Simulation of Residual Stress Effect on Stress Corrosion Crack Growth in Gas Pipelines

2008 ◽  
Author(s):  
M. R. Fourozan ◽  
M. Olfatnia ◽  
S. J. Golestaneh
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Corrosion ◽  
Stress Corrosion Crack ◽  
Crack Growth ◽  
Crack Tip ◽  
Gas Pipelines ◽  
Stress Corrosion Crack Growth

In this paper, a quantitative study on stress corrosion crack growth in large diameter gas pipelines is presented. Finite element method is applied for determining stress intensity factor at the crack tip. First a small semi-elliptical axial surface crack is assumed. Then internal gas pressure and residual stress, induced from welding process, are considered. Applied forces and crack growth rate are calculated as a function of stress intensity factor based on an empirical equation. Crack front shape is determined by calculating stress intensity factor distributions along the crack tip. As a result, the effect of residual stress on stress intensity factor and therefore crack growth is determined. In addition, minimum crack size that activates the stress corrosion cracking mechanism is determined. It is shown that the applied method could be used to estimate the reliable life of pipeline and the suitable time for inspection of the pipeline’s surface.

Crack Tip Stress Analysis of the Steam Generator Dissimilar Steel Welded Joint under Residual Stress Field

2019 ◽  
Vol 795 ◽  
pp. 451-457
Author(s):  
Bao Yin Zhu ◽  
Xian Xi Xia ◽  
He Zheng ◽  
Guo Dong Zhang
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Field ◽  
Numerical Method ◽  
Steam Generator ◽  
Welded Joint ◽  
Crack Tip ◽  
Residual Stress Field

An typical mode of a structural integrity failure in dissimilar steel welded joints. This paper aims at studying crack tip stress of a steam generator dissimilar welded joint under residual stress field with the method of interaction integral and XFEM. Firstly, the corresponding weak form is obtained where the initial stress field is involved, which is the key step for the XFEM. Then, the interaction integral is applying to calculate the stress intensity factor. In addition, two simple benchmark problems are simulated in order to verify the precision of this numerical method. Finally, this numerical method is applying to calculate the crack tip SIF of the addressed problem. This study finds that the stress intensity factor increases firstly then decreases with the deepening of the crack. The main preponderance of this method concerns avoiding mesh update by take advantage of XFEM when simulating crack propagation, which could avoid double counting. In addition, our obtained results will contribute to the safe assessment of the nuclear power plant steam generator.

Modelling shattered rim cracking in railroad wheels

2011 ◽  
Vol 225 (6) ◽  
pp. 593-604
Author(s):  
V Sura ◽  
S Mahadevan
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Stress State ◽  
Intensity Factor ◽  
Residual Stresses ◽  
Equivalent Stress ◽  
Crack Tip ◽  
Residual Stress State

Shattered rim cracking, propagation of a subsurface crack parallel to the tread surface, is one of the dominant railroad wheel failure types observed in North America. This crack initiation and propagation life depends on several factors, such as wheel rim thickness, wheel load, residual stresses in the rim, and the size and location of material defects in the rim. This article investigates the effect of the above-mentioned parameters on shattered rim cracking, using finite element analysis and fracture mechanics. This cracking is modelled using a three-dimensional, multiresolution, elastic–plastic finite element model of a railroad wheel. Material defects are modelled as mathematically sharp cracks. Rolling contact loading is simulated by applying the wheel load on the tread surface over a Hertzian contact area. The equivalent stress intensity factor ranges at the subsurface crack tips are estimated using uni-modal stress intensity factors obtained from the finite element analysis and a mixed-mode crack growth model. The residual stress and wheel wear effects are also included in modelling shattered rim cracking. The analysis results show that the sensitive depth below the tread surface for shattered rim cracking ranges from 19.05 to 22.23 mm, which is in good agreement with field observations. The relationship of the equivalent stress intensity factor (Δ K eq) at the crack tip to the load magnitude is observed to be approximately linear. The analysis results show that the equivalent stress intensity factor (Δ K eq) at the crack tip depends significantly on the residual stress state in the wheel. Consideration of as-manufactured residual stresses decreases the Δ K eq at the crack tip by about 40 per cent compared to that of no residual stress state, whereas consideration of service-induced residual stresses increases the Δ K eq at the crack tip by about 50 per cent compared to that of as-manufactured residual stress state. In summary, the methodology developed in this article can help to predict whether a shattered rim crack will propagate for a given set of parameters, such as load magnitude, rim thickness, crack size, crack location, and residual stress state.

