Prediction of spring-back in anisotropic sheet metals

2004 ◽  
Vol 218 (6) ◽  
pp. 651-661 ◽  
Author(s):  
V T Nguyen ◽  
Z Chen ◽  
P F Thomson
Keyword(s):  
Constitutive Equations ◽  
Bauschinger Effect ◽  
Yield Criterion ◽  
Yield Function ◽  
Alloy Sheet ◽  
Sheet Metals ◽  
Spring Back ◽  
Bending Tests ◽  
Numerical Predictions ◽  
Draw Bending

Constitutive equations for plane stress problems based on the modified form of a non-quadratic yield criterion suitable for aluminium alloy sheet were derived by Barlat et al. to account for the Bauschinger effect (BE). Numerical predictions of spring-back based on the original yield function and its modified form wer performed and compared with the results of draw-bending tests. The results show the necessity of including the BE in the constitutive equations to enhance the accuracy in predicting spring-back.

Special Issue on Engineering Plasticity: Prediction of spring-back in anisotropic sheet metals

2004 ◽  
Vol 218 (9) ◽  
pp. 1087-1087
Author(s):  
V T Nguyen ◽  
Z Chen ◽  
P F Thomson
Keyword(s):  
Constitutive Equations ◽  
Bauschinger Effect ◽  
Yield Criterion ◽  
Yield Function ◽  
Alloy Sheet ◽  
Spring Back ◽  
Bending Tests ◽  
Numerical Predictions ◽  
Draw Bending ◽  
Engineering Plasticity

Constitutive equations for plane stress problems based on the modified form of a non-quadratic yield criterion suitable for aluminium alloy sheet were derived to account for the Bauschinger effect (BE). Numerical predictions of spring-back based on the original yield function and its modified form were performed and compared with the results of draw-bending tests. The results show the necessity of including the BE in the constitutive equations to enhance the accuracy in predicting spring-back.

Forming Limit Analysis of Sheet Metals Based on a Generalized Deformation Theory

2003 ◽  
Vol 125 (3) ◽  
pp. 260-265 ◽  
Author(s):  
C. L. Chow ◽  
M. Jie ◽  
S. J. Hu
Keyword(s):  
Strain Hardening ◽  
Deformation Theory ◽  
Yield Criterion ◽  
Strain Ratio ◽  
Yield Function ◽  
Forming Limit ◽  
Sheet Metals ◽  
Theory Of Plasticity ◽  
Von Mises Yield Criterion ◽  
Von Mises

This paper presents the development of a generalized method to predict forming limits of sheet metals. The vertex theory, which was developed by Sto¨ren and Rice (1975) and recently simplified by Zhu, Weinmann and Chandra (2001), is employed in the analysis to characterize the localized necking (or localized bifurcation) mechanism in elastoplastic materials. The plastic anisotropy of materials is considered. A generalized deformation theory of plasticity is proposed. The theory considers Hosford’s high-order yield criterion (1979), Hill’s quadratic yield criterion and the von Mises yield criterion. For the von Mises yield criterion, the generalized deformation theory reduces to the conventional deformation theory of plasticity, i.e., the J2-theory. Under proportional loading condition, the direction of localized band is known to vary with the loading path at the negative strain ratio region or the left hand side (LHS) of forming limit diagrams (FLDs). On the other hand, the localized band is assumed to be always perpendicular to the major strain at the positive strain ratio region or the right hand side (RHS) of FLDs. Analytical expressions for critical tangential modulus are derived for both LHS and RHS of FLDs. For a given strain hardening rule, the limit strains can be calculated and consequently the FLD is determined. Especially, when assuming power-law strain hardening, the limit strains can be explicitly given on both sides of FLD. Whatever form of a yield criterion is adopted, the LHS of the FLD always coincides with that given by Hill’s zero-extension criterion. However, at the RHS of FLD, the forming limit depends largely on the order of a chosen yield function. Typically, a higher order yield function leads to a lower limit strain. The theoretical result of this study is compared with those reported by earlier researchers for Al 2028 and Al 6111-T4 (Grafand Hosford, 1993; Chow et al., 1997).

