Effect of Ductile Damage Evolution in Sheet Metal Forming: Experimental and Numerical Investigations

2010 ◽  
Vol 446 ◽  
pp. 157-169 ◽  
Author(s):  
Fethi Abbassi ◽  
Olivier Pantalé ◽  
Sébastien Mistou ◽  
Ali Zghal ◽  
Roger Rakotomalala
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Rolling Direction ◽  
Constitutive Law ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Plastic Behavior ◽  
Marquardt Algorithm

The numerical simulation based on the Finite Element Method (FEM) is widely used in academic institutes and in the industry. It is a useful tool to predict many phenomena present in the classical manufacturing forming processes such as necking, fracture, springback, buckling and wrinkling. But, the results of such numerical model depend strongly on the parameters of the constitutive behavior model. In the first part of this work, we focus on the traditional identification of the constitutive law using oriented tensile tests (0°, 45°, and 90° with respect to the rolling direction). A Digital Image Correlation (DIC) method is used in order to measure the displacements on the surface of the specimen and to analyze the necking evolution and the instability along the shear band. Therefore, bulge tests involving a number of die shapes (circular and elliptic) were developed. In a second step, a mixed numerical–experimental method is used for the identification of the plastic behavior of the stainless steel metal sheet. The initial parameters of the inverse identification were extracted from a uniaxial tensile test. The optimization procedure uses a combination of a Monte-Carlo and a Levenberg-Marquardt algorithm. In the second part of this work, according to some results obtained by SEM (Scaning Electron Microscopy) of the crack zones on the tensile specimens, a Gurson Tvergaard Needleman (GTN) ductile model of damage has been selected for the numerical simulations. This model was introduced in order to give informations concerning crack initiations during hydroforming. At the end of the paper, experimental and numerical comparisons of sheet metal forming applications are presented and validate the proposed approach.

Effect of specimen orientation to the rolling direction on uniaxial tensile forming and failure limits

2020 ◽  
Vol 234 (13) ◽  
pp. 1598-1603
Author(s):  
Puja Ghosal ◽  
Surajit Kumar Paul
Keyword(s):  
Sheet Metal ◽  
Ferritic Steel ◽  
Dual Phase Steel ◽  
Rolling Direction ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Correlation Technique ◽  
Dual Phase ◽  
Planar Anisotropy

Alteration of forming and failure limits due to planar anisotropy of the sheet metal significantly affects the safe forming operation region and finally successfully manufacturing of a sheet metal formed component. This article presents the effect of planar anisotropy on uniaxial tensile properties, forming and failure limits of cold-rolled ferritic and dual-phase steels. In-situ three dimensional digital image correlation technique is used to measure the evolution of local strain components during uniaxial tensile test. For both the steels, necking limit is highest for the specimen at an orientation of 90° to rolling direction, while failure limit is highest for those specimen whose orientation is 45° to rolling direction for ferritic steel, and both 0° and 90° to rolling direction for dual-phase steel. Uniaxial tensile deformation path for ferritic steel holds lower slope than dual-phase steel as depicted in major versus minor strain plot.

scholarly journals Coupled Thermomechanical Response Measurement of Deformation of Nickel-Based Superalloys Using Full-Field Digital Image Correlation and Infrared Thermography

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2163
Author(s):  
Krzysztof Żaba ◽  
Tomasz Trzepieciński ◽  
Sandra Puchlerska ◽  
Piotr Noga ◽  
Maciej Balcerzak
Keyword(s):  
Surface Temperature ◽  
Strain Rate ◽  
Rolling Direction ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Response Measurement ◽  
Sheet Rolling ◽  
Inconel Alloys ◽  
The Relationship

The paper is devoted to highlighting the potential application of the quantitative imaging technique through results associated with work hardening, strain rate and heat generated during elastic and plastic deformation. The aim of the research presented in this article is to determine the relationship between deformation in the uniaxial tensile test of samples made of 1-mm-thick nickel-based superalloys and their change in temperature during deformation. The relationship between yield stress and the Taylor–Quinney coefficient and their change with the strain rate were determined. The research material was 1-mm-thick sheets of three grades of Inconel alloys: 625 HX and 718. The Aramis (GOM GmbH, a company of the ZEISS Group) measurement system and high-sensitivity infrared thermal imaging camera were used for the tests. The uniaxial tensile tests were carried out at three different strain rates. A clear tendency to increase the sample temperature with an increase in the strain rate was observed. This conclusion applies to all materials and directions of sample cutting investigated with respect to the sheet-rolling direction. An almost linear correlation was found between the percent strain and the value of the maximum surface temperature of the specimens. The method used is helpful in assessing the extent of homogeneity of the strain and the material effort during its deformation based on the measurement of the surface temperature.

