Research on Flow Stress Model Based on Strain Evolution

YUAN Jindong; MA Junqiang; CUI Xuexi; JIANG Sheng

doi:10.3969/j.issn.1674-6457.2026.04.022

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Journal of Netshape Forming Engineering ›› 2026, Vol. 18 ›› Issue (4) : 213-220. DOI: 10.3969/j.issn.1674-6457.2026.04.022

Advanced Manufacturing Technology and Equipment

Research on Flow Stress Model Based on Strain Evolution

YUAN Jindong¹, MA Junqiang², CUI Xuexi^2,*, JIANG Sheng¹

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Abstract

The work aims to study the strain hardening index evolution law, stress-strain relationship and plastic flow characteristics of aluminum alloys such as 2024 and 7A09, and to explore the flow stress model suitable for these materials, so as to provide better material model selection for these materials in part design, precision manufacturing and accurate finite element calculation. The evolution history of strain hardening indexes during the test was obtained by combining the single tension test with the theoretical formula of stress and strain, and the relationship between strain hardening indexes and strain variables was obtained. The stress-strain curves of 2024 and 7A09 aluminum alloys were established to verify the validity of the Hollomon-n flow stress model. By analyzing the test data, it was found that the n values of 2024 and 7A09 aluminum alloys were not fixed, but showed a nonlinear decreasing trend with the increase of strain. The n values decreased rapidly at small strain and slowly at large strain, and finally tended to be stable. Based on this, the Hollomon n flow stress model with variable n values could better describe the stress-strain relationship of the two aluminum alloys, and the error e_Hollomon-_n average values of the two aluminum alloys were lower than 5.4%, indicating that the flow stress model had high prediction accuracy. The n values of 2024 and 7A09 aluminum alloys are not constant in the deformation process, and the relationship between the n values and the dependent variables is in accordance with the power function. Hollomon-n flow stress model with variable n values can describe the stress-strain relationship of these two aluminum alloys well.

Key words

aluminum alloy / strain hardening index / flow stress model / non-contact measurement / unidirectional tensile test

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YUAN Jindong, MA Junqiang, CUI Xuexi, JIANG Sheng. Research on Flow Stress Model Based on Strain Evolution[J]. Journal of Netshape Forming Engineering. 2026, 18(4): 213-220 https://doi.org/10.3969/j.issn.1674-6457.2026.04.022

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