An inverse identification technique is proposed based on bending-unbending experiments on anisotropic sheet-metal strips. The initial anisotropy theory of plasticity is extended to include the concept of combined isotropic and nonlinear kinematic hardening. This theory is adopted to characterize the anisotropic hardening due to loading-unloading which occurs in sheet-metals forming processes. To this end, a specific bending-unbending apparatus has been built to provide experimental moment-curvature curves. The constant bending moment applied over the length of the specimen allows one to determine numerically the strain-stress behavior but without Finite Element Analysis. Four constitutive parameters have been identified by an inverse approach performed simultaneously on the bending and tensile tests. Our identification results show that bending-unbending tests are suitable to model quite accurately the constitutive behavior of sheet metals under complex loading paths.

Issue Section:
Technical Papers
Keywords:
work hardening, bending, kinematics, forming processes, plasticity, stress-strain relations, metals
Topics:
Anisotropy, Hardening, Kinematics, Sheet metal, Stress, Plasticity, Strips
1.
Mattiasson, A., Strange, P., Thilderkvist, A., and Samuelsson, 1995, “Simulation of Springback in Sheet Metal Forming,” 5th International Conference on Numerical Methods in Industrial Forming Process, New York, pp. 115–124.
2.
Li, K., and Wagoner, R. H., 1998, “Simulation of Springback,” Simulation of Materials Processing: Theory, Methods and Applications, NUMIFORM’98 Huetink and Baaijens, eds., Enschede, Netherlands, pp. 21–31.
3.
Tang, S. C., 1996, “Application of an Anisotropic Hardening Rule to Springback Prediction,” Advanced Technology of Plasticity, pp. 719–722.
4.
Chaboche
,
J. L.
,
1977
, “
Viscoplastic Constitutive Equation for the Description of Cyclic and Anisotropic Behaviour of Metals
,”
Bulletin Acade´mique Polonais. des Sciences
,
25
, pp.
33
–
47
.
5.
Lemaitre J., and Chaboche, J. L., 1990, Mechanic of Solid Materials, Cambridge University Press, Cambridge, U.K.
6.
Hill, R., 1948, “A Theory of the Yielding and Plastic Flow of Anisotropic Metals,” Proc. R. Soc. London, Ser. A, pp. 281–297.
7.
Hill
,
R.
,
1990
, “
Constitutive Modelling of Orthotropic Plasticity in Sheet Metals
,”
J. Mech. Phys. Solids
,
38
, pp.
405
–
417
.
8.
Zhang
,
Z. T.
, and
Lee
,
D.
,
1995
, “
Development of a new model for plane strain bending and springback analysis
,”
J. Mater. Eng. Perform.
,
4
, pp.
291
–
300
.
9.
Hiwatashi
,
S.
,
Van-Bael
,
A.
,
Van-Houtte
,
P.
, and
Teodosiu
,
C.
,
1997
, “
Modeling of plastic anisotropy based on texture and dislocation structure
,”
Computational Materials Science
,
9
, pp.
274
–
284
.
10.
Zhao, K. M., and Lee, J. K., 1999, “On Simulation of Bend/Reverse Bend of Sheet metals,” MED-Vol. 10, Manufacturing Science and Engineering, ASME 1999, pp. 929–933.
11.
Brunet
,
M.
,
Mguil-Touchal
,
S.
, and
Morestin
,
F.
,
1998
, “
Analytical and Experimental Studies of Necking in Sheet Metal Forming Processes
,”
J. Mater. Process. Technol.
,
80–81
, pp.
40
–
46
.
12.
Norton, J. P., 1986, An Introduction to Identification, Academic Press, San Diego, CA.
13.
Mahnken
,
R.
, and
Stein
,
E.
,
1996
, “
A Unified Approach for Parameter Identification of Inelastic Materials Models in the Frame of the Finite Element Method
,”
Comput. Methods Appl. Mech. Eng.
,
136
, pp.
225
–
258
.
Copyright © 2001
 by ASME
You do not currently have access to this content.