scholarly journals Modelling of Friction Phenomena Existed in Drawbead in Sheet Metal Forming

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5887
Author(s):  
Tomasz Trzepieciński ◽  
Andrzej Kubit ◽  
Romuald Fejkiel ◽  
Łukasz Chodoła ◽  
Daniel Ficek ◽  
...  
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Rolling Direction ◽  
Back Propagation ◽  
Experimental Tests ◽  
Friction Model ◽  
Friction Reduction ◽  
Training Algorithms ◽  
Sheet Rolling

The article presents the results of friction tests of a 0.8 mm-thick DC04 deep-drawing quality steel sheet. A special friction simulator was used in the tests, reflecting friction conditions occurring while pulling a sheet strip through a drawbead in sheet metal forming. The variable parameters in the experimental tests were as follows: surface roughness of countersamples, lubrication conditions, sample orientation in relation to the sheet rolling direction as well as the sample width and height of the drawbead. Due to many factors that affect the value of the coefficient of friction coefficient, artificial neural networks (ANNs) were used to build and analyse the friction model. Four training algorithms were used to train the ANNs: back propagation, conjugate gradients, quasi-Newton and Levenberg–Marquardt. It was found that for all analysed friction conditions and sheet strip widths, increasing the drawbead height increases the COF value. The chlorine-based Heavy Draw 1150 compound provides a more effective friction reduction compared to a LAN-46 machine oil.

scholarly journals Blank shape optimization considering 3D space targets for external and internal boundaries in sheet metal forming processes

2021 ◽  
Author(s):  
Hamidreza Gharehchahi ◽  
Mohammad Javad Kazemzadeh-Parsi ◽  
Ahmad Afsari ◽  
Mehrdad Mohammadi
Keyword(s):  
Sheet Metal ◽  
Optimum Design ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Production Costs ◽  
Internal Boundary ◽  
Optimum Shape ◽  
Plastic Behavior ◽  
3D Space ◽  
Blank Shape

Abstract The optimum design of an initial blank shape in sheet metal forming processes is an important step in many industries, especially automobile manufacturers because it reduces production costs and material waste. To the best of our knowledge, no research has been conducted on the blank shape designs based on 3D space target contours. Moreover, the present study considers parts with internal boundaries and optimum design of the internal boundary, which are among the innovations of this research. By following the iterative simulation-based optimization process, a special updating algorithm was proposed to modify the blank geometry in each iteration and reach the optimum shape. The sheet forming was severely nonlinear, due to plastic behavior, large deformations, and frictional contact surfaces. Therefore, the updating formula should be robust enough to be insensitive to the initial guess for the blank. To evaluate the proposed updating formula, some numerical examples were solved and the results were presented. Finally, the robustness of the proposed algorithm was investigated in these numerical experiences, by considering different geometries, target contours, internal boundaries, and initial guesses. The present study reveals that the proposed algorithm can be effectively used to solve blank optimization problems for the deep drawing process.

MECHANICAL CHARACTERIZATION OF NOTCHED HOT ROLLED MULTI-PHASE STEEL

2017 ◽  
Vol 41 (1) ◽  
pp. 39-50
Author(s):  
Ke Niu ◽  
Abdolhamid Akbarzadeh ◽  
Zengtao Chen
Keyword(s):  
Crack Formation ◽  
Sheet Steel ◽  
Rolling Direction ◽  
Experimental Studies ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Correlation Technique ◽  
Stretch Flanging ◽  
Hot Rolled

This paper presents a series of experimental and numerical studies on Hot Rolled Stretch Flanging steels. This study focuses on four prototyped Hot-Rolled Stretch Flanging steels (HR780SF). Circular- notched sheet steel samples are used to induce different stress triaxiality levels in the rolling direction of sheet materials. Digital image correlation technique measures the local true strain during the deformation process of the notched samples in uniaxial tensile test. The microstructure of the notched samples is examined to evaluate the effect of geometrical features of circular notches on the microstructural evolution during the plastic deformation. Finally, the numerical results obtained via a finite element simulation are validated by the collected experimental data. Our experimental studies reveal the possibility of crack formation along the width of HR780SF steels during the mechanical load. The crack formation, which deteriorates the structural performance of hot rolled steels, can be avoided by the heat treatment of samples prior to the mechanical tests. In addition, it is found that the effect of notch geometry on the stress state is much more considerable at the notch edge than the notch center.

