by the flow curves with a maximum deviation of only 1%. The results demonstrate the efficiency and accuracy of the stepwise inverse approach for determining flow curves in torsion tests, making it appropriate for characterizing material behavior for metal-forming applications. |
| format | Article |
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| language | English |
| publishDate | 2025-02-01 |
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| spelling | doaj-art-07991d0e49ab4c708b722873fbe762b22025-08-20T02:44:42ZengMDPI AGMetals2075-47012025-02-0115221910.3390/met15020219An Inverse Piecewise Flow Curve Determination Method for Torsion Tests at Elevated TemperatureAditya Vuppala0Holger Brüggemann1David Bailly2Emad Scharifi3Institute of Metal Forming, RWTH Aachen University, Intzestraße 10, 52072 Aachen, GermanyInstitute of Metal Forming, RWTH Aachen University, Intzestraße 10, 52072 Aachen, GermanyInstitute of Metal Forming, RWTH Aachen University, Intzestraße 10, 52072 Aachen, GermanyInstitute of Metal Forming, RWTH Aachen University, Intzestraße 10, 52072 Aachen, GermanyThis paper presents an extended method for determining flow curves under shear loading using torsion tests, a technique often used to characterize plastic behavior in metal forming. Torsion tests are advantageous due to their ability to achieve flow curves up to large strains (~3) while maintaining stable specimen geometry during deformation. However, the strain and strain rate distribution across the specimen are non-uniform, increasing radially from the rotation axis. Traditional analytical methods, such as the Fields and Backofen approach, address this non-uniformity by considering average strain and strain rates. Conversely, inverse approaches, which rely on fitting constitutive equations through iterative procedures, are more sensitive to the choice of empirical equations and can be computationally expensive. To address these issues, this study adapts an inverse piecewise flow curve determination method from compression tests for use in torsion tests. A stepwise methodology is proposed to calculate constant strain rates and isothermal flow curves, where flow curves for the lowest strain rates are first determined and subsequently used to derive flow curves at higher strain rates. The proposed approach was applied to the case-hardened steel 16MnCrS5, with tests conducted at temperatures ranging from 900 °C to 1100 °C and strain rates from 0.01 s<sup>−1</sup> to 1 s<sup>−1</sup>. The experimental data obtained were successfully replicated by the flow curves with a maximum deviation of only 1%. The results demonstrate the efficiency and accuracy of the stepwise inverse approach for determining flow curves in torsion tests, making it appropriate for characterizing material behavior for metal-forming applications.https://www.mdpi.com/2075-4701/15/2/219flow curve determinationtorsion testsinverse modelingplastic deformation |
| spellingShingle | Aditya Vuppala Holger Brüggemann David Bailly Emad Scharifi An Inverse Piecewise Flow Curve Determination Method for Torsion Tests at Elevated Temperature Metals flow curve determination torsion tests inverse modeling plastic deformation |
| title | An Inverse Piecewise Flow Curve Determination Method for Torsion Tests at Elevated Temperature |
| title_full | An Inverse Piecewise Flow Curve Determination Method for Torsion Tests at Elevated Temperature |
| title_fullStr | An Inverse Piecewise Flow Curve Determination Method for Torsion Tests at Elevated Temperature |
| title_full_unstemmed | An Inverse Piecewise Flow Curve Determination Method for Torsion Tests at Elevated Temperature |
| title_short | An Inverse Piecewise Flow Curve Determination Method for Torsion Tests at Elevated Temperature |
| title_sort | inverse piecewise flow curve determination method for torsion tests at elevated temperature |
| topic | flow curve determination torsion tests inverse modeling plastic deformation |
| url | https://www.mdpi.com/2075-4701/15/2/219 |
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