A Comparative Study on the Formability Prediction of Steel Sheets by Anisotropic Models Based on Associated Flow Rule and Non-Associated Flow Rule

2015 ◽  
Vol 651-653 ◽  
pp. 150-155 ◽  
Author(s):  
Jun He Lian ◽  
Deok Chan Ahn ◽  
Dong Chul Chae ◽  
Sebastian Münstermann ◽  
Wolfgang Bleck
Keyword(s):  
Comparative Study ◽  
Transverse Direction ◽  
Steel Sheet ◽  
Rolling Direction ◽  
Tensile Tests ◽  
Biaxial Stress ◽  
Flow Rule ◽  
Anisotropic Models ◽  
Formability Prediction ◽  
Associated Flow Rule

A comparative study on the formability prediction of a ferritic steel sheet by anisotropic models based on associated flow rule and non-associated rule is carried out. The uniaxial tensile tests along seven directions of the sheet from rolling direction to transverse direction with an interval of 15° are performed for the anisotropic yield stress and r-value. For the biaxial stress state, both bulge test and punch test are performed. The BBC2003 based on the associated flow rule is employed and its anisotropic parameters are calibrated to the yield stresses and r-values from the tensile tests along rolling direction, transverse direction and diagonal direction and the biaxial test. The non-associated quadratic Hill48 model is also calibrated to the same set of experimental data. Similar level of the predicative capability on the yield and plastic deformation directionality by the associated and non-associated based models is observed. With the common basis on the anisotropic plasticity characteristics, they are combined with the Marciniak–Kuczynski (MK) model to predict the formability of the steel sheet and distinct difference in the prediction is observed between the two models.

The Biaxial Stress-Strain Curves of Sheet Metals

2010 ◽  
Vol 44-47 ◽  
pp. 2519-2523
Author(s):  
Hai Bo Wang ◽  
Min Wan ◽  
Yu Yan ◽  
Xiang Dong Wu
Keyword(s):  
Transverse Direction ◽  
Biaxial Loading ◽  
Testing Machine ◽  
Rolling Direction ◽  
Biaxial Stress ◽  
Loading Path ◽  
Sheet Metals ◽  
Stress Strain ◽  
Loading Paths ◽  
Loading Ratio

Biaxial tensile tests of 5754O aluminum alloy sheet and B170P1 steel sheet were performed under linear loading paths with cruciform specimens and a biaxial loading testing machine. The stress-strain curves under different loading paths were obtained. It is found that the loading path has a significant influence on the stress-strain curves, i.e., the stress-strain curves vary with the loading path. The stress-strain curves in the rolling direction become higher with the decrease of the loading ratio (the ratio of the load along the rolling direction to that along the transverse direction) from 4:0 to 4:4. Meanwhile the stress-strain curves in the transverse direction become lower with the decrease of the loading ratio from 4:4 to 0:4. Based on Yld2000-2d yield criterion, the experimental phenomena of the two kinds of sheet metals under biaxial tension were explained theoretically.

Stresses in a Cr-Ni Superficial Steel Layer Based on X-Ray Measurements and Electropolishing

2014 ◽  
Vol 223 ◽  
pp. 355-361
Author(s):  
Barbara Kucharska ◽  
Michał Krzywiecki
Keyword(s):  
Transverse Direction ◽  
Steel Sheet ◽  
Rolling Direction ◽  
Stress Distributions ◽  
Rolled Steel ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
X Ray ◽  
Different Depths

Research of residual stresses in steel at different depths from its surface is presented in this paper. The material used for research was AISI 310S heat resistant steel (containing approx. 0.2%C, 25%Cr and 20%Ni) in form of a rolled steel sheet with a thickness of 2mm. Stress measurements were conducted with the use of KαCo radiation by the sin2ψ method in three directions, including the direction of the sheet's rolling (φ = 0°). For the purpose of measuring stresses at different depths from the surface, the steel underwent the process of electropolishing in electrolyte based on perchloric acid at 32 V for various durations (every 1-5 s) to the maximum depth of 35 μm. The set residual stress distributions vary depending on the direction of the test. The strongest stresses are on the steel's surface, and stresses have the widest range (from compressing to streching ones) in the area under the surface, which occurred in the rolling direction, and the narrowest range in its transverse direction. A correlation was discovered in the distribution of compression stresses and microhardness in the outer layer of the steel to a depth of 10 μm, where the role of plastic deformation in shaping the qualities of the steel outweighs the influence of structure content. This was proven using polar figures.

scholarly journals Microstructural Influence on Stretch Flangeability of Ferrite–Martensite Dual-Phase Steels

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1022
Author(s):  
Jae Hyung Kim ◽  
Taekyung Lee ◽  
Chong Soo Lee
Keyword(s):  
Mechanical Strength ◽  
Uniform Distribution ◽  
Transverse Direction ◽  
Rolling Direction ◽  
Expansion Ratio ◽  
Dual Phase ◽  
Normal Anisotropy ◽  
Hole Expansion Ratio ◽  
Dp Steels ◽  
Microstructural Effect

