Study of Aluminum Alloy 7050 T7451 Isotropic Hardening

2016 ◽  
Vol 869 ◽  
pp. 526-531
Author(s):  
Rodrigo Mendes Lima ◽  
Ernesto Massaroppi Jr.
Keyword(s):  
Aluminum Alloy ◽  
Stress State ◽  
Bauschinger Effect ◽  
Kinematic Hardening ◽  
Isotropic Hardening ◽  
Compression Tests ◽  
Plastic Deformations ◽  
Fem Simulations ◽  
Nonlinear Constitutive Model ◽  
Cyclic Tension

This paper presents the yielding surface isotropic hardening study of the aluminum alloy 7050 T7451 submitted to monotonic loadings, considering the nonlinear constitutive model proposed by Voce. The stress state imposed characterizes a behavior whose plastic deformations cannot be neglected. The analysis depends on the segregation between the isotropic and the kinematic hardening that composes the material’s behavior during its transient life. Monotonic and cyclic tension-compression tests have been realized in order to allow the Bauschinger Effect understanding. The results have been compared to FEM simulations in order to validate the model.

Springback of Copper Alloy Sheets after U-Bending

2014 ◽  
Vol 510 ◽  
pp. 118-122 ◽  
Author(s):  
Hiroshi Hamasaki ◽  
Yasuhiro Hattori ◽  
Kingo Furukawa ◽  
Fusahito Yoshida
Keyword(s):  
Copper Alloy ◽  
Bauschinger Effect ◽  
Kinematic Hardening ◽  
Alloy Sheet ◽  
Isotropic Hardening ◽  
Hardening Model ◽  
Cyclic Tension ◽  
Cold Rolled ◽  
Simulation Results ◽  
Strain Responses

Springback after U-bending of Cu-Ni-Si alloy sheet and cold-rolled brass sheets (JIS C2600R-H and C2600R-1/4H) was calculated by using FEM. In the simulations, the Yoshida-Uemori kinematic hardening model was employed, by which stress-strain responses under uniaxial tension and cyclic tension-compression loadings are accurately described. The simulation results using Yoshida-Uemori model well predicted the experimentally obtained springback, while the isotropic hardening model underestimated it for every material. From such comparisons between experiment and simulation, it is concluded that the Bauschinger effect as well as the plastic strain dependency on Youngs modulus should be taken into account for an accurate springback simulation.

Bauschinger Effect Investigation of an Aluminum Alloy, and Its Application in Autofrettaged and Compound Tubes

2007 ◽  
Author(s):  
M. Mohammadi ◽  
G. H. Farrahi ◽  
S. H. Hoseini
Keyword(s):  
Aluminum Alloy ◽  
Residual Stresses ◽  
Bauschinger Effect ◽  
Testing Machine ◽  
Isotropic Hardening ◽  
Compression Tests ◽  
Effect Factor ◽  
Hardening Rule ◽  
Instron Testing Machine ◽  
Shrink Fit

For characterizing Bauschinger effect factor (BEF) and Bauschinger modulus reduction of an A5083 aluminum alloy experimentally, several uniaxial tension-compression tests carried out in different pre-strain levels using INSTRON testing machine. BEF was investigated using both Welter and Milligan’s definitions for various offset values. It was observed that Milligan’s definition predicts BEF less than Welter’s definition for all offset values. In addition, real loading-unloading behavior of such alloy was recorded to predict residual stresses resulting from autofrettage and shrink fit processes. Variable material properties (VMP) method, which is capable of incorporating real unloading behavior of materials, was used as an accurate way to estimate residual stresses. Hoop residual stresses were calculated using real unloading behavior and isotropic hardening rule. Results showed that, isotropic hardening rule in comparison with real unloading behavior overestimates bore hoop residual stresses up to 12%.

