An Experimental-Numerical Combined Method to Determine the True Constitutive Relation of Tensile Specimens after Necking

Wang, You De; Xu, Shiyi; Ren, Song Bo; Wang, Hao

doi:10.1155/2016/6015752

Cited by 19 publications

(15 citation statements)

References 17 publications

(47 reference statements)

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“…Joun et al., 20 Zhao et al., 21 Kamaya and Kawakubo, 22 and Wang et al. 23 modified the flow stresses after necking point by point to enable the simulated load–displacement gradually approximate to the experimental curve. Majzoobi et al.…”

Section: Introductionmentioning

confidence: 99%

Inverse determination of the flow curve in large range of strains for cylindrical tensile specimen

Chen

Guan

Yang

2020

Proceedings of the Institution of Mechanical Engineers, Part C:

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In this study, an inverse method with the integration of finite element simulation and optimization algorithms is proposed to determine the flow curve of cylindrical specimen characterized by the modified Voce hardening model. The tensile test is repetitiously simulated with different combinations of model parameters designed through Latin hypercube design method, where the baseline values and variation ranges of model parameters are identified through Leroy–Bridgman method, obtaining different simulated load–displacement curves. The corresponding response is defined as the sum of the absolute area difference between the simulated load–displacement curves and the experimental one. The relationship between the model parameters and the response is established through response surface methodology and the optimal parameters combination in the modified Voce model is then determined through nonlinear programming by quadratic Lagrangian. In the case of uniaxial tensile test of mild steel Q345, the inversely identified flow curve is validated by numerically reproducing the experimental load–displacement curve and necking profile. The results indicate that the proposed inverse method is capable of evaluating the flow curve in large range of strains for cylindrical specimen accurately.

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Section: Introductionmentioning

confidence: 99%

Inverse determination of the flow curve in large range of strains for cylindrical tensile specimen

Chen

Guan

Yang

2020

Proceedings of the Institution of Mechanical Engineers, Part C:

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show abstract

“…Very recently, deformation behavior post-necking have been studied with greater interest. 15,30–36 Prediction of true stress-true strain curve beyond uniform deformation (after the onset of necking) is useful for studying large plastic deformation phenomena occurring during metal forming, crash, fatigue, and fracture. 35–37…”

Section: Introductionmentioning

confidence: 99%

A full-range stress-strain model for metallic materials depicting non-linear strain-hardening behavior

Swain¹,

Selvan²,

Thomas³

et al. 2020

The Journal of Strain Analysis for Engineering Design

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Ramberg-Osgood (R-O) type stress-strain models are commonly employed during elasto-plastic analysis of metals. Recently, 2-stage and 3-stage R-O variant models have been proposed to replicate stress-strain behavior under large plastic deformation. The complexity of these models increases with the addition of each stage. Moreover, these models have considered deformation till necking only. In this paper, a simplistic multi-stage constitutive model is proposed to capture the strain-hardening non-linearity shown by metals including its post necking behavior. The constitutive parameters of the proposed stress-strain model can be determined using only elastic modulus and yield strength. 3-D digital image correlation was used as an experimental tool for measuring full-field strains on the specimens, which were subsequently utilized to obtain the material parameters. Our constitutive model is demonstrated with an aerospace-grade stainless steel AISI 321 wherein deformation response averaged over the gauge length (GL) and at a local necking zone are compared. The resulting averaged and local material parameters obtained from the proposed model provide interesting insights into the pre and post necking deformation behavior. Our constitutive model would be useful for characterizing highly ductile metals which may or may not depict non-linear strain hardening behavior including their post necking deformations.

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“…The inverse analysis has been applied to calculate the true stress-strain curves after necking [17][18][19] or identify the parameters in constitutive models of materials. [20][21][22] Although the inverse methods have an excellent capability of determining the post-necking hardening curve, their poor efficiency due to an enormous amount of iterative calculation leads to less application as compared with the analytical models or the extrapolation methods. With the development of optical technology such as digital image correlation (DIC), the geometrical parameters of tensile neck can be characterized more conveniently.…”

Section: Introductionmentioning

confidence: 99%

The improvement of stress correction in post-necking tension of cylindrical specimen

Chen

Guan

et al. 2019

The Journal of Strain Analysis for Engineering Design

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In post-necking tension of cylindrical specimen, the stress corrections based on the current analytical models have relatively significant errors at large strains. In this study, the prediction capability of these models involving Bridgman model, Siebel model and Chen model is evaluated by performing a series of finite element simulations of uniaxial tension of cylindrical specimen with different hardening exponents varied from 0.05 to 0.3. Numerical analysis of stress and strain distributions on the necking cross section indicates that the considerable errors of the corrected stresses corresponding to large strains might be mainly attributed to the assumption of uniform strain distribution on the necking cross section in these analytical models. The modification strategies of these models are presented in order to improve their prediction accuracy of post-necking stresses, taking geometrical configuration of neck and material properties into consideration. Accordingly, the modification formulas are proposed based on simulation results, involving the radius of cross section of neck and the hardening exponent. Finally, these formulas are used to correct the stresses in the post-necking tension of Q345 cylindrical specimen, which are compared with the stresses identified through inverse method. The results indicate that the modified models significantly improve the prediction accuracy of post-necking stresses at large strains.

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An Experimental-Numerical Combined Method to Determine the True Constitutive Relation of Tensile Specimens after Necking

Cited by 19 publications

References 17 publications

Inverse determination of the flow curve in large range of strains for cylindrical tensile specimen

Inverse determination of the flow curve in large range of strains for cylindrical tensile specimen

A full-range stress-strain model for metallic materials depicting non-linear strain-hardening behavior

The improvement of stress correction in post-necking tension of cylindrical specimen

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