Analysis of the laser forming process has been focused on geometry, yield strength, and microstructure change in the past. However fatigue life has been the primary concern for engineering components in many applications. For laser forming to become a practical rapid prototyping tool, research has to be done to predict fatigue life of sheet metal after laser forming. Microstructure as well as the distribution of residual stresses and strains changes during laser forming process. The current models cannot predict the fatigue life after laser forming accurately because of differences in assumptions. This work presents a model to predict fatigue life of sheet metal after laser forming. Results from microstructure integrated finite element modeling of laser forming are incorporated in the fatigue life model. Low carbon steel is used in this work to validate the model. It is shown that the proposed model can predict the fatigue life of sheet metal after laser forming with good accuracy. The predictions from the model are consistent with experimental results. Effects of laser forming conditions on fatigue life of sheet metal are under investigation.

Issue Section:
Technical Papers
Keywords:
carbon steel, laser materials processing, sheet metal processing, forming processes, fatigue testing, fatigue, internal stresses, crystal microstructure, finite element analysis
Topics:
Fatigue life, Lasers, Fatigue testing, Modeling, Stress
1.
Thomson
,
G.
, and
Pridham
,
M.
,
2001
, “
Material Property Changes Associated with Laser Forming of Mild Steel Components
,”
J. Mater. Process. Technol.
,
118
, pp.
40
–
44
.
2.
Chen
,
G. F.
,
Xu
,
X. F.
,
Poon
,
C. C.
, and
Tan
,
A. C.
,
1998
, “
Laser-Assisted Microscale Deformation of Stainless Steels and Ceramics.
”
Neuropsychobiology
,
37
(
10
), pp.
2837
–
2842
.
3.
Merklei
,
M.
,
Hennige
,
T.
, and
Geiger
,
M.
,
2001
, “
Laser Forming of Aluminum and Aluminum Alloys–Microstructural Investigation
,”
J. Mater. Process. Technol.
,
115
, pp.
159
–
165
.
4.
Maher, W., 1998, “Laser Forming of Titanium and other Materials is Usable Within Metallurgical Constraints,” Proceedings of ICALEO’ 98, Section E, Orlando, FL, pp. 121–129.
5.
Fruhauf
,
J.
,
Gartner
,
E.
, and
Jansch
,
E.
,
1999a
, “
Silicon as a Plastic Material
,”
J. Micromech. Microeng.
,
9
(
4
), pp.
305
–
312
.
6.
Fruhauf
,
J.
,
Gartner
,
E.
, and
Jansch
,
E.
,
1999b
, “
New Aspects of the Plastic Deformation of Silicon—Prerequisites for the Reshaping of Silicon Microelements
,”
Appl. Phys. A: Mater. Sci. Process.
,
68
, pp.
673
–
679
.
7.
Hsiao, Y., Shimizu, H., Firth, L., Maher, W., and Masubuchi, K., , 1997, “Finite Element Modeling of Laser Forming,” Proceedings of ICALEO’97, Section A, San Diego, CA, pp. 31–40.
8.
Magee
,
J.
,
Watkins
,
K. G.
, and
Steen
,
W. M.
,
1998
, “
Advances in Laser Forming
,”
J. Laser Appl.
,
10
(
6
), pp.
235
–
246
.
9.
Bao, J., and Yao, Y. L., 1999, “Study of Edge Effects in Laser Bending,” Proc. ASME IMECE 1999, Symposium on Advanced in Metal Forming, Nashville, TN, Vol. Med-10, pp. 941–948.
10.
Li
,
W.
, and
Ya
,
Y. L.
,
2000
, “
Numerical and Experimental Study of Strain Rate Effects in Laser Forming
,”
ASME J. Manuf. Sci. Eng.
,
122
, pp.
445
–
451
.
11.
Li
,
W.
, and
Yao
,
Y. L.
,
2001
, “
Laser Bending of Tubes: Mechanism, Analysis and Prediction
,”
ASME J. Manuf. Sci. Eng.
,
123
, pp.
674
–
681
.
12.
Cheng
,
J.
, and
Yao
,
Y. L.
,
2002
, “
Y. Microstructure Integrated Modeling of Multiscan Laser Forming
,”
J. Manuf. Sci. Eng.
,
124
, pp.
379
–
387
.
13.
Goodman, J., 1930, Mechanics Applied to Engineering, Longmans, London, Vol. 1, 9th ed.
14.
Lessels, J. M., 1954, Strength and Resistance of Matals, Wiley, New York.
15.
Soderberg
,
C. R.
,
1930
, “
Factor of Safety and Working Stress
,”
Trans. Am. Soc. Test Matls.
,
52
(
2
), pp.
13
–
28
.
16.
Morrow, J. D., 1965, ASTM STP 378 (American Society for Testing and Materials).
17.
Basquin
,
O. H.
1910
, “
The Exponential Law of Endurance Tests
,”
Proc. ASTM.
,
10
, pp.
625
–
630
.
18.
Tavernelli
,
J. F.
, and
Coffin
, Jr.,
L. F..
,
1962
, “
Experimental Support for Generalized Equation Predicting Low Cycle Fatigue
,”
Trans. ASME, J. Basic Eng.
,
84
(
4
), pp.
533
–
541
.
19.
Manson, S. S., 1966, Thermal Stress and Low Cycle Fatigue, New York, McGraw-Hill.
20.
Smith
,
K. N.
,
Watson
,
P.
, and
Topper
,
T. H.
,
1970
, “
Stress-Strain Function for the Fatigue of Metals
,”
J. Mater.
,
5
(
4
), pp.
767
–
778
.
21.
Gong
,
Y.
, and
Norton
,
M.
,
1999
, “
Cyclic Response and Fatigue of Steels Subjected to Strain Control with Non-Zero means
,”
J. Testing and Evaluation
,
27
, pp.
15
–
30
.
22.
Boyer, H. E., and Gray, A. G., 1977, Atlas of Isothermal Transformation and Cooling Transformation Diagrams, American Society for Metals.
Copyright © 2005
 by ASME
You do not currently have access to this content.