Implications of the yield stress/tensile stress ratio to the SINTAP failure assessment diagrams for homogeneous materials

Huh

2005

JSME Int. J., Ser. A

The present work presents a method to estimate elastic-plastic J for circumferential through-wall cracked pipes for the Leak-Before-Break (LBB) analysis of pressurized piping. The proposed method is based on the GE/EPRI approach and the key issue is to propose a robust Ramberg-Osgood fitting procedure. Two different estimation schemes are given, one for the case when full stress-strain data are available, and the other for the case when only yield and ultimate tensile strengths are available. The proposed J estimates are compared with those from extensive elastic-plastic finite element (FE) analyses. Experimental validation is also performed by comparing maximum moments predicted by fracture mechanics analysis using the proposed J estimates with those from full-scale pipe test. Both results show sufficient confidence in the accuracy of the proposed J estimates.

Section: Proposed R-o Fit For the Ge/epri Approach -When Only Yieldmentioning

confidence: 99%

Engineering J Estimation Methods for Leak-Before-Break Analyses of Nuclear Piping

Huh

2005

JSME Int. J., Ser. A

“…(8), and thus the problem remains how to estimate n. It should be reminded that for accurate J estimates, the value of n should be based on engineering stress-strain data, instead of true stress-strain data. Figure 2 (a) shows 1/n values as a function of σ y /σ u , determined from the power law fit to engineering stress-strain data for various materials (18), (19) . Before developing an estimation equation for n from σ y /σ u , one point is worth noting.…”

Section: Cod Estimates Based On Ge/epri Approachmentioning

confidence: 99%

“…(17) or Eq. (18) with 1/n values, determined from the power law fit to true stress-strain data for various materials (18), (19) . Equation (18) is also compared with 1/n values from the power law fit to engineering stress-strain data for the same materials in Fig.…”

Section: Cod Estimates Based On Reference Stress Approachmentioning

confidence: 99%

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Engineering Leak-Before-Break Analyses of Pressurized Piping: Part I- Crack Opening Displacement

Huh

et al. 2004

JSME Int. J., Ser. A

The present work presents methods to estimate elastic-plastic COD for circumferential through-wall cracked pipes for the Leak-Before-Break analysis of pressurized piping. Proposed methods are based not only on the GE/EPRI approach but also on the reference stress approach. For each approach, two different estimation schemes are given, one for the case when full stress-strain data are available, and the other for the case when only yield and ultimate tensile strengths are available. For the GE/EPRI approach, a robust way of determining the R-O parameters is proposed, not only for the case when detailed information on full stress-strain data are available but also for the case when only yield and ultimate tensile strengths are available. The COD estimates according to the GE/EPRI approach, using the R-O parameters determined from the proposed R-O fitting procedures, overall compare well with the published pipe test data. For the reference stress approach, the COD estimates according to the method based both on full stress-strain data and on limited tensile properties are in good agreement with pipe test data. In conclusion, experimental validation given in the present work provides sufficient confidence in the use of the proposed method to practical LBB analyses, even when information on material's tensile properties is limited.

The Journal of Strain Analysis for Engineering Design

“…Apart from Table 1, other studies have reported (C)WP tests without mentioning the specimen geometry. 26,27 Considering the above, (C)WP specimen geometry and the positions of remote strain sensors should be consciously considered prior to performing an experimental program. This paper summarizes a feasibility study of a new specimen design, summarized in Table 2, based on experimentally validated finite element results.…”

Section: Introductionmentioning

confidence: 99%

Investigation of strain measurements in (curved) wide plate specimens using digital image correlation and finite element analysis

Hertelé

Waele

Denys

et al. 2012

Some pipelines face global plastic straining due to the nature of their installation process or harsh environmental conditions during operation. The ability of the girth welds to withstand these plastic strains is often evaluated on the basis of wide plate tests. Key for the validity of these tests is a representative measurement of remote strain, mostly obtained by linear variable differential transformers and/or strain gauges. The outcome of the remote strain measurement depends on the specimen geometry and the position of these sensors. In an attempt to investigate a specific geometric design of wide plate specimens and to find appropriate remote strain sensor positions, the authors have performed a series of tension tests on medium-sized wide plate specimens, supported by digital image correlation strain measurements. In addition, finite element simulations have been performed to evaluate whether the experimental observations can be extrapolated to a wider range of conditions. The results indicate that the strain distribution is mostly influenced by the weld strength mismatch, which governs the lateral restraint. For all experiments and simulations, nevertheless, the strain field was highly uniform in an identified zone, resulting in simple guidelines regarding specimen geometry and sensor positioning.