Springback Analysis of Aluminum Alloy Sheet Metals by Yoshida-Uemori Model

2016 ◽  
Vol 725 ◽  
pp. 566-571 ◽  
Author(s):  
Takeshi Uemori ◽  
Kento Fujii ◽  
Toshiya Nakata ◽  
Shinobu Narita ◽  
Naoya Tada ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Sheet Metal ◽  
Kinematic Hardening ◽  
Yield Function ◽  
Alloy Sheet ◽  
Aluminum Alloy Sheet ◽  
Sheet Metals ◽  
Initial Anisotropy ◽  
Hardening Rules ◽  
Prediction Capability

During the last few decades, the enhancement of prediction capability of the sheet metal forming have been increasing dramatically. High accurate yield criteria and wokhardening model (especially, non-linear kinematic hardening model) have a great importance for the prediction of the final shapes of sheet metal. However, the predicted springback accuracy of aluminum alloy sheet metal is not still good due to their complicated plastic deformation behaviors.In the present research, the springback deformation of aluminum alloy sheet metals were investigated by finite element calculation with consideration of initial anisotropy and the Bauschinger effect. In order to examine the effect of the initial and deformation induced anisotropy on the springback deformation, several types of high accurate yield function and hardening rules are utilized in the present research. The calculated springback by Yoshida 6th yield function [1] and Yoshida-Uemori model [2] shows an excellent agreement with the corresponding experimental data, while the other models underestimate the springback.

A Hybrid Membrane/Shell Method for Rapid Estimation of Springback in Anisotropic Sheet Metals

1998 ◽  
Vol 65 (3) ◽  
pp. 671-684 ◽  
Author(s):  
F. Pourboghrat ◽  
K. Chung ◽  
O. Richmond
Keyword(s):  
Plane Strain ◽  
Yield Criterion ◽  
Bending Moment ◽  
Isotropic Hardening ◽  
Normal Anisotropy ◽  
Bending Tests ◽  
Reverse Loading ◽  
Draw Bending ◽  
Springback Prediction ◽  
Good Agreement

A semi-analytical method to predict springback in sheet metal forming processes has been developed for the case of plane strain. In the proposed hybrid method, for each deformation increment, bending, and unbending stretches are analytically superposed on membrane stretches which are numerically obtained in advance from a membrane finite element code. Springback is then obtained by the unloading of a force and a bending moment at the boundary of each element treated as a shell. Hill’s 1948 yield criterion with normal anisotropy is used in this theory along with kinematic and isotropic hardening laws during reverse loading. The method has been applied for the springback prediction of a 2008-T4 aluminum alloy in plane-strain draw-bending tests. The results indicate the necessity of including anisotropic hardening (especially Bauschinger effects) and elastoplastic unloading in order to achieve good agreement with experimental results.

scholarly journals Bauschinger Effect on Springback of Clad Sheet Metals in Draw Bending

2010 ◽  
Vol 51 (7) ◽  
pp. 1364-1366 ◽  
Author(s):  
K. Yilamu ◽  
R. Hino ◽  
H. Hamasaki ◽  
F. Yoshida
Keyword(s):  
Bauschinger Effect ◽  
Sheet Metals ◽  
Clad Sheet ◽  
Draw Bending

Modified Swift Criteria for Residual Strength of Multiple Site Damage Structure

2009 ◽  
Vol 417-418 ◽  
pp. 881-884 ◽  
Author(s):  
Jian Yu Zhang ◽  
Rui Bao ◽  
Bin Jun Fei
Keyword(s):  
Residual Strength ◽  
Yield Criterion ◽  
Fatigue Cracks ◽  
Tensile Load ◽  
Maximum Load ◽  
Alloy Sheet ◽  
Multiple Cracks ◽  
Multiple Site ◽  
Multiple Site Damage ◽  
Aluminum Panels

As more aircrafts reach or exceed their design life, it is becoming very important to research multiple cracks damage, especially the multiple site damage (MSD) in order to re-evaluate their service life and damage tolerance/durability performance. The existing of MSD may remarkably reduce the residual strength of an aerospace structural component than those with a singe lead crack. This study investigated the residual strength of aluminum alloy sheet with MSD through three types of aluminum specimens test. Aluminum panels with bare collinear constant diameter holes were chosen as specimens. After some constant amplitude tension-tension load cycles, the MSD were found in these specimens since there were multiple fatigue cracks emanating from the saw cuts of holes. The residual strength was recorded as the maximum load when every specimen was subjected to monotonically increasing tensile load until failure occurred. In different failure prediction criteria that were often used in engineering in order to evaluate the accuracy of these criteria, Swift criterion (ligament yield) criterion got more accurate prediction results than other criteria. Although Swift criterion was more accurate than some other criteria, its error was still big for some specimens. Two modified approaches were proposed in order to get more accurate and appropriate failure criterion for MSD structure.

