Effect of Weld Residual Stress Fitting on Stress Intensity Factor for Circumferential Surface Cracks in Pipe

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Do-Jun Shim ◽  
Steven Xu ◽  
Matthew Kerr
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Growth ◽  
Fourth Order ◽  
Surface Cracks ◽  
Weld Residual Stress ◽  
Order Polynomial ◽  
Fourth Order Polynomial

Recent studies have shown that the crack growth of primary water stress corrosion cracking (PWSCC) is mainly driven by the weld residual stress (WRS) within the dissimilar metal weld. The existing stress intensity factor (K) solutions for surface cracks in pipe typically require a fourth order polynomial stress distribution through the pipe wall thickness. However, it is not always possible to accurately represent the through thickness WRS with a fourth order polynomial fit and it is necessary to investigate the effect of the WRS fitting on the calculated Ks. In this paper, two different methods were used to calculate the K for a semi-elliptical circumferential surface crack in a pipe under a given set of simulated WRS. The first method is the universal weight function method (UWFM) where the through thickness WRS distribution is represented as a piece-wise monotonic cubic fit. In the second method, the through thickness WRS profiles are represented as a fourth order polynomial curve fit (both using the entire wall thickness data and only using data up to the crack-tip). In addition, three-dimensional finite element (FE) analyses (using the simulated weld residual stress) were conducted to provide a reference solution. The results of this study demonstrate the potential sensitivity of Ks to fourth order polynomial fitting artifacts. The piece-wise WRS representations used in the UWFM were not sensitive to these fitting artifacts and the UWFM solutions were in good agreement with the FE results. In addition, in certain cases, it was demonstrated that more accurate crack growth calculations of PWSCC are made when the UWFM is used.

Effect of Weld Residual Stress Fitting on Stress Intensity Factor for Circumferential Surface Cracks in Pipe

2012 ◽  
Author(s):  
Do-Jun Shim ◽  
Matthew Kerr ◽  
Steven Xu
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Wall Thickness ◽  
Stress Intensity Factors ◽  
Surface Cracks ◽  
Intensity Factors ◽  
Weld Residual Stress ◽  
Order Polynomial

Recent studies have shown that the crack growth of PWSCC is mainly driven by the weld residual stress (WRS) within the dissimilar metal weld. The existing stress intensity factor (K) solutions for surface cracks in pipe typically require a 4th order polynomial stress distribution through the pipe wall thickness. However, it is not always possible to accurately represent the through thickness WRS with a 4th order polynomial fit and it is necessary to investigate the effect of the WRS fitting on the calculated stress intensity factors. In this paper, two different methods were used to calculate the stress intensity factor for a semi-elliptical circumferential surface crack in a pipe under a given set of simulated WRS. The first method is the Universal Weight Function Method (UWFM) where the through thickness WRS distribution can be represented as a piece-wise cubic fit. In the second method, the through thickness WRS profiles are represented as a 4th order polynomial curve fit (both using the entire wall thickness data and only using data up to the crack-tip). In addition, three-dimensional finite element (FE) analyses (using the simulated weld residual stress) were conducted to serve as a reference solution. The results of this study demonstrate the potential sensitivity of stress intensity factors to 4th order polynomial fitting artifacts. The piece-wise WRS representations used in the UWFM was not sensitive to these fitting artifacts and the UWFM solutions were in good agreement with the FE results.

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.

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.

Stress Intensity Factor Solutions for Subsurface Flaws in Plates Subjected to Polynomial Stress Distributions

2016 ◽  
Author(s):  
Kai Lu ◽  
Jinya Katsuyama ◽  
Yinsheng Li ◽  
Fuminori Iwamatsu
Keyword(s):  
Stress Intensity Factor ◽  
Free Surface ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Distributions ◽  
Thickness Direction ◽  
Finite Element Analyses ◽  
Aspect Ratios ◽  
Order Polynomial ◽  
Fourth Order Polynomial

Stress intensity factor (SIF) solutions for subsurface flaws near the free surface in plates were numerically investigated based on the finite element analyses. The flaws with aspect ratios a/ℓ = 0, 0.1, 0.2, 0.3, 0.4 and 0.5, the normalized ratios a/d = 0, 0.1, 0.2, 0.4, 0.6 and 0.8 and d/t = 0.01 and 0.1 were taken into account, where a is the half flaw depth, ℓ is the flaw length, d is the distance from the center of the subsurface flaw to the nearest free surface and t is the wall thickness. Fourth-order polynomial stress distributions in the thickness direction were considered. Based on the results, it can be concluded that the numerical SIF solutions obtained in this study are useful in engineering applications.

