scholarly journals Nonplanar Crack Growth Simulation of Multiple Cracks Using Finite Element Method

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Yahya Ali Fageehi ◽  
Abdulnaser M. Alshoaibi
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Growth ◽  
Source Code ◽  
Circumferential Stress ◽  
Adaptive Mesh ◽  
Propagation Mechanism ◽  
Multiple Cracks

This work deals with a 2D finite element simulation of nonplanar multiple cracks using fracture and crack propagation analysis. This analysis was performed by using the developed source code software written by Visual Fortran Language. This source code includes the adaptive mesh generation utilizing the advanced front method and also the mesh refinement process. In order to correctly represent the field singularity, the quarter-point singular elements are constructed around the tip of the crack. The crack growth criteria are used to predict the crack growth direction by utilizing the circumferential stress factor in calculating the yielding stress in elastic fracture assumptions. The stress intensity factor determination is one of the most critical procedures as it determines the crack initiation and propagation mechanism. Moreover, the stress intensity factor histories during the crack growth are measured with the use of equivalent domain integral methods. The crack path simulation and stress intensity factor calculations are compared with the literature and revealed that the results are in agreement with research carried in this domain.

Computation of Stress Intensity Factor for Multiple Cracks Using Singular Finite Element

2011 ◽  
Vol 214 ◽  
pp. 75-79 ◽  
Author(s):  
Ruslizam Daud ◽  
Ahmad Kamal Ariffin ◽  
Shahrum Abdullah ◽  
Al Emran Ismail ◽  
A. Zulkifli
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Analytical Solution ◽  
Crack Width ◽  
Width Ratio ◽  
Multiple Cracks ◽  
Two Dimensional ◽  
Interval Ratio

The simplification of two dimensional approaches in singular finite elements has promoted the method to be used in the formulation of stress intensity factor (SIF) of multiple cracks in finite body. The effect of shielding and amplification are considered in defining the SIF. As been observed, the current available analytical approximations are more restricted to several assumptions. The more accurate and less restricted method has motivated this study. This paper presents the investigation of singular finite elements applied in two dimensional finite element models subjected to different crack-width ratio and cracks interval ratio. The newly finite element formulations are resulted with good agreement with theoretical statement compared to analytical solution. The weak points of presented analytical solution are discussed regards to the influence of crack width ratio and cracks interval ratio.

Review of Technical Basis for ASME Code Section XI Appendix L

2020 ◽  
Author(s):  
Deepak S. Somasundaram ◽  
Dilip Dedhia ◽  
Do Jun Shim ◽  
Gary L. Stevens ◽  
Steven X. Xu
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Intensity Factor ◽  
Crack Growth ◽  
Multiple Cracks ◽  
Single Crack ◽  
Flaw Tolerance ◽  
Asme Code ◽  
The Impact

Abstract Equivalent Single Crack (ESC) sizes are provided in ASME Code, Section XI, Nonmandatory Appendix L, Tables L-3210-1 (for ferritic piping) and L-3210-2 (for austenitic piping). These two tables define initial flaw aspect ratios for use in fatigue flaw tolerance evaluations. These ESC sizes were based on the results of probabilistic fracture mechanics (PFM) evaluations that determined the equivalent single crack size that resulted in the same probability of through-wall leakage as the case when multiple cracks are initiated and grown around the inner circumference of a pipe. The PFM software, pc-PRAISE, used for the evaluation of ESC sizes had fracture mechanics models based on available data and models in the early 2000s. The stress intensity factor solutions used in pc-PRAISE were generated for a pipe radius-to-thickness ratio, Ri/t, of 5, and used a root-mean-square (RMS) averaged methodology. And the crack growth model was based on NUREG/CR-2189, Volume 5. This paper presents the results of evaluations to calculate a limited number of ESC sizes using updated fracture mechanics models for stress intensity factor and fatigue crack growth rates. The effect of crack growth due to stress corrosion cracking (SCC) in determining the ESCs is also discussed. The impact of the revised ESCs by performing two sample fatigue flaw tolerance problems and the associated results are also presented and discussed in this paper.

