Estimation of Stress Intensity Factors due To Welding Residual Stresses for Circumferentially Cracked Pipes

2012 ◽  
Author(s):  
Chang-Young Oh ◽  
Ji-Soo Kim ◽  
Yun-Jae Kim ◽  
Young-Jin Oh ◽  
Kyoungsoo Lee ◽  
...  
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Residual Stresses ◽  
Stress Intensity Factors ◽  
Finite Element Analyses ◽  
Intensity Factors ◽  
Crack Face ◽  
Simple Method ◽  
Weld Geometry ◽  
Nonlinear Stress

This paper proposes a simple method to estimate stress intensity factors due to welding residual stresses. In this study, finite element analyses for circumferentially cracked pipe are performed to calculate stress intensity factors. Four cracked geometries and two types of weld geometry are considered. KI-solutions for the nonlinear stress distribution on the crack face were determined in accordance with codes and standards. The results are compared with KI-solutions from finite element results. It is found that proposed simple method agrees well with FE results.

Residual Stress Redistribution Caused by Notches and Cracks in a Partially Autofrettaged Tube

1981 ◽  
Vol 103 (4) ◽  
pp. 302-306 ◽  
Author(s):  
S. L. Pu ◽  
M. A. Hussain
Keyword(s):  
Residual Stress ◽  
Stress Intensity ◽  
Residual Stresses ◽  
Stress Intensity Factors ◽  
Classical Method ◽  
Thermal Simulation ◽  
Intensity Factors ◽  
Crack Face ◽  
Simple Method ◽  
Crack Configuration

A simple method is provided for the computation of the redistribution of residual stresses and the stress intensity factors due to the introduction of notches and cracks in a partially autofrettaged tube. Numerical results of several crack and notch problems are obtained by the method of thermal simulation. These results are shown to be in excellent agreement with those obtained from the classical method of superposition. The new method based on thermal simulation is easier to apply and it avoids the alternate method of superposition requiring cumbersome distributed crack face loadings for each crack configuration.

A Method for Assessing the “Local” Accuracy of Weight Functions for Plates With Embedded Cracks

1995 ◽  
Author(s):  
S. W. Ng ◽  
K. J. Lau
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Weight Functions ◽  
Finite Element Analyses ◽  
Intensity Factors ◽  
Local Accuracy ◽  
New Algorithms

Abstract In this paper a procedure is developed to assess the “local” accuracy of weight functions for finding stress intensity factors of centrally cracked finite plates given by Tsai and Ma (1989). It is found that the weight functions can be used to calculate stress intensity factors for practical cases, with “local” accuracy being within 6 %. In addition, weight functions generated from two finite element analyses are found to be accurate and may be used to assess new algorithms for finding weight functions.

scholarly journals Stiffness Derivative Finite Element Technique to Determine Nodal Weight Functions With Singularity Elements

1983 ◽  
Author(s):  
George T. Sha
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Crack Tip ◽  
Weight Functions ◽  
Two Dimensional ◽  
Intensity Factors ◽  
Crack Face ◽  
Crack Geometry ◽  
Crack Problems

The use of the stiffness derivative technique coupled with “quarter-point” singular crack-tip elements permits very efficient finite element determination of both stress intensity factors and nodal weight functions. Two-dimensional results are presented in this paper to demonstrate that accurate stress intensity factors and nodal weight functions can be obtained from relatively coarse mesh models by coupling the stiffness derivative technique with singular elements. The principle of linear superposition implies that the calculation of stress intensity factors and nodal weight functions with crack-face loading, σ(rs), is equivalent to loading the cracked body with remote loads, which produces σ(rs) on the prospective crack face in the absence of crack. The verification of this equivalency is made numerically, using the virtual crack extension technique. Load independent nodal weight functions for two-dimensional crack geometry is demonstrated on various remote and crack-face loading conditions. The efficient calculation of stress intensity factors with the use of the “uncracked” stress field and the crack-face nodal weight functions is also illustrated. In order to facilitate the utilization of the discretized crack-face nodal weight functions, an approach was developed for two-dimensional crack problems. Approximations of the crack-face nodal weight functions as a function of distance, (rs), from crack-tip has been successfully demonstrated by the following equation: h a , r s = A a √ r s + B a + C a √ r s + D a r s Coefficients A(a), B(a), C(a) and D(a), which are functions of crack length (a), can be obtained by least-squares fitting procedures. The crack-face nodal weight functions for a new crack geometry can be approximated using cubic spline interpolation of the coefficients A, B, C and D of varying crack lengths. This approach, demonstrated on the calculation of stress intensity factors for single edge crack geometry, resulted in a total loss of accuracy of less than 1%.

The evaluation of stress intensity factors for plane cracks in residual stress fields

1993 ◽  
Vol 28 (3) ◽  
pp. 145-152 ◽  
Author(s):  
M D B Wilks ◽  
D Nowell ◽  
D A Hills
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Intensity ◽  
Residual Stresses ◽  
Crack Closure ◽  
Efficient Method ◽  
Stress Intensity Factors ◽  
Stress Fields ◽  
Intensity Factors ◽  
Distributed Dislocations

A reliable, efficient method is described for modelling plane cracks in arbitary residual stress fields, using the technique of distributed dislocations. This allows correctly for re-distribution of residual stresses as the crack grows. Problems where crack closure occur are discussed, and implications for solution by finite element procedures are inferred and confirmed by comparison.

Computations of Stress Intensity Factors for Deep Cracks in Plates by Using the Tetrahedral Finite Element

2012 ◽  
Author(s):  
Hiroshi Okada ◽  
Hirohito Koya ◽  
Hiroshi Kawai ◽  
Yinsheng Li
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Residual Stresses ◽  
Stress Intensity Factors ◽  
Structural Integrity ◽  
Intensity Factors ◽  
Welded Structures ◽  
Elliptical Cracks

In this paper, stress intensity factor solutions for deep half-elliptical cracks that are applicable to the structural integrity evaluations of welded structures are presented. Welded structures generally have some weld residual stresses resulting in stress corrosion crackings (SCCs). This paper describes a simple way to compute the stress intensity factors under the weld-residual stresses and the mode I stress intensity factor solutions for deep half-elliptical cracks. The residual stresses are set to vary proportional to the constant, the linear, the quadratic and the cubic functions of x which is the distance from the plate surface. Although we use a straightforward finite element method to perform the computations, we can quickly generate the stress intensity factor solutions as we make use of automatic mesh generation program for the tetrahedral finite element. Thus, it is very tractable to generate the finite element models with cracks. Furthermore, present solutions can be compared with those of Li et al. which are also presented in PVP 2012. We conclude that present method is useful for the evaluations of SIFs of cracks under the residual stresses.

DETERMINATION OF RESIDUAL STRESSES AND STRESS INTENSITY FACTORS BY REMOVING LOCAL MATERIAL

2017 ◽  
Vol 48 (4) ◽  
pp. 377-398
Author(s):  
Svyatoslav Igorevich Eleonskii ◽  
Igor Nikolaevich Odintsev ◽  
Vladimir Sergeevich Pisarev ◽  
Stanislav Mikhailovich Usov
Keyword(s):  
Stress Intensity ◽  
Residual Stresses ◽  
Stress Intensity Factors ◽  
Intensity Factors ◽  
Local Material
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