This work investigated the microstructural effect on stretch flangeability of ferrite–martensite dual-phase (DP) steels. Three types of DP steels with various martensitic structures were prepared for the research: fibrous martensite in water-quenched (WQ) sample, chained martensite in air-quenched (AQ) sample, and coarse martensite in step-quenched (SQ) sample. The WQ specimen exhibited the highest mechanical strength and hole expansion ratio compared to the AQ and SQ samples despite their similar fraction of martensite. Such a result was explained in view of uniform distribution of fine martensite and high density of geometrically necessary dislocations in the WQ specimen. Meanwhile, most cracks initiated at either rolling or transverse direction during the stretch flangeability test regardless of the martensitic morphology. It was attributed to the highest average normal anisotropy in the direction of 45° to rolling direction.

Transferability of the Gurson Damage Model Parameters with Charpy and Tensile Tests with Different Constrain Level

2009 ◽  
Vol 65 ◽  
pp. 19-31
Author(s):  
Ruben Cuamatzi-Melendez ◽  
J.R. Yates
Keyword(s):  
Strain Rate ◽  
Damage Model ◽  
Rolling Direction ◽  
Fracture Initiation ◽  
Tensile Tests ◽  
Model Parameters ◽  
Gurson Model ◽  
Finite Element Program ◽  
Element Program ◽  
Gurson's Model

Little work has been published concerning the transferability of Gurson’s ductile damage model parameters in specimens tested at different strain rates and in the rolling direction of a Grade A ship plate steel. In order to investigate the transferability of the damage model parameters of Gurson’s model, tensile specimens with different constraint level and impact Charpy specimens were simulated to investigate the effect of the strain rate on the damage model parameters of Gurson model. The simulations were performed with the finite element program ABAQUS Explicit [1]. ABAQUS Explicit is ideally suited for the solution of complex nonlinear dynamic and quasi–static problems [2], especially those involving impact and other highly discontinuous events. ABAQUS Explicit supports not only stress–displacement analyses but also fully coupled transient dynamic temperature, displacement, acoustic and coupled acoustic–structural analyses. This makes the program very suitable for modelling fracture initiation and propagation. In ABAQUS Explicit, the element deletion technique is provided, so the damaged or dead elements are removed from the analysis once the failure criterion is locally reached. This simulates crack growth through the microstructure. It was found that the variation of the strain rate affects slightly the value of the damage model parameters of Gurson model.

Gradient of Soil Constitutive Model

2010 ◽  
Vol 168-170 ◽  
pp. 1126-1129
Author(s):  
Wen Xu Ma ◽  
Ying Guang Fang
Keyword(s):  
Plastic Strain ◽  
Strain Gradient ◽  
Soil Analysis ◽  
Natural Material ◽  
Flow Rule ◽  
The Finite Element Method ◽  
Gradient Effect ◽  
Non Local ◽  
Associated Flow Rule ◽  
Plastic Strain Gradient

For the soil is a very complex natural material, significant strain gradient effect exist in soil analysis. Based on the "gradient" phenomenon, we add the plastic strain gradient hardening item into the traditional Cambridge yield surface. By using the consistency conditions and associated flow rule, we get the explicit expression of plastic strain gradient stiffness matrix. And the finite element method of plastic strain gradient is also shown in this article. Plastic strain gradient is actually a phenomenological non-local model containing microstructure information of the material. It may overcome the difficulties in simulating the gradient phenomenon by traditional mechanical model.

Characterisation of the plane anisotropy and its effect on interstitial free steel thin sheet metal forming simulation

2021 ◽  
pp. 146442072110534
Author(s):  
Latifa Arfaoui ◽  
Amel Samet ◽  
Amna Znaidi
Keyword(s):  
Thin Sheet ◽  
Rolling Direction ◽  
Tensile Tests ◽  
Interstitial Free ◽  
Experimental Database ◽  
Forming Simulation ◽  
Hardening Law ◽  
Tension Tests ◽  
Interstitial Free Steel ◽  
Thin Sheet Metal

The main purpose of this paper is to study the orthotropic plastic behaviour of the cold-rolled interstitial free steel HC260Y when it is submitted to various loading directions under monotonic tests. The experimental database included tensile tests carried out on specimens (in the as-received condition and after undergoing an annealing heat treatment) cut in different orientations according to the rolling direction. A model was proposed, depending on a plasticity criterion, a hardening law and an evolution law, which takes into account the anisotropy of the material. To validate the proposed identification strategy, a comparison with the experimental results of the planar tension tests, carried out on specimens cut parallel to the rolling direction, was considered. The obtained results allowed the prediction of the behaviour of this material when it is subjected to other solicitations whether simple or compound.

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