Effect of Thickness on the Pure Stretchability of Aluminum Sheets

1990 ◽  
Vol 112 (4) ◽  
pp. 340-345 ◽  
Author(s):  
M. Kobayashi ◽  
Y. Kurosaki ◽  
N. Kawai
Keyword(s):  
Frictional Coefficient ◽  
Thickness Dependence ◽  
Aluminum Sheet ◽  
Sheet Metals ◽  
Aluminum Sheets ◽  
K Theory ◽  
Good Agreement ◽  
Diffuse Neck

The effects of the thickness, lubricant, and temper of metals on pure stretchability of aluminum sheets have been studied. The pure stretchability of the sheet metals was markedly deteriorated by decreasing both the thickness in every lubricant and the temper of metal used in this experiment. The optimum frictional coefficient, which gives a maximum of the critical forming depth, was found in this experiment, and it was confirmed to change with the thickness and temper of metal. The thickness dependence of the critical forming depth was analytically calculated by means of Hill’s diffuse neck criterion, Yamaguchi’s method based on M-K theory and the criterion proposed by Gotoh. The result calculated by Yamaguchi’s method was comparatively in good agreement with the experiment in soft aluminum sheet and the result by Gotoh’s method did so in the half-hard one.

scholarly journals Study of Influence of Width to Thickness Ratio in Sheet Metals on Bendability under Ambient and Superimposed Hydrostatic Pressure

2021 ◽  
Vol 2 (3) ◽  
pp. 542-558
Author(s):  
Mohammadmehdi Shahzamanian ◽  
David Lloyd ◽  
Amir Partovi ◽  
Peidong Wu
Keyword(s):  
Hydrostatic Pressure ◽  
Stress Ratio ◽  
Fracture Strain ◽  
Stress Triaxiality ◽  
Volumetric Strain ◽  
Thickness Ratio ◽  
Sheet Metals ◽  
The Finite Element Method ◽  
Bending Strain ◽  
Good Agreement

The effect of the width to thickness ratio on the bendability of sheet metal is investigated using the finite element method (FEM) employing the Gurson–Tvergaard–Needleman (GTN) model. Strain path changes in the sheet with change in the width/thickness ratio. It is shown that bendability and fracture strain increase significantly by decrease in the width/thickness ratio. The stress state is almost uniaxial when the stress ratio (α) is close to zero for narrow sheets. Stress ratio is nothing but the major stress to minor stress ratio. This delays the growth and coalescence of micro-voids as the volumetric strain and stress triaxiality (pressure/effective stress) decrease. On the other hand, ductility decreases with increase in α for wider sheets. Fracture bending strain is calculated and, as expected, it increases with decrease in the width/thickness ratio. Furthermore, a brief study is performed to understand the effect of superimposed hydrostatic pressure on fracture strain for various sheet metals with different width/thickness ratios. It is found that the superimposed hydrostatic pressure increases the ductility, and that the effect of the width/thickness ratio in metals on ductility is as significant as the effect of superimposed hydrostatic pressure. Numerical results are found to be in good agreement with experimental observations.

scholarly journals Research on reliability of punch bonding technology with steel-aluminum sheet metals

2016 ◽  
Vol 52 (01) ◽  
pp. 65-70
Author(s):  
F. LI ◽  
G. N. CHU ◽  
M. D. XU ◽  
X. C. SUI ◽  
W. SHI
Keyword(s):  
Aluminum Sheet ◽  
Sheet Metals ◽  
Bonding Technology

Modeling of Necking/Shear Failure of Aluminum Sheet Metals With Consideration of Void Nucleation and Growth

2001 ◽  
Author(s):  
W. Y. Chien ◽  
J. Pan ◽  
S. C. Tang
Keyword(s):  
Plane Strain ◽  
Shear Failure ◽  
Failure Strain ◽  
Void Nucleation ◽  
Sheet Material ◽  
Plastic Anisotropy ◽  
Rate Sensitivity ◽  
Sheet Metals ◽  
Plane Strain Tension ◽  
Aluminum Sheets

Abstract Failure of two aluminum sheets, AA5754 and AA6111, under stretching conditions is analyzed using a combined plane stress and plane strain approach. The sheet material is modeled by an elastic-viscoplastic constitutive relation that accounts for material plastic anisotropy, material rate sensitivity, and the softening due to the nucleation, growth, and coalescence of microvoids. Failure processes of sheet metals are modeled under plane strain tension. Also, failure strains are determined under bending conditions when the necking mode is suppressed. The results are consistent with experimental observations where the failure strain of the aluminum sheets increases significantly under bending conditions. The results indicate that when a considerable amount of necking is observed under stretching conditions, failure strains under bending conditions are higher.

