Approximate J Estimates for Circumferential Cracks in between Elbows and Attached Pipes

2007 ◽  
Vol 345-346 ◽  
pp. 521-524
Author(s):  
Tae Kwang Song ◽  
Chang Kyun Oh ◽  
Yun Jae Kim ◽  
Jong Sung Kim ◽  
Tae Eun Jin
Keyword(s):  
Finite Element ◽  
Fracture Mechanics ◽  
Closed Form ◽  
Limit Load ◽  
Small Strain ◽  
Straight Pipe ◽  
Popular Approach ◽  
Elastic Plastic ◽  
Reference Stress ◽  
Mechanics Analysis

The present work proposes a method for elastic-plastic fracture mechanics analysis of the circumferential through-wall crack in between elbows and attached straight pipes, subject to in-plane bending. Based on small strain finite element limit analyses, closed-form limit load solutions are given first. Then applicability of the reference stress based method to approximately estimate J is proposed. One interesting finding is that a popular approach to assume that the crack locates in the straight pipe could lead to significantly different assessment results.

Estimates of Plastic Limit Loads of Thick-Walled Cylinders With Non-Idealzied Through-Wall Cracks

2013 ◽  
Author(s):  
Tae-Song Han ◽  
Nam-Su Huh ◽  
Do-Jun Shim
Keyword(s):  
Fracture Mechanics ◽  
Structural Integrity ◽  
Limit Load ◽  
Ductile Material ◽  
J Integral ◽  
Plastic Limit ◽  
Limit Loads ◽  
Elastic Plastic ◽  
Reference Stress ◽  
Plastic Limit Load

In order to assess a structural integrity of cracked components made of highly ductile material based on fully plastic fracture mechanics concept, an accurate plastic limit load of components of interest is crucial element. Such a plastic limit load can also be applied to estimate elastic-plastic J-integral based on the reference stress concept. In this context, during last several decades, many efforts have been made to suggest plastic limit load solutions of cracked cylinder. Recent works for evaluating rupture probabilities of nuclear piping indicate that the only use of idealized circumferential through-wall crack leads to very conservative results which in turn gives higher rupture probabilities of nuclear piping, thus the considerations of more realistic crack shape during crack growth due to primary water stress corrosion cracking (PWSCC) and fatigue and axial through-wall crack were recommended to come up with more realistic rupture probabilities of nuclear piping. Then, the needs of fracture mechanics parameters of non-idealized through-wall cracks both in axial and circumferential directions have been raised. In the present work, the plastic limit loads of thick-walled cylinder with non-idealized axial and circumferential through-wall cracks are proposed based on detailed 3-dimensional finite element analyses. The present results can be applied either to assess structural integrity of thick-walled nuclear piping with non-idealized through-wall cracks or to calculate elastic-plastic J-integral using the reference stress concept.

scholarly journals Elastic-plastic fracture mechanics analysis by combination of boundary element and finite element methods.

1984 ◽  
Vol 50 (460) ◽  
pp. 1963-1971 ◽  
Author(s):  
Kikuo KISHIMOTO ◽  
Ishou YAMAGUCHI ◽  
Masayoshi TACHIHARA ◽  
Shigeru AOKI ◽  
Masaru SAKATA
Keyword(s):  
Finite Element ◽  
Fracture Mechanics ◽  
Boundary Element ◽  
Finite Element Methods ◽  
Elastic Plastic ◽  
Mechanics Analysis

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.

K Value Calculation of Central Crack Plane Using FRANC2D

2012 ◽  
Vol 215-216 ◽  
pp. 762-765 ◽  
Author(s):  
Da Long Ren ◽  
Shui Wan ◽  
Zhi Peng Zhong
Keyword(s):  
Finite Element ◽  
Fracture Mechanics ◽  
Satisfactory Result ◽  
Calculation Result ◽  
Grid Size ◽  
Coarse Grid ◽  
Crack Plane ◽  
K Value ◽  
Central Crack ◽  
Mechanics Analysis

Abstract: FRANC2D is compared with the finite element programs and professional finite element programs for fracture mechanics analysis, and its processof fracture mechanics analysis is showed. By central crack plane,the fessibility of FRANC2D is used to calculate value is verified; different grid thickness model results is researched, which showed the grid size has little effect on the calculation result, and a coarse grid moel may get satisfactory result.

Effects of Torsion on Equivalent Bending Moment for Limit Load and EPFM Circumferential Pipe Flaw Evaluations

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Phuong H. Hoang ◽  
Kunio Hasegawa ◽  
Bostjan Bezensek ◽  
Yinsheng Li
Keyword(s):  
Finite Element ◽  
Pressure Vessel ◽  
Large Strain ◽  
Bending Moment ◽  
Limit Load ◽  
Elastic Plastic ◽  
Perfectly Plastic ◽  
Plastic Materials ◽  
Weighted Factor ◽  
Elastic Perfectly Plastic

The circumferential flaw evaluation procedures in ASME Boiler and Pressure Vessel Code Section XI nonmandatory Appendix C are currently limited to straight pipes under pressure and bending loads without consideration of torsion loading. The Working Group on Pipe Flaw Evaluation of the ASME Boiler and Pressure Vessel Code is developing guidance for considering the effects of torsion by a mean of an equivalent bending moment, which is a square root of sum square combination of bending moment and torsion load with a weighted factor for torsion moment. A torsion weighted factor, Ce, is established in this paper using large strain finite element limit load analysis with elastic perfectly plastic materials. Planar flaws and nonplanar flaws in a 10.75 in. (273 mm) OD pipe are investigated. Additionally, a finite element J-integral calculation is performed for a planar through wall circumferential flaw with elastic plastic materials subjected to bending and torsion load combinations. The proposed Ce factor for planar flaws is intended for use with the ASME B&PV Code Section XI, Appendix C for limit load and Elastic Plastic Fracture Mechanics (EPFM) circumferential planar flaw evaluations.

scholarly journals Elastic-plastic fracture mechanics analysis using wavelet Galerkin method

2014 ◽  
Vol 80 (819) ◽  
pp. CM0333-CM0333
Author(s):  
Shuya UEDA ◽  
Satoyuki TANAKA ◽  
Shogo SANNOMARU ◽  
Shigenobu OKAZAWA ◽  
Hiroshi OKADA
Keyword(s):  
Fracture Mechanics ◽  
Galerkin Method ◽  
Elastic Plastic ◽  
Wavelet Galerkin Method ◽  
Mechanics Analysis
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