The Correction of Stress Intensity Factor for Crack Growth Evaluation Under Steep Residual Stress Distribution and Steep Yield Strength Distribution

2013 ◽  
Author(s):  
Tetsuo Yasuoka ◽  
Yoshihiro Mizutani ◽  
Akira Todoroki
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Stress Distribution ◽  
Intensity Factor ◽  
Yield Strength ◽  
Crack Tip ◽  
Strength Distribution ◽  
Residual Stress Distribution ◽  
Growth Evaluation

Welds and heat affected zones have the distribution of the residual stress or the yield strength. The crack growth evaluation is conventionally conducted using stress intensity factor in those regions. However, the stress intensity factor may be invalid when the residual stress distribution or yield strength distribution changes in the vicinity of a crack tip. The reason is that the distributions around the crack tip affect the plastic zone size and the stress intensity factor inappropriately represents the stress state in the vicinity of a crack tip. In this study, the residual stress distribution and yield strength distribution was assumed along the crack propagation path and the validity of the stress intensity factor was discussed on that condition. As a result, the stress intensity factor tended to be invalid when the steep residual stress distribution or the steep yield strength distribution. When the steep distribution exists, the crack growth evaluation should be conducted using a parameter considering the elastoplastic behavior near the crack tip. For that purpose, the authors proposed new method of the plastic zone correction using a differential term of the stress intensity factor. The new method was demonstrated through the case study for stress corrosion cracking of nuclear power plants.

Stress Intensity Factors due to Residual Stresses in Thin-Walled Girth-Welded Pipes

1981 ◽  
Vol 103 (1) ◽  
pp. 66-75 ◽  
Author(s):  
E. F. Rybicki ◽  
R. B. Stonesifer ◽  
R. J. Olson
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Stress Distribution ◽  
Intensity Factor ◽  
Crack Growth ◽  
Residual Stress Distribution ◽  
Intensity Factors ◽  
Thin Walled Pipe ◽  
Thin Walled

The effect of a girth-weld-induced residual stress field on the linear elastic fracture mechanics of a thin-walled pipe is examined. The procedure for using the residual stress distribution to compute KI and KII for a circumferential crack which is growing radially is described. In addition to the two-pass girth weld, stress intensity factors are computed for a residual stress distribution in a flat plate and for a hypothetical residual stress state in a second thin-walled pipe. The computed stress intensity factor for the flat plate geometry and its residual stress distribution are compared with a solution from the literature as a check on the computational procedure. The through-the-thickness residual stress distribution due to the two-pass girth weld is similar to a half-cosine wave. For purposes of comparison, the hypothetical through-the-thickness distribution selected for the second pipe is similar to a full cosine wave. The stress intensity factor is presented as a function of crack depth for a crack initiating on the inner surface of the pipe. The redistribution of residual stresses due to crack growth is also shown for selected crack lengths. The study shows that residual stress-induced crack growth in pipes can be significantly different from that in flat plates due to the possibility of locked-in residual bending moments in the pipe. These locked-in moments can have effects similar to externally applied loads and can either promote or restrain crack growth. A residual stress distribution is illustrated in which crack growth, if initiated, would continue through the entire wall. Also, a residual stress distribution is illustrated for which the crack could arrest after a certain amount of growth.

The Effects of Residual Stress Distribution and Component Geometry on the Stress Intensity Factor of Surface Cracks

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
Katsumasa Miyazaki ◽  
Masahito Mochizuki
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Stress Distribution ◽  
Intensity Factor ◽  
Stress Field ◽  
Crack Growth ◽  
Residual Stress Distribution ◽  
Surface Cracks ◽  
Intensity Factors

The stress intensity factor estimated by the appropriate modeling of components is essential for the evaluation of crack growth behavior in stress corrosion cracking. For the appropriate modeling of a welded component with a crack, it is important to understand the effects of residual stress distribution and the geometry of the component on the stress intensity factor of the surface crack. In this study, the stress intensity factors of surface cracks under two assumed residual stress fields were calculated. As residual stress field, a bending type stress field (tension-compression) and a self-equilibrating stress field (tension-compression-tension) through the thickness were assumed, respectively. The geometries of the components were plate and piping. The assumed surface cracks for those evaluations were a long crack in the surface direction and a semi-elliptical surface crack. In addition, crack growth evaluations were conducted to clarify the effects of residual stress distribution and the geometry of the component. Here, the crack growth evaluation means simulating increments of crack depth and length using crack growth properties and stress intensity factors. The effects of residual stress distribution and component geometry on the stress intensity factor of surface cracks and the appropriate modeling of cracked components are discussed by comparing the stress intensity factors and the crack growth evaluations for surface cracks under residual stress fields.

scholarly journals Fracture Mechanics Approach to Creep Crack Growth in Welded IN738LC Gas Turbine Blades

1991 ◽  
Author(s):  
Wan-P’ng Foo ◽  
Rafael Castillo
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Gas Turbine ◽  
Crack Growth ◽  
Turbine Blades ◽  
Creep Crack Growth ◽  
Crack Tip ◽  
Loading Conditions ◽  
Creep Crack