Numerical Analysis for Process Parameter Effect in Electromagnetic Impact Welding of Aluminum Alloy Sheet

2014 ◽  
Vol 548-549 ◽  
pp. 297-300
Author(s):  
Dae Yong Kim ◽  
Hyeon Il Park ◽  
Ji Hoon Kim ◽  
Sang Woo Kim ◽  
Young Seon Lee
Keyword(s):  
Aluminum Alloy ◽  
Numerical Analysis ◽  
Deformation Behavior ◽  
Three Dimensional ◽  
Alloy Sheet ◽  
Aluminum Alloy Sheet ◽  
Sheet Metals ◽  
Charge Voltage ◽  
Flat Sheet ◽  
Impact Welding

Studies on electromagnetic impact welding between similar or dissimilar flat sheet metals using the flat one turn coil have been recently achieved. In this study, three dimensional electromagnetic-mechanical coupled numerical simulations are performed for the electromagnetic impact welding of aluminum alloy sheets with flat rectangular one turn coil. The deformation behavior during impact welding was examined. The effect of process parameters such as charge voltage, standoff distance and gap distance were investigated.

scholarly journals Determining the material model at elevated temperatures with different strain rates and simulating the warm forming process for Mg alloy AZ31B sheet

2015 ◽  
Vol 18 (2) ◽  
pp. 149-158
Author(s):  
Thien Tich Truong ◽  
Long Thanh Nguyen ◽  
Binh Nguyen Thanh Vu ◽  
Hien Thai Nguyen
Keyword(s):  
Magnesium Alloy ◽  
Constitutive Equations ◽  
Elevated Temperatures ◽  
Material Model ◽  
Alloy Sheet ◽  
Strain Rates ◽  
Functional Requirements ◽  
Temperature Dependent ◽  
Forming Process ◽  
Az31b Alloy

Magnesium alloy is one of lightweight alloys has been studied more extensively today. Because weight reduction while maintaining functional requirements is one of the major goals in industries in order to save materials, energy and costs, etc. Its density is about 2/3 of aluminum and 1/4 of steel.The material used in this study is commercial AZ31B magnesium alloy sheet which includes 3% Al and 1% Zn. However, due to HCP (Hexagonal Close Packed) crystal structure, magnesium alloy has limited ductility and poor formability at room temperature. But its ductility and formability will be improved clearly at elevated temperature. From the data of tensile testing, the constitutive equations of AZ31B was approximated using the Ramgberg-Osgood model with temperature dependent parameters to fit in the experiment results in tensile test. Yield locus are also drawn in plane stress σ1- σ2 with different yield criteria such as Hill48, Drucker Prager, Logan Hosford, Y. W. Yoon 2013 and particular Barlat 2000 criteria with temperature dependent parameters. Applying these constitutive equations were determined at various temperatures and different strain rates, the finite element simulation stamping process for AZ31B alloy sheet by software PAM- STAMP 2G 2012, to verify the model materials and the constitutive equations.

A Yield Function for Anisotropic Sheet Material Described by 3rd-Degree Spline Curve and its Applications

2016 ◽  
Vol 725 ◽  
pp. 653-658 ◽  
Author(s):  
Toshiro Aamaishi ◽  
Hideo Tsutamori ◽  
Eiji Iizuka ◽  
Kentaro Sato ◽  
Yuki Ogihara ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Mild Steel ◽  
Plane Stress ◽  
Sheet Material ◽  
Yield Function ◽  
Sheet Metals ◽  
Anisotropic Behavior ◽  
Spline Curve ◽  
Series Aluminum Alloy

A new plane stress yield function using the 3rd-degree spline curve is proposed for the anisotropic behavior of sheet metals. This yield function considers the evolution of anisotropy in terms of both r values and stresses. In order to demonstrate the applicability of the proposed yield function, hole expanding tests with mild steel and 6000 series aluminum alloy sheets were simulated.

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