Formability Analysis of Fukui Stretch-Drawing and Square Cup Drawing Using Strain and Stress Based Forming Limit Curves

2017 ◽  
Vol 751 ◽  
pp. 167-172 ◽  
Author(s):  
Sansot Panich ◽  
Nopparat Seemuang ◽  
Taratip Chaimongkon
Keyword(s):  
Flow Behavior ◽  
High Strength ◽  
Forming Limit ◽  
Forming Limit Curve ◽  
Yield Criteria ◽  
Hardening Law ◽  
Stress Curve ◽  
Strain Paths ◽  
Cup Drawing ◽  
Better Than

In this work, the experimental and numerical analyses of Forming Limit Curve (FLC) and Forming Limit Stress Curve (FLSC) for Advanced High Strength Steel (AHSS) sheet, grade JAC780Y, are performed. Initially, the FLC is experimentally determined by means of the Nakazima Stretch forming test. Subsequently, the FLSC of investigated steel was plastically calculated using the experimental FLC data. Different yield criteria including Hill48, and Yld89, are applied to describe plastic flow behavior of the AHS steel and Swift hardening law is taken into account. Hereby, influences of the constitutive yield models on the numerically determined FLSCs are evaluated regarding to those results from the experimental data. The obtained stress based forming limits are affected significantly by the yield criteria. Finally, the experimental and numerical formability analyses of Fukui stretch-drawing and square cup drawing tests are studied through FLC and FLSCs. It is observed that all stress based curves can be used very well to describe material formability of the examined steel compared to the strain based FLC. The strain based FLC depend on forming history and strain paths change. In the other hand, the stress based FLC do not depend on these issue. In this study, it can be concluded that the FLSCs could predict failure more realistically and better than the strain based FLC.

Development of Stress- and Strain-Based Fracture Forming Limit Curves of Sheet Aluminium-Alloy AA2024-T3 through Various Approaches

2020 ◽  
Vol 856 ◽  
pp. 57-65
Author(s):  
Tanakorn Jantarasricha ◽  
Sansot Panich ◽  
Komkamol Chongbunwatana
Keyword(s):  
Aluminium Alloy ◽  
Yield Criterion ◽  
Forming Limit ◽  
Forming Limit Curve ◽  
Fracture Locus ◽  
Hardening Law ◽  
Stress Curve ◽  
Anisotropic Yield Criterion ◽  
Strain Space ◽  
The Hill

In this work, four fracture criteria—namely, Fracture Forming Limit Curve (FFLC), Fracture Forming Limit Stress Curve (FFLSC), Fracture Locus (FL) and Fracture Locus Embedded with Bao-Wierzbicki Ductile Damage Criterion (BW-FL)—are comparatively deployed to forecast breakage of deformed AA2024-T3 sheet aluminium-alloy. An FFLC can be experimentally formed by conducting a set of Nakajima stretch-forming based tests. To obtain an FFLSC, such an FFLC drawn in the strain space has to be entirely mapped onto the stress space. This can computationally be accomplished with the help of those well-known plasticity-relevant models like the Hill’48 anisotropic yield criterion and the Swift hardening law. Likewise, both BW-FL and FL in terms of stress triaxialities and critical plastic strains can mathematically be derived from the FFLC incorporated with the Hill’48 anisotropic yield criterion. Hole expansion and tree-point bending tests are carefully carried out both experimentally and simulatively to verify those four generated fracture limits. The more innovative FFLSC and FL demonstrate more accurate prediction on rupture of AA2024-T3 sheet aluminium-alloy than the conventional FFLC. The BW-FL however performs the worst.

Forming Limit Curves and Forming Limit Stress Curves for Advanced High Strength Steels

2013 ◽  
Vol 773-774 ◽  
pp. 109-114 ◽  
Author(s):  
Sansot Panich ◽  
Frédéric Barlat ◽  
Vitoon Uthaisangsuk ◽  
Surasak Suranuntchai ◽  
Suwat Jirathearanat
Keyword(s):  
Yield Criterion ◽  
Flow Behavior ◽  
Constitutive Models ◽  
High Strength Steels ◽  
High Strength ◽  
Forming Limit ◽  
Advanced High Strength Steels ◽  
Hardening Law ◽  
Limit Stress ◽  
Forming Limit Curves

Experimental and numerical investigations using Forming Limit Curve (FLC) and Forming Limit Stress Curve (FLSC) were carried out for two Advanced High Strength Steel (AHSS) grades DP780 and TRIP780. The forming limit curves were experimentally determined by means of Nakazima stretching test. Then, both FLC and FLSC were analytically calculated on the basis of the Marciniack-Kuczinsky (M-K) model. The yield criteria Barlat2000 (Yld2000-2d) were employed in combination with the Swift and modified Voce strain hardening laws to describe plastic flow behavior of the AHS steels. Hereby, influence of the constitutive models on the numerically determined FLCs and FLSCs were examined. Obviously, the forming limit curves predicted by the M-K model applying the Yld2000-2d yield criterion and Swift hardening law could fairly represent the experimental limit curves. The FLSCs resulted from the experimental data and theoretical model were also compared.