Plastic-Bending of Adhesively Bonded Dissimilar Sheet Metals

2013 ◽  
Vol 535-536 ◽  
pp. 418-421 ◽  
Author(s):  
Michihiro Takiguchi ◽  
Taro Tokuda ◽  
Tetsuya Yoshida ◽  
Mitsuo Funaki ◽  
Hiroshi Hamasaki ◽  
...  
Keyword(s):  
High Speed ◽  
Adhesive Layer ◽  
Sheet Metals ◽  
High Tensile Strength ◽  
Adhesively Bonded ◽  
Plastic Bending ◽  
High Speed Forming ◽  
Plastic Forming ◽  
Lower Temperature ◽  
Good Agreement

In this paper, the effect of material characteristics on plastic forming of adhesively bonded dissimilar sheet metals was investigated by experiments and finite element method (FEM). The acrylic adhesive employed in the experiments has visco-plasticity characteristics with high ductility and strong strain-rate and temperature sensitivity in strength. Major results obtained are summarized as follows: (1) In the adhesively bonded dissimilar sheet metals, the gull-wing bend and the shear deformation of the adhesive layer are suppressed by the combination of the sheet metals when a bending inside sheet has high-tensile strength. (2) The gull-wing bend is suppressed by high-speed forming at a lower temperature as well as the same kind of sheet metals. (3) The calculated results using MSC Marc2010 are relatively good agreement with the experimental results.

Constitutive Equations of Stress-Strain Responses of Aluminum Sheet under Stress Path Changes

2013 ◽  
Vol 535-536 ◽  
pp. 101-104
Author(s):  
Takeshi Uemori ◽  
Satoshi Sumikawa ◽  
Shohei Tamura ◽  
Fusahito Yoshida
Keyword(s):  
Experimental Data ◽  
Constitutive Model ◽  
Present Author ◽  
Plastic Anisotropy ◽  
Stress Path ◽  
Aluminum Sheet ◽  
Light Weight ◽  
Sheet Metals ◽  
Proportional Loading ◽  
Strain Responses

Aluminum sheet metals have been widely utilized for a light weight construction of automobile. However, these metals still remain one of the difficult materials to predict the accurate final shapes after press forming processes, because of several mechanical weak features such as strong plastic anisotropy of yield stress, large Lankford value, and so on. In order to solve the problems, the present author has developed a new constitutive model. The model can describe accurate non-proportional hardening behaviors of an aluminum sheet metal. In the present research, several experimental procedures were carried out to reveal the mechanical properties of an aluminum sheet under proportional and non-proportional loading. From the comparisons between experimental data and the corresponding calculated results by the proposed constitutive model, the performance of our model was evaluated. The evaluation of some springback analyses were also carried out. The calculated results show good agreements with the corresponding experimental data.

Prediction of Trimming Process Parameters in Aluminum Sheet Materials Using FE Method

2004 ◽  
Author(s):  
Quan Situ ◽  
Mukesh K. Jain ◽  
Don R. Metzger
Keyword(s):  
Process Parameters ◽  
Fracture Initiation ◽  
Material Model ◽  
Aluminum Sheet ◽  
The Finite Element Method ◽  
Fe Method ◽  
Cut Edge ◽  
Sheet Materials ◽  
Material Separation ◽  
Good Agreement

The trimming process is an important step to achieve good dimension and shape of a final product. However, it requires a systematic study of the various parameters involved in material separation. The finite element method was utilized to simulate the trimming process of aluminum sheet materials in aspects of material properties, tooling conditions and process parameters, including different tool configurations, clearances and punch speeds. Punch load versus displacement diagrams and cut edge morphologies obtained from representative clearances and tool configurations were investigated. A two-dimensional plane strain trimming was analyzed using a rate independent material model. An experimentally measured fracture strain was utilized in FE modeling for fracture initiation and development using element deletion technique. A thermally coupled material model was tentatively tested. Results from simulations were compared with experiments and good agreement was obtained for most of the studied conditions. Optimal trimming process parameters such as specific tool configuration, clearance and punch speed are suggested.

