0
RESEARCH PAPERS

Meaning of Ke in Design-by-Analysis Fatigue Evaluation

[+] Author and Article Information
Gerry C. Slagis

 G C Slagis Associates, 258 Hillcrest Place, Pleasant Hill, California 94523slagisg@asme.org

The quoted Ref. 6 is Ref. 5 in this document.

From unpublished committee documents.

J. Pressure Vessel Technol 128(1), 8-16 (Oct 26, 2005) (9 pages) doi:10.1115/1.2140798 History: Received September 09, 2005; Revised October 26, 2005

The ASME Section III Design-by-Analysis rules for pressure-retaining components include a detailed fatigue evaluation based on elastically predicted primary, secondary, and peak stresses. A prerequisite for the fatigue analysis is that the primary-plus-secondary stress range does not exceed 3Sm. If this limit is exceeded, the code provides “Simplified Elastic-Plastic Analysis” rules for the fatigue evaluation. A Ke penalty factor is applied to the elastically predicted alternating stress. The maximum value of Ke (3.3 or 5) is a severe design limitation. Test data indicate that the code specified maximum value of Ke is very conservative. The simplified elastic-plastic rules were originally developed for piping and published in B31.7. When the piping rules were incorporated into Section III in 1971, the B31.7 procedure was replaced by a less complex procedure. The development of the simplified elastic-plastic analysis approach is reviewed to establish the technical basis for the present code rules. The concepts of fatigue, shakedown to elastic action, thermal bending, elastic follow-up, notch factor, and strain redistribution are discussed. Recommendations for changes to the plastic strain correction factor are provided.

FIGURES IN THIS ARTICLE
<>
Copyright © 2006 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

NB-3200 stress limits (2004)

Grahic Jump Location
Figure 2

Shakedown to elastic action

Grahic Jump Location
Figure 3

Plastic redistribution (Figs. 1 and 2 from Ref. 7)

Grahic Jump Location
Figure 4

B31.7 Appendix F correction factor for plastic strain redistribution

Grahic Jump Location
Figure 5

Langer’s configurations for plastic strain analysis (from Ref. 5)

Grahic Jump Location
Figure 6

Selection of Ke as 1∕n (from Ref. 5)

Grahic Jump Location
Figure 7

Gerber test specimens (from Ref. 9)

Grahic Jump Location
Figure 8

Gerber fatigue test data (from Ref. 9)

Grahic Jump Location
Figure 9

Ke Data (from Ref. 10)

Grahic Jump Location
Figure 10

Krempl test specimen

Grahic Jump Location
Figure 11

Carbon steel Ke data (from Ref. 7)

Grahic Jump Location
Figure 12

Piping design examples

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In