Effects of Anisotropic Yield Functions on Prediction of Forming Limit Diagram for AHS Steel

2014 ◽  
Vol 622-623 ◽  
pp. 257-264
Author(s):  
Sansot Panich ◽  
Vitoon Uthaisangsuk
Keyword(s):  
Biaxial Tension ◽  
Yield Criterion ◽  
Forming Limit Diagram ◽  
High Strength ◽  
Forming Limit ◽  
Bulge Test ◽  
Yield Criteria ◽  
Hardening Law ◽  
Yield Functions ◽  
Work Hardening Coefficient

In this study, experimental and numerical analyses of Forming Limit Diagram (FLD) for Advanced High Strength (AHS) steel grade 980 were performed. Forming limit curve was first determined by means of the Nakazima stretch-forming test. Then, analytical calculations of the FLD based on the Marciniak-Kuczynski (M-K) model were carried out. Different yield criteria, namely, Hill’48 (r-value and stress-based), Yld89 (r-value and stress-based) and Barlat2000 (Yld2000-2d) were investigated. The strain hardening law according to Swift was applied. To identify parameters of each model, uniaxial tension, balanced bi-axial bulge test and in-plane biaxial tension test were performed. As a result, predicted plastic flow stresses and plastic anisotropies of the AHS steel by various directions were evaluated. In addition, effects of the anisotropic yield functions, strain rate sensitivities, imperfection values and work hardening coefficient on the predicted FLD were studied and discussed. It was found that the FLD based on the Yld2000-2d yield criterion was in better agreement with the experimental curve. Accuracy of the FLD predictions based on the M-K theory, especially in the biaxial state of stress, significantly depended on the applied yield criteria, for which yield stresses and r-values of different loading directions were required.

Identification of Process-Based Limit Stress States Applying a Stretch-Bending-Test

2012 ◽  
Vol 504-506 ◽  
pp. 47-52
Author(s):  
Christian Hezler ◽  
Marion Merklein ◽  
Joachim Hecht ◽  
Bernd Griesbach
Keyword(s):  
High Strength ◽  
Bending Test ◽  
Forming Limit ◽  
Limit Curve ◽  
Forming Process ◽  
Forming Limit Curve ◽  
Distribution Diagram ◽  
Stress Limit ◽  
Stretch Bending ◽  
Strain Paths

The evaluation of forming simulation by using the forming limit curve has only limited validity if it is applied on car body components with non-linear strain paths. If modern high strength materials are used, the forming limit criteria can also provide invalid predictions. Especially high strength multiphase steels show a specific behaviour in forming, necking and crack initiation. If bending loads are applied to these materials, the onset of cracking occurs partially not within the range of the forming limit curve (FLC). The stress limit indicates the failure beginning more accurate. It is independent of the forming history and should be less sensitive to the behaviour of high strength steels. In the post processing of a simulation it could be used similar to the forming limit. A limit curve applied on the in-plane-stress-diagram of an analysed component defines areas that are more vulnerable for cracking. The required stress limit curve will be obtained in this research by applying a stretch-bending-test. It is selected in order to reach loads, which are comparable to the forming process in the components’ production. The forming state that is affecting the specimen is a combination of bending and stretching load. Different load conditions can be applied at the test by altering the stamp-radius and the specimen geometry. Since stresses cannot be measured directly in the experiment, the test is modelled in the simulation where the stresses can be calculated for a given material model. Finally the stress limit criterion was applied on the test parts’ stress distribution diagram. Occurring stresses above the stress limit curve are displayed on the simulation. Thereby it is possible to show a good correlation in critical areas between the failure prediction in the simulation and occurring rupture on the test component.

The Microstructure and Formability Study on DP Steel of Lightweight Automobile

2011 ◽  
Vol 704-705 ◽  
pp. 1465-1472
Author(s):  
Jin Wu ◽  
Da Sen Bi ◽  
Liang Chu ◽  
Jian Zhang ◽  
Yun Tao Li
Keyword(s):  
Mechanical Property ◽  
Work Hardening ◽  
High Strength Steel ◽  
High Strength ◽  
Mathematic Model ◽  
Theoretical Research ◽  
Forming Limit ◽  
Strain Hardening Exponent ◽  
Dp Steel ◽  
Better Than

Dual phase (DP) steel is a high strength steel for auto-panel. In this paper, mechanical property, forming ability, baked-hardening and work hardening properties of high strength steel DP450 are studied by experiments, and compared with those of steel MS6000.And theoretical research on predicting the forming limit of steel DP450 by the NADDRG model. The established mathematic model for relativity is of practical usefulness. Experimental results reveal that the yield strength of steel DP450 is about 7.2% lower than the MS6000,and the break strength increases by 18.9%,while the elongation increases by 19%.The strain hardening exponent of steel DP450 are superior to those of MS6000.The results show that mechanical property of high strength steel DP450 is better than that of MS6000,while forming ability of DP450 is not lower than that of MS6000.And baked-hardening and work hardening properties of steel DP450 are better than those of MS6000.The steel sheet DP450 owned a good forming ability.

