Reference stress based J estimation formula for cracked cylinders with a wide range of radius-to thickness ratios: Part II- circumferential surface cracks

2020 ◽  
Vol 187 ◽  
pp. 104176
Author(s):  
Jae-Min Gim ◽  
Ji-Su Shin ◽  
Yun-Jae Kim
Keyword(s):  
Surface Cracks ◽  
Estimation Formula ◽  
Reference Stress ◽  
Wide Range ◽  
J Estimation

scholarly journals On the Calculation of Stress Intensity Factors and J-Integrals Using the Submodeling Technique

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Eduard Marenić ◽  
Ivica Skozrit ◽  
Zdenko Tonković
Keyword(s):  
Stress Intensity ◽  
Limit Load ◽  
Analytical Approximation ◽  
J Integral ◽  
Surface Cracks ◽  
Linear Elastic ◽  
Reference Stress ◽  
Wide Range ◽  
Reference Pressure ◽  
Axial Surface

In the present paper, calculations of the stress intensity factor (SIF) in the linear-elastic range and the J-integral in the elastoplastic domain of cracked structural components are performed by using the shell-to-solid submodeling technique to improve both the computational efficiency and accuracy. In order to validate the submodeling technique, several numerical examples are analyzed. The influence of the choice of the submodel size on the SIF and the J-integral results is investigated. Detailed finite element solutions for elastic and fully plastic J-integral values are obtained for an axially cracked thick-walled pipe under internal pressure. These values are then combined, using the General Electric/Electric Power Research Institute method and the reference stress method, to obtain approximate values of the J-integral at all load levels up to the limit load. The newly developed analytical approximation of the reference pressure for thick-walled pipes with external axial surface cracks is applicable to a wide range of crack dimensions.

scholarly journals Improved J Estimation by GE/EPRI Method for the Thin-Walled Pipes With Small Constant-Depth Circumferential Surface Cracks

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
X. Liu ◽  
Z. X. Lu ◽  
Y. Chen ◽  
Y. L. Sui ◽  
L. H. Dai
Keyword(s):  
Influence Functions ◽  
J Integral ◽  
Surface Cracks ◽  
Constant Depth ◽  
Long Distance ◽  
Small Constant ◽  
Wide Range ◽  
Thin Walled ◽  
Plastic Influence Functions ◽  
J Estimation

Application of thin-walled high strength steel has become a trend in the oil and gas transportation system over long distance. Failure assessment is an important issue in the construction and maintenance of the pipelines. This work provides an engineering estimation procedure to determine the J-integral for the thin-walled pipes with small constant-depth circumferential surface cracks subject to the tensile loading based upon the General Electric/Electric Power Research (GE/EPRI) method. The values of elastic influence functions for stress intensity factor and plastic influence functions for fully plastic J-integral are derived in tabulated forms through a series of three-dimensional (3D) finite element (FE) calculations for a wide range of crack geometries and material properties. Furthermore, the fit equations for elastic and plastic influence functions are developed, where the effects of crack geometries are explicitly revealed. The new influence functions lead to an efficient J estimation and can be well applied for structural integrity assessment of thin-walled pipes with small constant-depth circumferential surface cracks under tension.

Development of Z-Factor for Circumferential Part-Through Surface Cracks in Dissimilar Metal Welds

2008 ◽  
Author(s):  
D.-J. Shim ◽  
G. M. Wilkowski ◽  
D. L. Rudland ◽  
F. W. Brust ◽  
Kazuo Ogawa
Keyword(s):  
Correction Factor ◽  
Carrying Capacity ◽  
Limit Load ◽  
Maximum Load ◽  
Load Carrying Capacity ◽  
Surface Cracks ◽  
Crack Driving Force ◽  
Dissimilar Metal ◽  
Load Carrying ◽  
J Estimation

Section XI of the ASME Code allows the users to conduct flaw evaluation analyses by using limit-load equations with a simple correction factor to account elastic-plastic fracture conditions. This correction factor is called a Z-factor, and is simply the ratio of the limit-load to elastic-plastic fracture mechanics (EPFM) maximum-load predictions for a flaw in a pipe. The past ASME Section XI Z-factors were based on a circumferential through-wall crack in a pipe rather than a surface crack. Past analyses and pipe tests with circumferential through-wall cracks in monolithic welds showed that the simplified EPFM analyses (called J-estimation schemes) could give good predictions by using the toughness, i.e., J-R curve, of the weld metal and the strength of the base metal. The determination of the Z-factor for a dissimilar metal weld (DMW) is more complicated because of the different strength base metals on either side of the weld. This strength difference can affect the maximum load-carrying capacity of the flawed pipe by more than the weld toughness. Recent work by the authors for circumferential through-wall cracks in DMWs has shown that an equivalent stress-strain curve is needed in order for the typical J-estimation schemes to correctly predict the load carrying capacity in a cracked DMW. In this paper, the Z-factors for circumferential surface cracks in DMW were determined. For this purpose, a material property correction factor was determined by comparing the crack driving force calculated from the J-estimation schemes to detailed finite element (FE) analyses. The effect of crack size and pipe geometry on the material correction factor was investigated. Using the determined crack-driving force and the appropriate toughness of the weld metal, the Z-factors were calculated for various crack sizes and pipe geometries. In these calculations, a ‘reference’ limit-load was determined by using the lower strength base metal flow stress. Furthermore, the effect of J-R curve on the Z-factor was investigated. Finally, the Z-factors developed in the present work were compared to those developed earlier for through-wall cracks in DMWs.