Crystallography of the Low Angle Lamellar Band Boundaries in ARB- Processed Aluminum Sheet

2011 ◽  
Vol 702-703 ◽  
pp. 161-164
Author(s):  
M. Zakaria Quadir ◽  
Michael Ferry ◽  
P. R. Munroe
Keyword(s):  
Accumulative Roll Bonding ◽  
Structural Features ◽  
Aluminum Sheet ◽  
Extensive Investigation ◽  
Sheet Metals ◽  
High Angle ◽  
Structural Refinement ◽  
Roll Bonding ◽  
Dense Distribution ◽  
Crystallographic Orientations

Lamellar bands are the primary structural features in accumulative roll bonding (ARB) of sheet metals. The structural refinement in ARB sheets occur by forming a dense distribution of lamellar band boundaries. The lamellar band boundaries initiate as low angle interfaces, parallel to the existing lamellar band boundaries, irrespective of the crystallographic orientations of the parent lamellar bands. From an extensive investigation it was found that the transverse directions across the lamellar band boundaries are rotated by an angle equal to their misorientations. Such a phenomenon is not sustained when the boundaries turn to high angle.

A Gurson Yield Function for Anisotropic Porous Sheet Metals and its Applications to Failure Prediction of Aluminum Sheets

2003 ◽  
Vol 19 (1) ◽  
pp. 161-168 ◽  
Author(s):  
D.-A. Wang ◽  
W. Y. Chien ◽  
K. C. Liao ◽  
J. Pan ◽  
S. C. Tang
Keyword(s):  
Finite Element ◽  
Cell Model ◽  
Three Dimensional ◽  
Yield Function ◽  
Sheet Metals ◽  
Element Analysis ◽  
Aluminum Sheets ◽  
Anisotropic Yield Function ◽  
The Matrix ◽  
Three Dimensional Finite Element

ABSTRACTAn approximate anisotropic yield function is presented for anisotropic sheet metals containing spherical voids. Hill's quadratic anisotropic yield function is used to describe the anisotropy of the matrix. The proposed yield function is validated using a three-dimensional finite element analysis of a unit cell model under different straining paths. The results of the finite element computations are shown in good agreement with those based on the yield function with three fitting parameters. For demonstration of applicability, the anisotropic Gurson yield function is adopted in a combined necking and shear localization analysis to model the failure of AA6111 aluminum sheets under biaxial stretching conditions.

Penetration Deep of Non-Deformable Projectile into Concrete Targets

2012 ◽  
Vol 446-449 ◽  
pp. 3604-3608
Author(s):  
Wei Wei Sun ◽  
Jun Yuan
Keyword(s):  
Penetration Depth ◽  
Unconfined Compressive Strength ◽  
Frictional Coefficient ◽  
Cavity Expansion ◽  
Stress Difference ◽  
Additional Mass ◽  
Depth Of Penetration ◽  
Penetration Data ◽  
The Relationship ◽  
Good Agreement

A dynamic cavity-expansion penetration model for concrete targets impacted by non-deformable projectile is developed. Based on the dynamic cavity-expansion penetration model, the equations of the final penetration depth were determined including the effect of additional mass and sliding frictional coefficient. The predicted final Penetration depth was compared with the depth of penetration data and a good agreement was achieved. The analysis indicated the additional mass was negligible compared to the mass of the projectile and independent of the striking velocity. When the friction between the concrete and the nose surface is assumed to be negligible, the final penetration depth increases slightly. The relationship between the principle stress difference at failure and unconfined compressive strength was determined by curve fitting.

The Welding Mechanism in Drawing of Aluminum Sheet

1980 ◽  
Vol 102 (3) ◽  
pp. 229-238 ◽  
Author(s):  
N. Kawai ◽  
T. Nakamura ◽  
S. Seko
Keyword(s):  
Shear Stress ◽  
Mild Steel ◽  
Steel Sheet ◽  
Testing Machine ◽  
Frictional Coefficient ◽  
Aluminum Sheet ◽  
Drawing Process ◽  
Mineral Oils ◽  
Friction Testing ◽  
Frictional Shear Stress

As a continuation of the previous report which dealt with a mild steel sheet, this study covers the welding phenomena at a tool-work interface in deformation processing of aluminum sheet which has been investigated experimentally by using a two dimensional drawing-type friction testing machine. Variation mode of the frictional coefficient during the drawing process can be classified into four types, namely,- constant, increasing, decreasing and waving type. In both the increasing and decreasing types, the welding occurs at a die exit portion, similar to the case of mild steel reported previously. In the waving type, a process of growth and the peeling away of the welding layer is repeated at a central portion of the die, and corresponding frictional coefficient waves develop. The frictional shear stress on the welding region is constant (about 68.6 MPa), approximately equaling the yield shear stress of the aluminum. The ability to repair the welding has been examined by measurement of the frictional coefficient at the designated drawing travel for mineral oils with various viscosities and compositions.

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