Experimental Investigation on Forming Limit Curve at Elevated Temperature Through Dome and Biaxial Test

2020 ◽  
Author(s):  
Chetan P. Nikhare ◽  
Evan Teculver ◽  
Faisal Aqlan
Keyword(s):  
Air Pollution ◽  
Fuel Consumption ◽  
Axial Stress ◽  
High Strength ◽  
Tension Test ◽  
Forming Limit ◽  
Biaxial Test ◽  
Limit Curve ◽  
Forming Limit Curve ◽  
Stress States

Abstract The characteristics of metal and materials are very important to design any component so that it should not fail in the life of the service. The properties of the materials are also an important consideration while setting the manufacturing parameters which deforms the raw material to give the design shape without providing any defect or fracture. For centuries the commonly used method to characterize the material is the traditional uniaxial tension test. The standard has been created for this test by American Standard for Testing Materials (ASTM) – E8. This specimen is traditionally been used to test the materials and extract the properties needed for designing and manufacturing. It should be noted that the uniaxial tension test uses one axis to test the material i.e., the material is pulled in one direction to extract the properties. The data acquired from this test found enough for manufacturing operations of simple forming where one axis stretching is dominant. Recently a sudden increase in the usage of automotive vehicles results in sudden increases in fuel consumption which results in an increase in air pollution. To cope up with this challenge federal government is implying the stricter environmental regulation to decrease air pollution. To save from the environmental regulation penalty vehicle industry is researching innovation which would reduce vehicle weight and decrease fuel consumption. Thus, the innovation related to light-weighting is not only an option anymore but became a mandatory necessity to decrease fuel consumption. To achieve this target, the industry has been looking at fabricating components from high strength to ultra-high strength steels or lightweight materials. This need is driven by the requirement of 54 miles per gallon by 2025. In addition, the complexity in design increased where multiple individual parts are eliminated. This integrated complex part needs the complex manufacturing forming operation as well as the process like warm or hot forming for maximum formability. The complex forming process will induce the multi-axial stress states in the part, which is found difficult to predict using conventional tools like tension test material characterization. In many pieces of literature limiting dome height and bulge tests were suggested analyzing these multi-axial stress states. However, these tests limit the possibilities of applying multi-axial loading and resulting stress patterns due to contact surfaces. Thus, a test machine called biaxial test is devised which would provide the capability to test the specimen in multi-axial stress states with varying load. In this paper, two processes, limiting dome test and biaxial test were experimented to plot the forming limit curve. The forming limit curve serves the tool for the design of die for manufacturing operation. For experiments, the cruciform test specimens were used in both limiting dome test and biaxial test and tested at elevated temperatures. The forming limit curve from both tests was plotted and compared. In addition, the strain path, forming, and formability was investigated and the difference between the tests was provided.

scholarly journals Effects of strain paths on the fracture forming limit of high strength structural steel sheets

2020 ◽  
Vol 1605 ◽  
pp. 012078
Author(s):  
Teng Xu ◽  
Qin-xiang Xia ◽  
Zhen-jie Qi ◽  
Xiao-yu Wu ◽  
Jia-qi Ran ◽  
...  
Keyword(s):  
Structural Steel ◽  
High Strength ◽  
Forming Limit ◽  
Steel Sheets ◽  
Strain Paths

Effect of Strain Paths on Formability Evaluation of TRIP Steels

2010 ◽  
Vol 89-91 ◽  
pp. 214-219 ◽  
Author(s):  
David Gutiérrez ◽  
A. Lara ◽  
Daniel Casellas ◽  
Jose Manuel Prado
Keyword(s):  
Strain Path ◽  
High Strength Steels ◽  
High Strength ◽  
Test Method ◽  
Forming Limit ◽  
Trip Steels ◽  
Advanced High Strength Steels ◽  
Strain Paths ◽  
Analysis System

The Forming Limit Diagrams (FLD) are widely used in the formability analysis of sheet metal to determine the maximum strain, which gives the Forming Limit Curve (FLC). It is well known that these curves depend on the strain path during forming and hence on the test method used to calculate them. In this paper, different stretching tests such as the Nakajima and the Marciniak tests were performed, with different sample geometries to obtain points in different areas of the FLD. An optical analysis system was used, which allows following the strain path during the test. The increasing use of advanced high-strength steels (AHSS) has created an interest in determining the mechanical properties of these materials. In this work, FLCs for a TRIP steel were determined using Nakajima and Marciniak tests, which revealed different strain paths depending on the type of test. Determination of the FLCs was carried out following the mathematical calculations indicated in the ISO 12004 standard and was also compared with an alternative mathematical method, which showed different FLCs. Finally, the tests were verified by comparing the strain paths of the Nakajima and Marciniak tests with a well-known mild steel.

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