Finite Element Analysis of the Stress Intensity Factor and the Residual Stress by Cold Expansion Method in CT Specimen

2006 ◽  
Vol 321-323 ◽  
pp. 711-715 ◽  
Author(s):  
Jae Soon Jang ◽  
Cheol Kim ◽  
Myoung Rae Cho ◽  
Won Ho Yang
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Initiation ◽  
Crack Growth ◽  
Expansion Method ◽  
Expansion Ratio ◽  
Cold Expansion

Cold expansion method retards the crack initiation due to the compressive residual stress developed on a hole surface. Most previous researches have shown only the beneficial distribution of residual stresses in the retardation of the crack initiation at the stress concentration area. Also, there have been only few studies on the relation between crack growth and residual stress around other adjacent holes. A few fastener holes of aircraft structures is a shot distance which is less than 20mm between holes. The purpose of this study is to provide better understanding of the residual stress effect around a hole in a structure as crack growth starts from another hole. By finite element method, this study showed that residual stress in a CT specimen is redistributed by cold expansion process and that tensile stress increases in proportion to the cold expansion ratio in the vicinity of the crack. Stress intensity factor increases as the cold expansion ratio increases.

Stress Intensity Factor Coefficients for Circumferential OD Surface Flaws in Cylinders for Appendix A of ASME Section XI

2018 ◽  
Author(s):  
Darrell R. Lee ◽  
Russell C. Cipolla ◽  
Michael C. Liu
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Closed Form ◽  
Fourth Order ◽  
Stress Distributions ◽  
Linear Elastic ◽  
Evaluation Procedures ◽  
Influence Coefficients ◽  
Weld Residual Stress

Linear elastic fracture mechanics based flaw evaluation procedures in Section XI of the ASME Boiler and Pressure Vessel Code require calculation of the stress intensity factor (KI). The 2015 Edition of ASME Section XI [1] implemented a number of significant improvements in Article A-3000, including closed-form equations for calculating stress intensity factor influence coefficients (Gi) for circumferential flaws on the inside surface of cylinders. In the 2017 Edition [2], closed-form equations for axial flaws on the inside and outside surfaces of cylinders have been implemented. In this paper, closed-form equations are developed for circumferential cracks on the OD surface of cylinders, based on tabular data from API 579 (2007 Edition) [3]. The equations presented, represent a complete set of Ri/t, a/t, and a/ℓ ratios. The closed-form equations provide G0 and G1 coefficients while G2 through G4 are obtained using a weight function representation for the KI solutions for a surface crack. These equations permit the calculation of the Gi coefficients without the need to perform tabular interpolation. The equations are complete up to a fourth order polynomial representation of the applied stress. The fourth-order representation for stress will allow for more accurate fitting of highly non-linear stress distributions, such as those depicting high thermal gradients and weld residual stress fields.

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.

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

2005 ◽  
Author(s):  
Katsumasa Miyazaki ◽  
Masahito Mochizuki
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Stress Distribution ◽  
Intensity Factor ◽  
Stress Field ◽  
Crack Growth ◽  
Surface Crack ◽  
Residual Stress Distribution ◽  
Intensity Factors

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

The Treatment of Residual Stress in Fracture Assessment of Pressure Vessels

1994 ◽  
Vol 116 (4) ◽  
pp. 345-352 ◽  
Author(s):  
D. Green ◽  
J. Knowles
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Pressure Vessels ◽  
Weld Residual Stress ◽  
Simple Rules ◽  
Fracture Assessment ◽  
Membrane Bending ◽  
Wall Components

The treatment of weld residual stress in the fracture assessment of cylindrical pressure vessels is considered through partitioning the stress into membrane, bending, and self-balancing through-wall components. The influence of each on fracture behavior is discussed. Stress intensity factor solutions appropriate to each type of stress are presented. Short-range, medium-range, and long-range stress categories are identified according to simple rules relating the effect of increasing crack length to stress intensity factor and ligament net stress. Proposals are made on how the stress intensity factor from these stress types may be incorporated into a Kr, Lr-based fracture assessment.

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