Analysis of Stress Intensity Factor and Crack Propagation for Alloy X-750 Pressure Vessel with a Blunting Crack

2010 ◽  
Vol 303-304 ◽  
pp. 63-83
Author(s):  
Ehsan Mahdavi ◽  
Mahmoud Mosavi Mashhadi ◽  
M. Amidpour
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Propagation ◽  
Crack Growth ◽  
Pressure Vessel ◽  
Element Analysis ◽  
Linear Elastic ◽  
The Stability

It is well known that the crack growth rate fatigue and stress corrosion cracking can be approximated by a power function of the stress intensity factor. In this study, stress intensity factor for elliptical crack under the uniform tension in linear elastic fracture mechanics (LEFM) is investigated therefore for this purpose, a pressure vessel modeled by finite element. A crack modeled on the pressure vessel and then the stress intensity factor for crack propagation in different methods is evaluated. Finite element analysis calculates stress intensity factor in the values of the J-integral are based on the stress intensity factors, JK, and by evaluating the contour integral directly, JA. The stability of crack growth is considered so the ductile crack extension is determined by pursuing the equilibrium between loading and crack resistance. Using especial method of meshing caused to have accurate results. This method causes to decrease run time and considerable accuracy. Then stress intensity factor is calculated for different position of the crack such as crack front and then compared to each other.

Multiple Fatigue Crack Growth Prediction Using Stress Intensity Factor Solutions Modified by Empirical Interaction Factors

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Shinji Konosu ◽  
Kyosuke Kasahara
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
The Body ◽  
Multiple Cracks ◽  
Growth Prediction ◽  
Interaction Factors

It is generally believed that multiple fatigue crack growth prediction is difficult with the use of conventional stress intensity factor (SIF) solution calculations because of issues such as SIF magnification and shielding effects. Therefore, almost all the existing Fitness for Service (FFS) rules such as the ASME Code Section XI and JSME Code adopt the procedure whereby multiple cracks grow independently after applying a certain alignment rule based on the initial crack configuration and are combined immediately into an enveloping crack when the crack tips touch. In some cases, the results of the procedures in the existing FFS rules are less accurate in predictions of the service life of cracked components. Therefore, there is still room for improvement, although the procedures are simple for utilities. This paper describes a new approach to predict fatigue crack growth life of multiple nonaligned cracks by the use of SIF solutions modified by empirical interaction factors. Several examples of two nonaligned cracks illustrate the accuracy and effectiveness of the procedure by comparison with numerical analysis by the body force method for two-dimensional problems and with the experimental results given in the literature for three-dimensional problems.

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.

Multiple Fatigue Crack Growth Prediction Using Standard Stress Intensity Factor Solutions

2010 ◽  
Author(s):  
Shinji Konosu ◽  
Kyosuke Kasahara
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
The Body ◽  
Multiple Cracks ◽  
Growth Prediction ◽  
Dimensional Models

It is generally believed that multiple fatigue crack growth prediction is difficult with the use of standard stress intensity factor (SIF) solution calculations because of the complicated nature of such issues as magnification and shielding effects. Therefore, almost all the existing FFS rules such as the ASME Section XI Code and JSME Code adopt the procedure whereby multiple cracks grow independently after applying a certain alignment rule based on the initial crack configuration and are combined immediately into an enveloping crack when the crack tips touch. In some cases, the results of the procedures in the existing FFS rules can be unrealistic and may lead to unreliable predictions of the service life of cracked components. This paper describes a new approach to predicting multiple nonaligned fatigue crack growth life by the use of standard SIF solutions. Several examples, as compared with numerical analysis by the body force method for two-dimensional models and experimental results in the literature for three-dimensional models, illustrate the accuracy and effectiveness of the procedure.

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