Experimental evaluation and constitutive modeling of non-proportional deformation for asymmetric steels

Verma, Rahul Kumar; Kuwabara, Toshihiko; Chung, Kwansoo; Haldar, Arunansu

doi:10.1016/j.ijplas.2010.04.002

Cited by 95 publications

(63 citation statements)

References 59 publications

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“…In this study, three theoretical yield functions (von Mises, r-Hill [6], and Varma [5]) were determined. Verma's yield function is defined as; Anisotropic parameters of this function can be explicitly determined using the uniaxial tensile test data in 3 directions, compression test data in 2 directions and bi-axial tensile test data.…”

Section: Resultsmentioning

confidence: 99%

“…Verma's yield function is defined as; Anisotropic parameters of this function can be explicitly determined using the uniaxial tensile test data in 3 directions, compression test data in 2 directions and bi-axial tensile test data. Parameter identification method is shown in literature [5]. Using Verma's model, the SD effect was successfully reproduced.…”

Section: Resultsmentioning

confidence: 99%

“…Some authors proposed asymmetric yield function to reproduce the SD effect [4], [5]. However those models are not used in press forming simulation practically.…”

Section: Introductionmentioning

confidence: 99%

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High accuracy springback simulation by using material model considering the SD effect

Noma¹,

Hashimoto²,

Maeda

et al. 2018

J. Phys.: Conf. Ser.

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Abstract. In order to enhance the accuracy of springback simulation, the strength differential (SD) effect, i.e., the difference in flow stress between tension and compression, of a high strength cold-rolled steel sheet with a tensile strength of 980 MPa is measured by means of inplane tension-compression test apparatus. Bi-axial stress tests are also performed to measure the contour of plastic work of the test material. From those experimental results, the material model which can consider the SD effect is determined. Furthermore, this material model is implemented into commercial FEM code by using user-subroutine function. To check the validity of this model and established FEM analysis system, curvature-hat crush forming experiment is performed. By comparing the experimental result and forming simulation result, the accuracy of the material model which can consider the SD effect is validated. Consequently it is concluded that the use of material model which is capable of reproducing the SD effect is a must to enhance the accuracy of springback simulation.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

High accuracy springback simulation by using material model considering the SD effect

Noma¹,

Hashimoto²,

Maeda

et al. 2018

J. Phys.: Conf. Ser.

Self Cite

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“…However, for predicting such defects accurately, it is required to characterize the deformation behavior, especially under non-monotonous/non-proportional deformation conditions, and to develop constitutive equations suitable for describing observed deformation behaviors. [1][2][3] It is increasingly agreed in the research community working on sheet forming that experimentation and modeling under non-monotonous/non-proportional deformation conditions are important for accuracy in forming simulations and in the performance prediction of sheet products. Researchers have performed experiments using many different strain paths and evaluated the deformation behavior under such conditions.…”

Section: Introductionmentioning

confidence: 99%

“…The model based on combined isotropic-kinematic hardening with permanent softening 1) was utilized to simulate the deformation behavior under such deformation conditions and it was found that the above model was capable of correctly predicting the deformations for both cases considered here. It was also noticed that the incorporation of permanent softening often observed during reverse loading, is important for accurately predicting the deformation when bending-unbending (or strain reversals) takes place.KEY WORDS: non-proportional; 2D draw bend; permanent softening; combined isotropic-kinematic hardening.experiments on an ultra low carbon steel, for different combinations of cross tests and tension-compression tests and also proposed modifications to the combined hardening model of Chung et al 1,28) It was observed for this particular steel that, during the cross test, the hardening curve finally converges to the original monotonic curve suggesting that the isotropic hardening might be good enough (excepting the cross effect observed initially before converging to the original curve) to model the hardening behavior during cross tests. However, it was not clear, whether the hardening curve will saturate to the original monotonic curve even for more complex strain paths.…”

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confidence: 99%

Effect of Pre-strain on Anisotropic Hardening and Springback Behavior of an Ultra Low Carbon Automotive Steel

