The results of fatigue tests are characterized by much scatter. Such scatter is further increased if data from different test series are combined to derive, for instance, characteristic values for individual types of welded joints used in codes. Characteristic values are normally applied to the design of fatigue-resistant ship and offshore structures in connection with the nominal stress approach using S-N curves. More advanced approaches such as the hot-spot stress approach and the notch stress approach are applied to an increasing extent. Such approaches explicitly consider certain influence factors and allow the scatter of these factors to be treated individually. This way, probably even the total uncertainty can be reduced. After reviewing the different approaches used for fatigue strength assessment, the sources of scatter are addressed and assigned to factors considered in the different approaches. Based on published data of fatigue tests and imperfections observed in real structures, an attempt is made to quantify the uncertainties of the different factors and to draw conclusions for their individual consideration in the approaches mentioned.

Issue Section:
Research Papers
Topics:
Fatigue strength, Modeling, Uncertainty, Electromagnetic scattering, Stress, Fatigue testing, Design, Fatigue, Offshore structures, Ships, Welded joints
1.
Almar-Naess, A. Ed., 1985, Fatigue Handbook—Offshore Steel Structures, Tapir Publ., Trondheim, Norway.
2.
American Petroleum Institute, 1982, APIRP 2A—Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms, 13th Edition.
3.
Berge
S.
, and
Myhre
H.
,
1977
, “
Fatigue Strength of Misaligned Cruciform and Butt Joints
,”
Norwegian Maritime Research
, Vol.
5
, No.
1
, pp.
29
–
39
.
4.
Department of Energy, 1990, Offshore Installations: Guidance on Design and Construction and Certification, 4th Edition.
5.
Fricke, W., and Petershagen, H., 1992, “Detail Design of Welded Ship Structures Based on Hot-Spot Stresses,” 5th International Conference on Practical Design of Ships and Mobile Units, Newcastle upon Tyne, U.K.
6.
Germanischer Lloyd, 1990, Rules for the Classification and Construction. Offshore Technology, Part 2,—“Offshore Installations,” Chap. 2,” Hamburg, Germany.
7.
Germanischer Lloyd, 1997, Rules and Regulations, I—Ship Technology, Part 1—Seagoing Ships, Chap. 1 “Hull Structures,” Hamburg, Germany.
8.
Gurney, T. R., 1976, “Fatigue Design Rules for Welded Steel Joints,” Welding Research Bulletin, Vol. 17.
9.
Haibach, E., 1989, “Fatigue Strength—Methods and Data for the Analysis of Structural Components” (in German), VDI-Verlag GmbH, Du¨sseldorf, Germany.
10.
IIW, 1996, Fatigue Design of Welded Joints and Components, The International Institute of Welding, ed., A. Hobbacher, Abington Publishing, Cambridge, U.K.
11.
Ko¨ttgen, V. B., Olivier, R., and Seeger, T., 1991, “Fatigue Strength Analysis of Welded Joints on the Basis of Local Stresses” (in German), DVS-Symposium EXPERT ’91, DVS-Report 133, Deutscher Verlag fu¨r Schweilßtechnik, Du¨sseldorf, Germany.
12.
Kozliakov, V. V., 1992, “An Analysis of Structural Peculiarities and Causes of Severe Hull Damages of Bulkcarriers, Tankers and OBO-Ships,” RINA International Conference on Tankers and Bulk Carriers—The Way Ahead, London, U.K.
13.
Lawrence, F. V., Mattos, J. R., et al., 1978, “Estimating the Fatigue Crack Initiation Life of Welds,” Fatigue Testing of Weldments, ASTM STP 648, pp. 134–158.
14.
Maddox, S. J., 1985, “Fitness for Purpose Assessment of Misalignment in Transverse Butt Welds Subject to Fatigue Loading,” IIW-Doc. XIII-1180-85, International Institute of Welding.
15.
Matoba, M., Kawasaki, T., et al., 1983, “Evaluation of Fatigue Strength of Welded Steel Structures—Hull’s Members, Hollow Section Joints, Piping and Vessel Joints,” IIW-Doc. XIII-1082-83, International Institute of Welding.
16.
Neuber, H., 1968, “On the Consideration of Stress Concentrations in Strength Analyses” (in German), Konstruktion, Vol. 20.
17.
Niemi, E., 1992, “Recommendations Concerning Stress Determination for Fatigue Analysis of Welded Components,” IIW-Doc. XIII-1458-92/XV-797-92, International Institute of Welding.
18.
Olivier, R., and Ritter, W., 1979/82, “Catalogue of S-N Curves of Welded Joints in Structural Steel,” DVS-Report 56, Vol. 1–5, Deutscher Verlag fu¨r Schweilßtechnik, Du¨sseldorf, Germany.
19.
Olivier, R., and Seeger, T., 1989, “The Effect of Weld Toe Angle on Fatigue Strength of Welded Joints—Unified Evaluation of Published Test Results” (in German), FG Werkstoffmechanik of TH Darmstadt, Report FF-2-1989.
20.
Radaj, D., 1985, “Notch Stress Proof for Fatigue Resistant Welded Structures,” IIW-Doc. XIII-1157-85, International Institute of Welding.
21.
Radaj, D., 1990, Design and Analysis of Fatigue-Resistant Welded Structures, Abington Publishing, Cambridge.
22.
Yoneya, T., Kumano, A., et al., 1993, “Hull Cracking of Very Large Ship Structures,” Proceedings, 5th International Symposium on Integrity of Offshore Structures, Glasgow, Scotland.
This content is only available via PDF.
Copyright © 1998
 by The American Society of Mechanical Engineers
You do not currently have access to this content.