Metal Forming CAE Lab., Gyeongsang National University

1
???????? 2008?? ??????
ORMING
ETAL
???? ESW95? ??? ??? ?? ??
Metal Forming CAE Lab. Department of Mechanical
Engineering Gyeongsang National University, Korea
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E-mail msjoun_at_gnu.ac.kr
IMULATION
Metal Forming CAE Lab., Gyeongsang National
University
2
??
? ??
? ????
? ????? ?? ? ??(???, ?????)?? ??
? Hollomos law? ???
? ???????? ?????? ??
? ????-??? ?? ??
? ????ESW
? ESW95, ESW105, SCM435? ????
? ESW95, ESW105, SCM435? ???? ??
? ??? ????? ??? ????? ??
? ???? ?????? ??
? ???? ??????? ??
? ???? ???? ????? ?? 3, 4 stage
? ??? ???? ??????? ??
? ???? ???? ??? ??
? ??
3
??
? True stress-strain curve over large strain is
not easy to be acquired.
? Tensile Test(0.15 before the necking),
Compression Test(0.5), Spherical Indentation
Test(0.25)
? Recently several researchers have used the
finite element method to obtain the true
stress-strain curve. Cabezas and Celentano, 2004
Campitelli et al., 2004 Choi et al., 1997
Husain et al., 2004 Isselin et al., 2006 Lee et
al., 2005 Mirone, 2004 Nayebi et al., 2002
Springmann and Kuna, 2005
? Many researchers have tried to predict the
necking point in tensile test that meets the
Considère condition only to fail except Dumoulin
et al(2003). They used various imperfections
or constraints.
? To obtain the true stress-strain curve over
large strain by the tensile test the exact
prediction of the necking point is essential.
? ?? ??? ?? ???? ????? ????? ??? ????? ?? ????
??? ??? ??? ??? ?????
4
????
Tensile Test
? Mirone, G., 2004, "A New Model for the
Elastoplastic Characterization and the
Stress-Strain Determination on the Necking
Section of a Tensile Specimen," Int. J. Solids
Struct., Vol. 41, pp. 3545-3564.
? Zhang, K. S., 1995, "Fracture Predicition and
Necking Analysis," Eng. Fract. Mech., Vol. 52,
pp. 575-582.
? Komori, K., 2002, "Simulation of Tensile Test
by Node Separation Method," J. Mat. Proc. Tech.,
Vol. 125-126, pp. 608-612.
? Cabezas, E. E., Celentano, D. J., 2004,
"Experimental and Numerical Analysis of the
Tensile Test using Sheet Specimens, Fin. Ele.
Ana. Des., Vol. 40, pp. 555-575.
? Koc, P., ?tok, B., 2004, "Computer-Aided
Identification of the Yield Curve of a Sheet
Metal after Onset of Necking, Comp. Mat. Sci.,
Vol. 31, pp. 155-168.
? Bridgman, P. W., 1956, "Studies in Large Flow
and Fracture," McGraw-Hill.
? Zhang, Z. L., Hauge, M., Ødegård, J. and
Thaulow, C., 2001, "Determinating Material True
Stress-Strain Curve from Tensile Specimens with
Rectangular Cross-Section," Comp. Mat. Sci., Vol.
20, pp. 77-85.
Compression Test
? Lee, C. H., Altan, T., 1972, "Influence of Flow
Stress and Friction upon Metal Flow in Upset
Forging of Ring and Cylinders, ASME Trans., J.
Eng. Ind., Vol. 94, p. 782. .
? Osakada, K., Shiraishi, M., Muraki, S. and
Tokuoka, M., 1991, "Measurement of Flow Stress by
the Ring Compression Test, JSME Int. J.,
Series A, Vol. 34, NO. 3, pp. 312-318.
? Gelin, J. C., Ghouati, O., 1995, "The Inverse
Approach for the Determination of Constitutive
Equations in Metal Forming, Annals of CIRP,
Vol. 44, No. 1, pp. 189-192.
? Michino, M., Tanaka, M. and Kitaoka, T., 1996,
"Determination of Flow Stress by Inverse Analysis
Using FEM," J. JSPT, Vol. 37, No. 421, pp.
219-224.
? Choi, Y., Kim, B. M. and Choi, J. C., 1997, "A
Method of Determining Flow Stress and Friction
Factor by the Ring Compression Test", KSME
Spring Meeting, pp. 547-552.
? Haggag, F. M., Nanstad, R. K., Hutton, J. T.,
Thomas, D. L. and Swain, R. L., 1990, "Use of
Automated Ball Indentation Testing to Measure
Flow Properties and Estimate Fracture Toughness
in Metallic Materials," Application of Automation
Technology to Fatigue and Fracture Testing,
ASTM STP 1092, pp. 188-208.
5
????
Spherical Indentation Test
? Cheng, Y. T., Cheng, C. T., 1999, "Can
Stress-Strain Relationships Be Obtained from
Indentation Curves Using Conical and Pyramidal
Indenters?," J. Mater. Res., Vol. 14, pp.
3493-3496.
? Huber, N., Tsakmakis, C., 1999, "Determination
of Constitutive Properties from Spherical
Indentation Data Using Neural Networkings. Part
? the Case of Pure Kinematic Hardening in
Plasticity Laws," J. Mech. Phys. Solids, Vol. 47,
pp. 1569-1588.
? Huber, N., Tsakmakis, C., 1999, "Determination
of Constitutive Properties from Spherical
Indentation Data Using Neural Networkings. Part
? Plasticity with Nonlinear Isotropic and
Kinematic Hardening," J. Mech. Phys. Solids, Vol.
47, pp. 1589-1607.
? Nayebi, A., Abdi, R. El., Bartier, O. and
Mauvoisin, G., 2002, "New Procedure to Determine
Steel Mechanical Parameters from the Spherical
Indentation Technique," Mech. Materials, Vol. 34,
pp. 243-254.
? Lee, H., Lee, J. H. and Pharr, G. M., 2005, "A
Numerical Approach to Spherical Indentation
Techniques for Material Property Evaluation,"
J. Mech. Phy. Solids, Vol. 53, pp. 2037-2069.
Punch Test
? Campitelli, E. N., Spätig, P., Bonadé, R.,
Hoffelner, W. and Victoria, M., 2004, "Assessment
of the Constitutive Properties from Small Ball
Punch Test Experiment and Modeling," J. Nuclear
Materials, Vol. 335, pp. 366-378.
? Husain, A., Sehgal, D. K. and Pandey, R. K.,
2004, "An Inverse Finite Element Procedure for
the Determination of Constitutive Tensile
Behavior of Materials Using Miniature Specimen,"
Comp. Mat. Sci., Vol. 31, pp. 84-92.
? Isselin, J., Iost, A., Golel, J., Najjar, D.
and Bigerelle, M., 2006, "Assessment of the
Constitutive Law by Inverse Methodology Small
Punch Test and Hardness," J. Nuclear Materials,
in press.
Torsion Test
? Bressan, J. D., Unfer, R. K., 2006,
"Construction and Validation Tests of a Torsion
Test Machine," J. Mater. Proc. Tech., in press.
Notch Tensile Test
? Springmann, M., Kuna, M., 2005,
"Indentification of Material Parameters of the
Gurson-Tvergaard-Needleman Model by Combined
Experimental and Numerical Techniques," Comp.
Mat. Sci, Vol. 32, pp. 501-509.
6
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Flow stress
Flow stress
T / Tm
Strain rate
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Flow stress
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Strain rate
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7
Hollomons law? ???