Microcracks caused by hot cracking or strain age cracking mechanisms are very likely to be discovered in the weld repair zone of precision cast IN738LC gas turbine blades. The possibility of crack propagation under the operating conditions of the gas turbine thereby becomes a crucial issue for gas turbine designers. The creep crack growth rate in air of the hipped and fully heat treated IN738LC was measured at the service temperature experienced by the first stage turbine blade tip. The corresponding growth behaviour was also studied. The creep crack growth rate, da/dt, versus crack tip stress intensity factor, K1, a relation which exhibits the typical primary, secondary and tertiary behaviour, supports the applicability of K1 as an appropriate correlating parameter for the creep crack growth of this Ni-based superalloy under the loading conditions used in this study. Microstructural examination illustrated that the creep crack growth of IN738LC principally takes place by the nucleation, growth, coalescence and link-up of grain boundary microvoids and microcracks. An excellent approximation of the stress intensity factor under service loading conditions in the vicinity of the crack tip was obtained by using the Westinghouse WECAN finite element analysis. It is shown that the crack tip stress intensity factor under normal loading conditions will not be able to drive the transverse through-the-wall-thickness blade tip crack in this study.

scholarly journals OS0827 Effect of Residual Stress Distribution on Evaluation of Stress Corrosion Crack Growth

2012 ◽  
Vol 2012 (0) ◽  
pp. _OS0827-1_-_OS0827-3_
Author(s):  
Fuminori IWAMATSU ◽  
Katsumasa MIYAZAKI ◽  
Toshiyuki SAITO ◽  
Tadahiro SHIBUTANI ◽  
Hideo KOBAYASHI
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Stress Corrosion ◽  
Stress Corrosion Crack ◽  
Crack Growth ◽  
Residual Stress Distribution ◽  
Stress Corrosion Crack Growth

Crack Growth Sensitivity to the Magnitude and Frequency of Load Fluctuation in Stage 1b of High pH Stress Corrosion Cracking

CORROSION ◽  
10.5006/3711 ◽  
2021 ◽  
Author(s):  
Hamid Niazi ◽  
Greg Nelson ◽  
Lyndon Lamborn ◽  
Reg Eadie ◽  
Weixing Chen ◽  
...  
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Initiation ◽  
Plastic Zone ◽  
Crack Propagation ◽  
Crack Growth ◽  
Crack Tip ◽  
Cyclic Plastic Zone ◽  
Secondary Cracks

Pipelines undergo sequential stages before failure caused by High pH Stress Corrosion Cracking (HpHSCC). These sequential stages are incubation stage, intergranular crack initiation (Stage 1a), crack evolution to provide the condition for mechanically driven crack growth (Stage 1b), sustainable mechanically driven crack propagation (Stage 2), and rapid crack propagation to failure (Stage 3). The crack propagation mechanisms in Stage 1b are composed of the nucleation and growth of secondary cracks on the free surface and crack coalescence of secondary cracks with one another and the primary crack. These mechanisms continue until the stress intensity factor (<i>K</i>) at the crack tip reaches a critical value, known as <i>K</i><sub>ISCC</sub>. This investigation took a novel approach to study Stage 1b in using pre-cracked Compact Tension (CT) specimens. Using pre-cracked specimens and maintaining <i>K</i> at less than <i>K</i><sub>ISCC</sub> provided an opportunity to study crack initiation on the surface of the specimen under plane stress conditions in the presence of a pre-existing crack. In the present work, the effects of cyclic loading characteristics on crack growth behavior during Stage 1b were studied. It was observed that the pre-existing cracks during Stage 1b led to the initiation of secondary cracks. The initiation of the secondary cracks at the crack tip depended on loading characteristics, <i>i.e</i>., the amplitude and frequency of load fluctuations. The secondary cracks at the crack tip can be classified into four categories based on their positions with respect to the primary crack. A high density of intergranular cracks formed in the cyclic plastic zone generated by low R-ratio cycles. The higher the frequency of the low <i>R</i>-ratio cycles, the higher the density of the intergranular cracks forming in the cyclic plastic zone. The crack growth rate increased with an increase in either the amplitude or the frequency of the load fluctuations. The minimum and maximum crack growth rates were 8×10<sup>-9</sup> mm/s and 4.2×10<sup>-7</sup> mm/s, respectively, with <i>R</i>-ratio varying between 0.2 and 0.9, frequency varying between 10<sup>-4</sup> Hz and 5×10<sup>-2</sup> Hz, and at a fixed stress intensity factor of 15 MPa.m<sup>0.5</sup>. It was found that avoiding rapid and large load fluctuations slowed down crack geometry evolution and delayed onset of Stage 2. The implication of these results for pipeline operators is that reducing internal pressure fluctuations by reducing the frequency and/or amplitude of the fluctuations can expand Stage 1 and increase the reliable lifetime of operating pipelines.

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