0
Materials and Fabrication

Equivalent CTOD Ratio β for Engineering Assessment of CTOD Correction for Constraint Loss

[+] Author and Article Information
Mitsuru Ohata

Division of Materials and Manufacturing Science, Graduate School of Engineering,  Osaka University, 2–1 Yamada-Oka, Suita, Osaka 565–0871, Japanohata@mapse.eng.osaka-u.ac.jp

Fumiyoshi Minami

Division of Materials and Manufacturing Science, Graduate School of Engineering,  Osaka University, 2–1 Yamada-Oka, Suita, Osaka 565–0871, Japanminami@mapse.eng.osaka-u.ac.jp

J. Pressure Vessel Technol 134(5), 051403 (Sep 10, 2012) (8 pages) doi:10.1115/1.4006346 History: Received June 01, 2011; Revised March 05, 2012; Published September 10, 2012; Online September 10, 2012

The critical CTOD δWP for structural components associated with plastic constraint loss in case of the brittle fracture over small-scale yielding condition can be corrected from CTOD fracture toughness δ by means of the “equivalent CTOD ratio β” defined as δ/δWP , which is based on the Weibull stress criterion. In this study, taking the case of specific wide plate components subjected to uni-axial tensile load, the effect on β is analyzed taking account of Weibull shape parameter m, loading level, constraint effect that can be influenced by material work-hardening and crack type/size in structural components, etc., and volumetric effect. It is found that the β-value is almost constant beyond the applied CTOD level that is lower than CTOD of small-scale yielding limit (SSY-limit) for 25 mm thick toughness specimen. From an engineering point of view, the β-value at the CTOD level of 0.01 mm is used in the whole loading range beyond SSY-limit CTOD, which provides to some extent conservative measure of fracture toughness of structural components. The defined β is found to decrease with increasing Weibull shape parameter m and yield-to-tensile ratio YR of steel for all type of wide plates concerned. The crack length effect on β is quasi-theoretically formulated, which can convert the β for the wide plate with reference crack size to β for target crack size. These β and quasi-theoretical equations for the correction of crack size effect can be utilized for estimating the CTOD for wide plate in consideration of constraint loss effect without numerical calculation of the Weibull stress.

FIGURES IN THIS ARTICLE
<>
Copyright © 2012 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Equivalent CTOD ratio β based on the Weibull stress criterion for constraint loss correction

Grahic Jump Location
Figure 2

Wide plate components of concern (a) CSCP, (b) ESCP, (c) CTCP, and (d) ETCP

Grahic Jump Location
Figure 3

Comparison between Weibull stress as a function of CTOD for a three-point bend and a compact specimen. (a) YR = 0.60, (b) YR = 0.82, and (c) YR = 0.95.

Grahic Jump Location
Figure 4

Effect of a0 /W on Weibull stress σW and equivalent CTOD ratio β. (a) Weibull stress σW and (b) equivalent CTOD ratio β.

Grahic Jump Location
Figure 5

Equivalent CTOD ratio as a function of CTOD of standard fracture toughness specimen (a) CSCP (2c = 16 mm, a = 6 mm), (b) ESCP (2c = 24 mm, a = 3 mm), (c) CTCP (2a = 7.4 mm), and (d) ETCP (2a = 5.8 mm)

Grahic Jump Location
Figure 6

Effect of yield-to-tensile ratio YR on equivalent CTOD ratio β for CSCP (a) CSCP (2c = 40 mm, a = 1 mm), (b) CSCP (2c = 40 mm, a = 3 mm), and (c) CSCP (2c = 40 mm, a = 6 mm)

Grahic Jump Location
Figure 7

Sensitivity of yield-to-tensile ratio YR to difference between σW for the three-point bend specimen and the wide plate (CSCP: 2c = 40 mm, a = 6 mm)

Grahic Jump Location
Figure 8

Effect of crack length 2c on equivalent CTOD ratio β for CSCP (a = 6 mm) (a) YR = 0.60, (b) YR = 0.82, and (c) YR = 0.95

Grahic Jump Location
Figure 9

Crack opening stress σyy ahead of the crack tip at the center of surface crack in CSCP with different crack length 2c (YR = 0.82)

Grahic Jump Location
Figure 10

Normalized b for CSCP with crack length 2c by that with 2c = 40 mm (a) YR = 0.60 and (b) YR = 0.95

Grahic Jump Location
Figure 11

Verification of formulated equation to estimate the effect of crack length on β for CSCP (a = 6 mm) (a) YR = 0.60 and (b) YR = 0.95

Grahic Jump Location
Figure 12

Comparison between the equivalent CTOD ratio β in IST method [9] and constraint correction parameter adopted in the FITNET [12] for CTCP specimen

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