Effect of anisotropic yield function evolution on formability of sheet metal

2017 ◽  
Author(s):  
H. J. Choi ◽  
Y. Choi ◽  
K. J. Lee ◽  
J. Y. Lee ◽  
K. Bandyopadhyay ◽  
...  
Keyword(s):  
Sheet Metal ◽  
Yield Function ◽  
Anisotropic Yield Function

Wrinkling of an Unevenly Stretched Sheet Metal

1989 ◽  
Vol 111 (3) ◽  
pp. 235-242 ◽  
Author(s):  
Xiaofang Wang ◽  
L. H. N. Lee
Keyword(s):  
Finite Element Method ◽  
Sheet Metal ◽  
Strong Influence ◽  
Flexural Rigidity ◽  
Plastic Material ◽  
Yield Function ◽  
Material Parameters ◽  
Varying Thickness ◽  
Anisotropic Yield Function ◽  
Elastic Plastic Material

The onset of wrinkling of an unevenly stretched sheet metal subject to finite deformation is analyzed by an incremental finite element method. The sheet metal is modeled as a plate made of an elastic-plastic material. Hill’s anisotropic yield function and bifurcation criterion are employed in the analysis. The effects of geometrical and material parameters upon the onset of wrinkling are investigated. In the bifurcation analysis, attention is given to the changing and varying thickness of the sheet metal which could have a strong influence on the flexural rigidity of the sheet. Numerical results are presented herein.

Determination of Anisotropy Parameters via the Optimization Process of V-Bending

2015 ◽  
Author(s):  
F. Ozturk ◽  
S. Toros
Keyword(s):  
Sheet Metal ◽  
High Strength ◽  
Optimization Methods ◽  
Optimization Method ◽  
Yield Function ◽  
Bulge Test ◽  
Model Parameters ◽  
Anisotropic Yield Function ◽  
Anisotropy Parameters ◽  
The Difference

In recent years, the use of optimization methods in sheet metal forming has been increased remarkably. In the finite element simulation of the sheet metal stamping operations, the model parameters are determined from the several tests like tensile, compression, and biaxial stretching tests (bulge test). In this study, Yld2000-2d anisotropic yield function parameters are determined for DP800 advanced high strength steel using a 60° V-shaped die bending process. The difference between the simulation and experiment is found to be 1 degree using the classical determination method of the anisotropy parameters. The difference is 0.1 degree using the optimization method.

Effect of Material Frame Rotation on the Hardening of an Anisotropic Material in Simple Shear Tests

2018 ◽  
Vol 85 (12) ◽  
Author(s):  
Kelin Chen ◽  
Stelios Kyriakides ◽  
Martin Scales
Keyword(s):  
Simple Shear ◽  
Plastic Anisotropy ◽  
Yield Function ◽  
Strain Response ◽  
Shear Tests ◽  
Stress Strain ◽  
Anisotropic Yield Function ◽  
Torsion Experiment ◽  
Thin Walled Tube ◽  
Material Frame

The shear stress–strain response of an aluminum alloy is measured to a shear strain of the order of one using a pure torsion experiment on a thin-walled tube. The material exhibits plastic anisotropy that is established through a separate set of biaxial experiments on the same tube stock. The results are used to calibrate Hill's quadratic anisotropic yield function. It is shown that because in simple shear the material axes rotate during deformation, this anisotropy progressively reduces the material tangent modulus. A parametric study demonstrates that the stress–strain response extracted from a simple shear test can be influenced significantly by the anisotropy parameters. It is thus concluded that the material axes rotation inherent to simple shear tests must be included in the analysis of such experiments when the material exhibits anisotropy.

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