A New Method for Testing Formability in Sheet Metal Forming at Biaxial Tensile State

2014 ◽  
Vol 626 ◽  
pp. 275-280 ◽  
Author(s):  
Rong Shean Lee ◽  
Ta Wei Chien
Keyword(s):  
Experimental Data ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Experimental Results ◽  
New Method ◽  
Dome Height ◽  
Uniaxial Tensile ◽  
Biaxial Tensile ◽  
Theoretical Predictions

This paper presents a new method concerning testing formability in sheet metal forming, especially focuses on clarifying the divergence of the experiment and a variety of theoretical predictions on biaxial tensile state. Up to now, there are many different fracture criteria appeared. All researches have presented their experimental data which could justify the criterion they presented. However, the experimental results and predictions in the first quadrant of the forming limit diagram (FLD) often diverge. Today, limiting dome height test is commonly used for FLD experiment, but specimens are rubbed and bended during the test, both influencing the experimental results.In order to provide for convincible experimental data, this paper presents a new experimental method to establish the first quadrant of FLD. In this method, cruciform biaxial tensile specimen and biaxial tensile apparatus have been developed. The proposed specimen has the feature of thickness reduction and contour design to ensure the fracture location is in the central region, so that accurate biaxial tensile state can be obtained. Through this method, there is an opportunity to obtain the whole FLD using uniaxial tensile testing machine, which is a low-cost alternative in compared with limiting dome height test. Besides, the experimental results can be utilized to clarify the divergence between various theoretical predictions and experimental results in the first quadrant of the FLD.

Effects of Rolling Direction and Lubricant on Friction in Sheet Metal Forming

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Xiaojun Liu ◽  
Mathias Liewald ◽  
Dina Becker
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Rolling Direction ◽  
Alloy Sheet ◽  
Friction Behavior ◽  
Drawing Test ◽  
Strip Drawing ◽  
The Coefficient Of Friction ◽  
Surface Microstructures

Lubrication and friction at workpiece-tool interface play an important role in product quality control of sheet metal forming process. Surface microstructures of sheets have a great influence on the development of lubrication films. In order to investigate the effects of the rolling direction of aluminum alloy sheet and lubricant on the friction behavior in sheet metal forming, strip drawing test was used. The sample used was electric discharge texturing (EDT) surface. Lubricants, both with and without additives, were used. The strip drawing tests were performed at angles between the sliding and rolling directions of 0–90 deg. Variations in the sheet surface topography were analyzed by comparing the sheet surface microstructures and its 3D surface parameters before and after the strip drawing test. Results of the strip drawing tests indicate that the kind and amount of lubricant have great influences on friction at the interface, and the lubricant with additives benefits improving the friction behavior between the sheet and the tool. The EDT surface of the aluminum alloy sheet has an anisotropic frictional property during deep drawing process due to different angles between the sliding and rolling directions. When the sliding direction is parallel to the rolling direction, the coefficient of friction has the highest value. When the angle between the sliding and rolling directions increases, the coefficient of friction decreases. The surface microstructure of the sheets after the strip drawing test at different angles between the sliding and rolling directions has been modified, and its 3D surface parameters decrease significantly to a different degree.

Application of Associated and Non-Associated Flow Metal Plasticity for F.S.S Sheet

2021 ◽  
Vol 406 ◽  
pp. 473-480
Author(s):  
Oualid Chahaoui ◽  
Houssem Soltani ◽  
Nadjoua Matougui
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Mechanical Anisotropy ◽  
Flow Rule ◽  
Plastic Behavior ◽  
Sheet Plane ◽  
Yield Criteria ◽  
Plastic Potential ◽  
Associated Flow Rule

In the last decade, several phenomenological yield criteria for anisotropic material has been proposed to improve the modeling predictions about sheet metal-forming processes. In regard to this engineering application, two proprieties of models have been used. If the yield function and the plastic potential are not same (not equal), the normality rule is non associative flow rule (NAFR), otherwise, when the stresses yield has been completely coupled to the anisotropic strain rate ratio (plastic potential), is called the associated flow rule (AFR). The non-associated flow rule is largely adopted to predict a plastic behavior for metal forming, accurately about à strong mechanical anisotropy presents in sheet metal forming processes. However, various studies described the limits of the AFR concept in dealing with highly anisotropic materials. In this study, the quadratic Hill1948 yield criteria is considered to predict mechanical behavior under AFR and NAFR approach. Experiment and modeling predictions behaviour of normalized anisotropic coefficient r (θ) and σ (θ) evolved with θ in sheet plane. and the equibiaxial yield stress σb was assumed σb=1 but the rb-values was computed from Yld96 [15].

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