FepiM: A Novel Inverse Piecewise Method to Determine Isothermal Flow Curves for Hot Working
In forming simulations, flow curves are cardinal inputs to predict features, such as forming forces and material flow. The laboratory-scale experiments to determine them, like compression or tensile tests, are affected by deformation heating, restricting direct flow curve determination. In principle...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-04-01
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| Series: | Metals |
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| Online Access: | https://www.mdpi.com/2075-4701/11/4/602 |
| _version_ | 1797538479438036992 |
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| author | Aditya Vuppala Alexander Krämer Johannes Lohmar Gerhard Hirt |
| author_facet | Aditya Vuppala Alexander Krämer Johannes Lohmar Gerhard Hirt |
| author_sort | Aditya Vuppala |
| collection | DOAJ |
| description | In forming simulations, flow curves are cardinal inputs to predict features, such as forming forces and material flow. The laboratory-scale experiments to determine them, like compression or tensile tests, are affected by deformation heating, restricting direct flow curve determination. In principle, the current analytical and inverse methods determine flow curves from these tests, but while the analytical methods assume a simplified temperature profile, the inverse methods require a closed-form flow curve equation, which mostly cannot capture complex material behavior like multiple recrystallization cycles. Therefore, the inverse piecewise flow curve determination method “FepiM” previously developed and published by the current authors is extended by introducing a two-step procedure to obtain isothermal flow curves at elevated temperatures and different strain rates. Thereby, the flow curve is represented as tabular data instead of an equation to reproduce complex flow curve shapes while also compensating the effect of inhomogeneous temperature profiles on the flow stress. First, a flow curve at the highest temperature is determined. In the second step, using this first flow curve as a reference, the flow curves at lower temperatures are obtained via interpolation. Flow curves from conventional compression tests for aluminum and copper in the temperature range of 20–500 °C are predicted, and it is shown that these flow curves can reproduce the experimental forces with a maximum deviation of less than 1%. Therefore, the proposed new piecewise method accurately predicts isothermal flow curves for compression tests, and the method could be further extended to highly inhomogeneous methods in the future. |
| first_indexed | 2024-03-10T12:32:00Z |
| format | Article |
| id | doaj.art-815a0848afe14aef96b00d4dd2d3d133 |
| institution | Directory Open Access Journal |
| issn | 2075-4701 |
| language | English |
| last_indexed | 2024-03-10T12:32:00Z |
| publishDate | 2021-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Metals |
| spelling | doaj.art-815a0848afe14aef96b00d4dd2d3d1332023-11-21T14:34:55ZengMDPI AGMetals2075-47012021-04-0111460210.3390/met11040602FepiM: A Novel Inverse Piecewise Method to Determine Isothermal Flow Curves for Hot WorkingAditya Vuppala0Alexander Krämer1Johannes Lohmar2Gerhard Hirt3Institute of Metal Forming, RWTH Aachen University, D-52062 Aachen, GermanyInstitute of Metal Forming, RWTH Aachen University, D-52062 Aachen, GermanyInstitute of Metal Forming, RWTH Aachen University, D-52062 Aachen, GermanyInstitute of Metal Forming, RWTH Aachen University, D-52062 Aachen, GermanyIn forming simulations, flow curves are cardinal inputs to predict features, such as forming forces and material flow. The laboratory-scale experiments to determine them, like compression or tensile tests, are affected by deformation heating, restricting direct flow curve determination. In principle, the current analytical and inverse methods determine flow curves from these tests, but while the analytical methods assume a simplified temperature profile, the inverse methods require a closed-form flow curve equation, which mostly cannot capture complex material behavior like multiple recrystallization cycles. Therefore, the inverse piecewise flow curve determination method “FepiM” previously developed and published by the current authors is extended by introducing a two-step procedure to obtain isothermal flow curves at elevated temperatures and different strain rates. Thereby, the flow curve is represented as tabular data instead of an equation to reproduce complex flow curve shapes while also compensating the effect of inhomogeneous temperature profiles on the flow stress. First, a flow curve at the highest temperature is determined. In the second step, using this first flow curve as a reference, the flow curves at lower temperatures are obtained via interpolation. Flow curves from conventional compression tests for aluminum and copper in the temperature range of 20–500 °C are predicted, and it is shown that these flow curves can reproduce the experimental forces with a maximum deviation of less than 1%. Therefore, the proposed new piecewise method accurately predicts isothermal flow curves for compression tests, and the method could be further extended to highly inhomogeneous methods in the future.https://www.mdpi.com/2075-4701/11/4/602flow curve determinationinverse modelingstress–strain curvecylindrical compression testsplastic deformationcopper ETP |
| spellingShingle | Aditya Vuppala Alexander Krämer Johannes Lohmar Gerhard Hirt FepiM: A Novel Inverse Piecewise Method to Determine Isothermal Flow Curves for Hot Working Metals flow curve determination inverse modeling stress–strain curve cylindrical compression tests plastic deformation copper ETP |
| title | FepiM: A Novel Inverse Piecewise Method to Determine Isothermal Flow Curves for Hot Working |
| title_full | FepiM: A Novel Inverse Piecewise Method to Determine Isothermal Flow Curves for Hot Working |
| title_fullStr | FepiM: A Novel Inverse Piecewise Method to Determine Isothermal Flow Curves for Hot Working |
| title_full_unstemmed | FepiM: A Novel Inverse Piecewise Method to Determine Isothermal Flow Curves for Hot Working |
| title_short | FepiM: A Novel Inverse Piecewise Method to Determine Isothermal Flow Curves for Hot Working |
| title_sort | fepim a novel inverse piecewise method to determine isothermal flow curves for hot working |
| topic | flow curve determination inverse modeling stress–strain curve cylindrical compression tests plastic deformation copper ETP |
| url | https://www.mdpi.com/2075-4701/11/4/602 |
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