Predictions of microtorsional experiments by micropolar plasticity

2005 ◽  
Vol 461 (2053) ◽  
pp. 189-205 ◽  
Author(s):  
Paschalis Grammenoudis ◽  
Charalampos Tsakmakis
Keyword(s):  
Size Effects ◽  
Bauschinger Effect ◽  
Kinematic Hardening ◽  
Circular Cylinders ◽  
Isotropic Hardening ◽  
Gradient Plasticity ◽  
Material Response ◽  
Micropolar Plasticity ◽  
Classical Plasticity ◽  
Hardening Rules

Kinematic hardening rules are employed in classical plasticity to capture the so–called Bauschinger effect. They are important when describing the material response during reloading. In the framework of thermodynamically consistent gradient plasticity theories, kinematic hardening effects were first incorporated into a micropolar plasticity model by Grammenoudis and Tsakmakis. The aim of the present paper is to investigate this model by predicting size effects in torsional loading of circular cylinders. It is shown that kinematic hardening rules compared with isotropic hardening rules, as adopted in the paper, provide more possibilities for modelling size effects in the material response, even if only monotonous loading conditions are considered.

On Simulation of Bend/Reverse Bend of Sheet Metals

1999 ◽  
Author(s):  
K. M. Zhao ◽  
J. K. Lee
Keyword(s):  
Bauschinger Effect ◽  
Kinematic Hardening ◽  
High Strength ◽  
Isotropic Hardening ◽  
Sheet Metals ◽  
Combined Model ◽  
Hardening Law ◽  
Three Point Bend Test ◽  
Point Bend ◽  
Plastic Shakedown

Abstract Bend/reverse bend tests are performed with a three-point bend test apparatus on two types of sheet metals, mild steel and high strength steel. The bend/reverse bend process tends to a steady cycle upon applying repeated cycles of displacements. Strain hardening and Bauschinger effects for both materials are detected. Three different hardening laws are used to simulate the bend process numerically. Isotropic hardening law overestimates the hardening component and by missing the Bauschinger effect and the plastic shakedown. Kinematic hardening rule underestimates the hardening component and exaggerates the Bauschinger effect. The combination of isotropic and nonlinear kinematic hardening predicts accurately both the Bauschinger effect and the plastic shakedown. The hardening parameters in the combined model are identified inversely by using micro genetic algorithm.

Identification of the anisotropic behavior of an aluminum alloy subjected to simple and cyclic shear tests

2018 ◽  
Vol 233 (3) ◽  
pp. 911-927 ◽  
Author(s):  
Daghfas Olfa ◽  
Znaidi Amna ◽  
Gahbiche Amen ◽  
Nasri Rachid
Keyword(s):  
Aluminum Alloy ◽  
Kinematic Hardening ◽  
Plastic Anisotropy ◽  
Mechanical Tests ◽  
Material Behavior ◽  
Isotropic Hardening ◽  
Cyclic Tests ◽  
Shear Tests ◽  
2024 Aluminum Alloy ◽  
Cyclic Shear

The main purpose of this paper is to study the behavior of the 2000 aluminum alloy series used particularly in the design of Airbus fuselage. The characterization of the mechanical behavior of sheet metal on 2024 aluminum alloy and its response to various loading directions under monotonic and cyclic tests are extremely considered. To solve this problem, first, an experimental platform which essentially revolves around mechanical tests and then a series of optical and transmission electronic visualizations have been carried out. These mechanical tests are monotonic and cyclic shear tests applied under the same conditions on the test specimens of 2024 aluminum alloy. Cyclic shear tests have been carried out in order to show the Bauschinger effect and then the kinematic hardening phenomenon. The hardening curves of the simple shear test showed the Portevin-Le Chatelier effect for all loading directions. Next, the experimental results obtained (Portevin-Le Chatelier and Bauschinger effects) are discussed and analyzed in relation to the microstructure of the studied alloy using an optical microscope and a transmission electron microscope. Thereafter, the plastic anisotropy is modeled using an identification strategy that depends on a plastic criterion, an isotropic hardening law, a kinematic hardening (linear and nonlinear) law, and an evolution law. More precisely, particular attention is paid to the isotropic power Hollomon law, the saturation Voce law, and the saturation Bron law. In the case of the cyclic tests, linear kinematic hardening described by the Prager law and nonlinear kinematic hardening expressed by the Armstrong–Frederick law are introduced. Finally, by smoothing the experimental hardening curves for the various simple and cyclic shear tests, a selection is made in order to choose the most appropriate law for the identification of the material behavior.