• Hollomons law? ?? ??? ?????? ?????? ????? ???

• Hollomons law? ??? ??, ????? ??????? ??????
• ????? ???? ?. ??? ??????? ??? ??? ?? ???
• ??? ?? ??? ??(Computational Material science
  ?? ??)
• ???? ??

• Hollomons law?? ???? ??????, ? ??? ??? ??? ???.
• ??? Hollomons law? ?????, ? ????? ????? ???
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? ??????? ?? ? ?????? 10,951N ? ???
??? 3.386mm ? ?? ??? ?? ??
8
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? AFDEX/MAT? ????
? 1? ??? ????-??? ??
? ????? ?? ???
? AFDEX/MAT ???? ??? ???? ?? ????
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? 4? ??? ????-??? ??
3.0
2.0
? ???-?? ??? ????? ????? ??
Number of iterations Maximum error
0 30.29
1 6.04
2 3.96
3 0.89
4 0.28
10
?? ?? ESW
? ESW Energy Saver Wire, ????? ????, ??? ?
????? ???? ??
? ESW? ??? ???? ? ??? ??? ??? ??? ??????
???? ????? ???? ??? ???? ??
? ????
? ESW
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????? QT???
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???(???)??? ????? ?? ?????? ????? ??? ???? ????
11
?? ?? ESW
? ESW? ?? ??
???? ???? ???? kgf/mm2 ???? , GL5d ?????   ???? J, ?? ????
ESW75 7T 7080 15 ?? 60 ?? 100 ?? G/Rod
ESW85 8.8T 8090 15 ?? 60 ?? 100 ?? T/Rod, B/Stud ?
ESW95 9.8T 90100 15 ?? 60 ?? 100 ?? ????? ?
???? ??????? V???????
? ????? ??? SEM ???? ??
0.3 C? ???? ???? 850MPa
0.2 C? ESW85 ???? 850MPa
SCM435? ????? ?? ???? 500MPa
12
?? ?? ESW
? ESW ?? ??
Tie Rod
B/Stud
???? G/Rod
13
ESW95, ESW105, SCM435? ????
Specimen Yield Strength (N/mm2) Tensile Strength (N/mm2) Elongation ()
1 384.9 488.9 35.3
2 387.9 488.8 37.1
3 386.4 488.8 37.8
4 388.5 489.7 36.0
5 381.8 488.8 36.2
Table 1. Results of tensile test of SCM435
Specimen dimensions
Specimen Yield Strength (N/mm2) Tensile Strength (N/mm2) Elongation ()
1 962.4 995.0 16.4
2 947.7 991.2 16.2
3 940.1 983.9 16.0
4 947.5 993.4 16.0
5 960.3 987.6 16.6
Grip
Table 2. Results of tensile test of ESW95
14
ESW95, ESW105, SCM435? ????? ??
? Tensile load-elongation curves
? True stress-strain curves
AFDEX/MAT
15
??? ????? ??? ????? ??
16
???? ?????? ??
ltSCM435gt
ltESW95gt
ltESW105gt
17
???? ??????? ?? Effective strain
SCM435
ESW95
ESW105
18
???? ???? ?? ?? (3 stage)? ??
19
???? ???? ?? ?? (4 stage)? ??
20
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21
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22
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? ????? ?? ???? ?? ???? ??? AFDEX/MAT? ??? ?? ???
?? ????? ???? ??? ?? ???? ????? ??? ???. ?
???? ESW95? ESW105? ??????? ??? ??? ?? ??,
????? ?? ?? ??? ????. ? ??? ????? ?? ??? ????
ESW95? ?????? ??? ??? ? ??, ??? ??? ????? ??
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