J-Integral Analysis of Surface Cracks in Round Bars under Bending Moments

2011 ◽  
Vol 52-54 ◽  
pp. 43-48 ◽  
Author(s):  
Al Emran Ismail ◽  
Ahmad Kamal Ariffin ◽  
Shahrum Abdullah ◽  
Mariyam Jameelah Ghazali ◽  
Ruslizam Daud
Keyword(s):  
Finite Element ◽  
Crack Depth ◽  
Crack Tip ◽  
Bending Moment ◽  
Limit Load ◽  
Fe Model ◽  
Surface Cracks ◽  
Element Analysis ◽  
Reference Stress ◽  
Proposed Model

This paper presents a non-linear numerical investigation of surface cracks in round bars under bending moment by using ANSYS finite element analysis (FEA). Due to the symmetrical analysis, only quarter finite element (FE) model was constructed and special attention was given at the crack tip of the cracks. The surface cracks were characterized by the dimensionless crack aspect ratio, a/b = 0.6, 0.8, 1.0 and 1.2, while the dimensionless relative crack depth, a/D = 0.1, 0.2 and 0.3. The square-root singularity of stresses and strains was modeled by shifting the mid-point nodes to the quarter-point locations close to the crack tip. The proposed model was validated with the existing model before any further analysis. The elastic-plastic analysis under remotely applied bending moment was assumed to follow the Ramberg-Osgood relation with n = 5 and 10. J values were determined for all positions along the crack front and then, the limit load was predicted using the J values obtained from FEA through the reference stress method.

Selecting Suitable Probes Distances for Sizing Deep Surface Cracks Using the DCPD Technique

2006 ◽  
Vol 129 (1) ◽  
pp. 205-210 ◽  
Author(s):  
Fumio Takeo ◽  
Masumi Saka ◽  
S. Reaz Ahmed ◽  
Seiichi Hamada ◽  
Manabu Hayakawa
Keyword(s):  
Three Dimensional ◽  
Potential Drop ◽  
Surface Cracks ◽  
Deep Surface ◽  
Input And Output ◽  
Wide Range ◽  
Current Input ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
The Way

In this study, the way to enhance the sensitivity of evaluating deep surface cracks by DCPD technique using four probes is considered. The potential drops across two-dimensional cracks having different depths are analyzed by the three-dimensional finite-element method. The effect of the distance between current input and output probes and the distance between measuring probes on the change in potential drops are analyzed for a wide range of crack depths. By extending the distance between current input and output probes, the change in potential drop with the change in the depth of deeper crack becomes large. But the voltage of potential drop becomes small to measure. Finally, the way to select the appropriate distances between the probes for the measuring sensor is shown from the viewpoints of sensitivity and the required current.

Recent Advances for J Simplified Assessment in RSE-M Code

2003 ◽  
Author(s):  
Bruno Michel ◽  
Jean-Philippe Sermage ◽  
Philippe Gilles ◽  
Bruno Barthelet ◽  
Patrick Le Delliou
Keyword(s):  
Large Scale ◽  
Surface Defects ◽  
Complex Loading ◽  
Limit Load ◽  
Assessment Method ◽  
Reactor Power ◽  
Pressurized Water ◽  
Reference Stress ◽  
Recent Advances ◽  
Wide Range

The RSE-M Code [1] provides rules and requirements for in-service inspection of French Pressurized Water Reactor power plant components. Non mandatory guidance is given in the Code for analytical flaw evaluation in a wide range of situations. In Appendix 5.4 of the Code, influence coefficients are provided to calculate stress intensity factors in pipes and shells containing semi-elliptical surface defects. The J assessment method is based on the reference stress concept with two options for reference loads evaluation: “CEP elastic plastic stress” and “CLC modified limit load”. In this paper recent advances concerning J assessment under mechanical loading for a crack located in a pipe-elbow junction are presented. Reference stress evaluation with “CLC” option is developed and mechanical foundations of the equation of large scale yielding under complex loading (pressure, in-plane and out-of-plane bending) are presented.

Engineering J Estimation Equations for Spent Fuel Canisters Under Combined Mechanical and Welding Residual Stresses

2018 ◽  
Author(s):  
Hyun-Jae Lee ◽  
Jae-Yoon Jeong ◽  
Yun-Jae Kim ◽  
Poh-Sang Lam
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Fe Analysis ◽  
Welding Residual Stress ◽  
Spent Fuel ◽  
Basic Form ◽  
Estimation Equations ◽  
Reference Stress ◽  
J Estimation

This paper provides engineering J estimation equations for Spent Fuel Canisters (SFCs) under combined mechanical and welding residual stress (WRS) fields. The basic form of estimation equations is reference stress-based ones as in R6. Interaction between mechanical (primary) and residual (secondary) stresses is treated using the V-factor. Based on systematic finite element (FE) analysis and J results, the V-factors for the combined mechanical and welding residual stresses are reported.

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