Effects of Hardening Models on CUO Forming and Springback Simulation of High Strength Line Pipes

2015 ◽  
Vol 817 ◽  
pp. 8-13 ◽  
Author(s):  
Qiang Ren ◽  
Tian Xia Zou ◽  
Da Yong Li
Keyword(s):  
Bauschinger Effect ◽  
Oil And Gas ◽  
Kinematic Hardening ◽  
High Strength ◽  
Isotropic Hardening ◽  
Forming Process ◽  
Hardening Model ◽  
Hardening Models ◽  
Combined Hardening ◽  
Springback Prediction

The UOE process is an effective approach for manufacturing the line pipes used in oil and gas transportation. During the UOE process, a steel plate is crimped along its edges, pressed into a circular pipe with an open-seam by the successively U-O forming stages. Subsequently, the open-seam is closed and welded. Finally, the welded pipe is expanded to obtain a perfectly round shape. In particular, during the O-forming stage the plate is suffered from distinct strain reversal which leads to the Bauschinger effect, i.e., a reduced yield stress at the start of reverse loading following forward strain. In the finite element simulation of plate forming, the material hardening model plays an important role in the springback prediction. In this study, the mechanical properties of API X90 grade steel are obtained by a tension-compression test. Three popular hardening models (isotropic hardening, kinematic hardening and combined hardening) are employed to simulate the CUO forming process. A deep analysis on the deformation and springback behaviors of the plate in each forming stage is implemented. The formed configurations from C-forming to U-forming are almost identical with three hardening models due to the similar forward hardening behaviors. Since the isotropic hardening model cannot represent the Bauschinger effect, it evaluates the higher reverse stress and springback in the O-forming stage which leads to a failure prediction of a zero open-seam pipe. On the contrary, the kinematic hardening model overestimates the Bauschinger effect so that predicts the larger open-seam value. Specifically, the simulation results using the combined hardening model show good agreement in geometric configurations with the practical measurements.

Single sample method for assessing the Baushinger effect

2020 ◽  
Vol 86 (7) ◽  
pp. 55-58
Author(s):  
A. D. Khvan ◽  
D. V. Khvan ◽  
A. A. Voropaev
Keyword(s):  
Plastic Deformation ◽  
Stress State ◽  
Yield Strength ◽  
Bauschinger Effect ◽  
Calculated Data ◽  
Compressive Yield Strength ◽  
Special Device ◽  
Compression Tests ◽  
Traditional Procedure

The Bauschinger effect is one of the fundamental properties of most metal alloys exposed to plastic deformation under non-monotonic loading. Development of the methods for quantifying this effect is one the important issues of the theory of plasticity. Calculation of the parameter characterizing the aforementioned effect is required for determination of the stress state in plastically deformable blanks upon pressure metal treatment. The value of the parameter (determined in standard tensile tests followed by subsequent compression of samples) is defined by the ratio of the conditional yield strength of the sample under compression to the value of the preliminary tensile stress. A series of cylindrical samples (~10 pcs.) is usually taken for tensile-compression tests. According to the traditional procedure, long-size standard specimens are pre-stretched to various degrees of plastic deformation. After that short specimens are cut out from those specimens for compression tests to determine the conditional compressive yield strength with a tolerance of 0.2% for plastic deformation. Such a procedure is rather time consuming and expensive. We propose and develop a new single-model method for estimating the Bauschinger effect which consists in testing of a single long-size specimen for tension followed by compression of the specimen in a special device providing deformation of a previously stretched specimen without flexure under conditions of a linear stress state. The device was designed, manufactured and underwent the appropriate tests. The device contains supporting elements in the form of conical-shaped sectors that prevent flexure of a long cylindrical specimen upon compression, a ratio of the working part length to diameter ranges from 5 to 10. The results of experimental determination of the parameter β characterizing the indicated effect are presented. The results of comparing the values of the parameter β determined by the developed and traditional methods revealed the possibility of determining the parameter β using the proposed method. To reduce the complexity of performing tests related to determination of the parameter β we approximated it in the form of an exponent as a function of the magnitude of plastic deformation and determine the only one value of β0 under plastic deformations exceeding 0.05. In this regard, β0 can be considered a new characteristic of the material. The calculated data are in good agreement with the experimental results. The values of β0 are determined for a number of studied steel grades.