2011

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Modeling non-monotonous and/or non-proportional deformation is challenging partly because of lack of constitutive equations and more so because of unavailability of sufficient experimental data. In the present work, two different experiments involving non-monotonous/non-proportional deformation have been proposed. The model based on combined isotropic-kinematic hardening with permanent softening 1) was utilized to simulate the deformation behavior under such deformation conditions and it was found that the above model was capable of correctly predicting the deformations for both cases considered here. It was also noticed that the incorporation of permanent softening often observed during reverse loading, is important for accurately predicting the deformation when bending-unbending (or strain reversals) takes place.KEY WORDS: non-proportional; 2D draw bend; permanent softening; combined isotropic-kinematic hardening.experiments on an ultra low carbon steel, for different combinations of cross tests and tension-compression tests and also proposed modifications to the combined hardening model of Chung et al. 1,28) It was observed for this particular steel that, during the cross test, the hardening curve finally converges to the original monotonic curve suggesting that the isotropic hardening might be good enough (excepting the cross effect observed initially before converging to the original curve) to model the hardening behavior during cross tests. However, it was not clear, whether the hardening curve will saturate to the original monotonic curve even for more complex strain paths. They also observed a significant amount of permanent softening during reverse loading and suggested that the softening behavior is not only incurred by the translation of the yield surface but also by the shrinkage of the yield surface size. They consequently proposed a method to incorporate both of these in the constitutive model.In the present work, two new two-stage experiments under non-monotonous/non-proportional deformation conditions were performed for the same ultra law carbon steel used by Verma et al. 1) : 2D draw bending of a pre-strained sample and uni-axial simple tension with a specimen prepared from the wall portion of a 2D draw-bent component. Simulations were performed using the material model proposed by Verma et al. 1) for these experiments and it was found that the model was capable of successfully representing the deformation even for such complex deformation paths for this steel grade. Experimental ProcedureThe material selected for this study was the same cold rolled, annealed and skin passed interstitial free high strength (IFHS) steel with 1.0 mm thickness, which was used by Verma et al. and the tensile properties of which is given in Table 1. 1) In this study, 2D draw bending experiments were performed for two different cases: the one with samples prepared from the base material without any pre strains and the second with specimens prepared on samples which were already pre-strained by 5% (nominal strain)....

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Microstructures and Mechanical Properties of a Commercial Pure Zirconium during Rolling and Annealing at Different Temperatures

Chen

et al. 2020

Adv Eng Mater

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Zirconium (Zr) alloys have been widely applied in nuclear reactors due to their low probability of neutron capture, acceptable mechanical properties, and excellent corrosion resistance. [1-6] Zirconium alloys are commonly used as cladding tubes, fixed grids, or channel box in reactors. [2,3,6] The fabrication of Zr alloys components generally includes vacuum consumable melting, forging, extrusion, hot and cold rolling, recrystallization or stress relief annealing and so on. [7] Rolling and subsequent annealing are frequently used in the Zr alloy sheet and tube production, which actually determine the microstructure and texture, [7-10] thus playing a decisive role for the corrosion resistance, [11-14] creep resistance [15-17] and mechanical properties [18-20] of Zr alloys. Annealing can reduce the residual stress, recover the plastic deformation ability and tailor the grain size and texture, which plays a vital role in the Zr alloy fabrication. A special parameter was thus proposed to evaluate the effect of annealing. [21] The microstructure and the texture evolution during annealing are not only significantly affected by annealing condition, for example temperature [22,23] and holding time, [8,24] but also by the pre-annealing deformation. [6,25] Indeed, many research results on deformation and subsequent annealing in Zr alloys have been reported. Chen et al. [7] reported that the 30% rolling reduction combined with annealing at 580 C for 12 h imparted a superior plasticity to the Zr alloy. Kumara et al. [26] investigated the three stage of annealing in a moderately deformed Zr-4 alloy. They found that the changes in the misorientations, and corresponding rearrangements of dislocations, were the most efficient means of stress relief in Zr-4 alloy. Prakash et al. [27] investigated the microstructural and textural evolution of ZIRLO alloy during hot rolling at different temperatures. Their results show that the slip, twinning, and recrystallization played a role in the microstructure development during hot rolling. They also contributed to the texture development, lamellae break-up, and the formation of a bimodal microstructure. Jiang et al. [28] studied the effects of cold-rolling reduction, annealing temperature, and time on recrystallization behavior and kinetics of cold-rolled Zr-1Sn-0.3Nb-0.3Fe-0.1Cr alloy and found that the rate of the recrystallization increased with increasing annealing temperature and rolling reduction. Recrystallized grains nucleated preferentially at sites with high-density dislocation and deformation stored energy. Zhang et al. [29] studied the microstructure evolution and mechanical properties of Zr 98.2 Cr 1.8 during hot rolling, solution and aging treatment (STA). It was found the bimodal microstructure was the key factor to achieve high strength (ultimate tensile strength 818 MPa) and excellent ductility (18.4%) after STA at 750 C. Gerspach et al. [30] investigated the texture stability during primary recrystallization of cold-rolled Zr702 alloy and found that a small strain favored...

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Experimental evaluation and constitutive modeling of non-proportional deformation for asymmetric steels

Cited by 95 publications

References 59 publications

High accuracy springback simulation by using material model considering the SD effect

High accuracy springback simulation by using material model considering the SD effect

Effect of Pre-strain on Anisotropic Hardening and Springback Behavior of an Ultra Low Carbon Automotive Steel

Microstructures and Mechanical Properties of a Commercial Pure Zirconium during Rolling and Annealing at Different Temperatures

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