Uniaxial Ratchetting of 316FR Steel at Room Temperature— Part I: Experiments

1999 ◽  
Vol 122 (1) ◽  
pp. 29-34 ◽  
Author(s):  
M. Mizuno ◽  
Y. Mima ◽  
M. Abdel-Karim ◽  
N. Ohno
Keyword(s):  
Plastic Strain ◽  
Room Temperature ◽  
Kinematic Hardening ◽  
Hysteresis Loops ◽  
Strain Range ◽  
Cyclic Hardening ◽  
Isotropic Hardening ◽  
Cyclic Tension ◽  
Tension Tests ◽  
Almost All

Uniaxial ratchetting characteristics of 316FR steel at room temperature are studied experimentally. Cyclic tension tests, in which maximum strain increases every cycle by prescribed amounts, are conducted systematically in addition to conventional monotonic, cyclic, and ratchetting tests. Thus hysteresis loop closure, cyclic hardening and viscoplasticity are discussed in the context of constitutive modeling for ratchetting. The cyclic tension tests reveal that very slight opening of hysteresis loops occurs, and that neither accumulated plastic strain nor maximum plastic strain induces significant isotropic hardening if strain range is relatively small. These findings are used to discuss the ratchetting tests. It is thus shown that uniaxial ratchetting of the material at room temperature is brought about by slight opening of hysteresis loops as well as by viscoplasticity, and that kinematic hardening governs almost all strain hardening in uniaxial ratchetting if stress range is not large. [S0094-4289(00)00401-1]

Calculation of drawbead restraining forces with the Bauschinger effect

1998 ◽  
Vol 212 (7) ◽  
pp. 549-553 ◽  
Author(s):  
Y You
Keyword(s):  
Bauschinger Effect ◽  
Kinematic Hardening ◽  
Material Model ◽  
Constitutive Law ◽  
Isotropic Hardening ◽  
Hardening Material ◽  
Cyclic Property ◽  
Restraining Force ◽  
Comparison With Experiments ◽  
Better Than

In this paper, a numerical model for the calculation of the drawbead restraining force is described. The model is formulated using an elastoplastic finite deformation, finite element method. Because of the bending, unbending and reverse bending deformation which occurs as the sheet metal passes through the drawbead, a kinematic hardening constitutive law associated with a description of the cyclic property and the Bauschinger effect is considered. In comparison with experiments, the results based on the kinematic hardening material model proved to be better than those based on the usual isotropic hardening material model.

scholarly journals Experimental Investigation and FE Analysis on Constitutive Relationship of High Strength Aluminum Alloy under Cyclic Loading

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Yuanqing Wang ◽  
Zhongxing Wang
Keyword(s):  
Aluminum Alloy ◽  
Cyclic Loading ◽  
Kinematic Hardening ◽  
Compressive Strain ◽  
High Strength ◽  
Constitutive Relationship ◽  
Isotropic Hardening ◽  
Fe Model ◽  
High Strength Aluminum Alloy ◽  
Finite Element Software

Experiments of 17 high strength aluminum alloy (7A04) specimens were conducted to investigate the constitutive relationship under cyclic loading. The monotonic behavior and hysteretic behavior were focused on and the fracture surface was observed by scanning electron microscope (SEM) to investigate the microfailure modes. Based on Ramberg-Osgood model, stress-strain skeleton curves under cyclic loading were fitted. Parameters of combined hardening model including isotropic hardening and kinematic hardening were calibrated from test data according to Chaboche model. The cyclic tests were simulated in finite element software ABAQUS. The test results show that 7A04 aluminum alloy has obvious nonlinearity and ultra-high strength which is over 600 MPa, however, with relatively poor ductility. In the cyclic loading tests, 7A04 aluminum alloy showed cyclic hardening behavior and when the compressive strain was larger than 1%, the stiffness degradation and strength degradation occurred. The simulated curves derived by FE model fitted well with experimental curves which indicates that the parameters of this combined model can be used in accurate calculation of 7A04 high strength aluminum structures under cyclic loading.

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