Prediction of Fatigue Crack Propagation of Sub-Surface Cracks by “SCAN”

2004 ◽  
Author(s):  
Masaki Shiratori ◽  
Naoki Yoshikawa ◽  
Fuminori Iwamatsu ◽  
Hisao Matsushita ◽  
Shigeo Omata ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Surface Crack ◽  
Influence Function ◽  
Surface Cracks ◽  
Finite Element Analyses ◽  
Influence Function Method ◽  
Influence Coefficients ◽  
Asme Code

The authors have proposed an influence function method by which stress intensity factor, K, of surface cracks can be calculated easily for arbitrarily distributed surface stresses. They have developed the database of influence coefficients, Kij, for various types of surface cracks through a series of finite element analyses [1]. And they also have developed a software system “SCAN”, based upon the above developed database, by which K-values of surface cracks can be evaluated promptly, and further, fatigue crack propagation can be simulated easily by a personal computer. In this paper the authors have studied how they can apply the SCAN system to the problem of the sub-surface cracks. They have developed “SCAN Sub-Surface Crack Version”, where SCAN is improved by newly analyzed influence coefficients for a series of sub-surface cracks, and by following the scenario described in ASME CODE, SECTION XI [2]. They have found that the database of a surface crack in a flat plate already installed in the SCAN system, with the above described Kij database for sub-surface cracks, can be applied to this problem with satisfactory accuracy, which means the K-values of this problem can be evaluated promptly by the SCAN system, and the propagation of small sub-surface cracks can be simulated easily.

Estimation of Fatigue Crack Propagation of Subsurface Cracks by “SCAN”

2006 ◽  
Author(s):  
Shin Nakanishi ◽  
Fuminori Iwamatsu ◽  
Masaki Shiratori ◽  
Hisao Matsushita
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Surface Crack ◽  
Surface Cracks ◽  
Subsurface Crack ◽  
Subsurface Cracks ◽  
Influence Coefficients ◽  
Asme Code

The authors have proposed an influence function method to calculate stress intensity factor, K, of the surface cracks. This method makes the calculating task easier for arbitrarily distributed surface stresses. They have developed the database of influence coefficients, Kij, for various types of surface cracks through a series of finite element analyses.[1] They also have developed a software system “SCAN” (Surface Crack Analysis), from the database. The K values of surface cracks can be evaluated immediately, and further, fatigue crack propagation can be simulated easily with a personal computer. A fatigue crack often initiates from a defect located at the subsurface of a structural member. In this case, it is important to account for the fatigue life from the initiation of a subsurface crack to its propagation into a surface crack. However, since it is difficult to simulate this process precisely, the authors have proposed a simple model about the transition from a subsurface crack into a surface crack based upon ASME CODE SECTION XI [2] and WES 2805 STANDARD. [3] They have developed a SCAN system – Subsurface Crack Version-. They calculated the fatigue life for some models of subsurface cracks and compared the quantitative differences between two standards.

Fatigue Crack Propagation Analysis of Nozzle Corner Using the Influence Function Method

2002 ◽  
Author(s):  
Mayumi Ochi ◽  
Kiminobu Hojo ◽  
Takeharu Nagasaki
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Influence Function ◽  
Function Method ◽  
Fatigue Cracks ◽  
Crack Depth ◽  
Element Analysis ◽  
Influence Function Method ◽  
Calculation System

A calculation system has been developed in order to evaluate the thermal fatigue crack propagation of a semi-elliptical crack on the corner of a nozzle. One fatigue crack was assumed on the inner surface of the nozzle corner of a representative PWR reactor vessel. The stress intensity factors K were calculated at the deepest and outermost surface points of the crack using the influence function method. A database was prepared for the cracks with a depth of 0.022 t − 0.5 t (t: pressure vessel thickness) and an aspect ratio of 0.1a/c – 1.0 a/c (a: crack depth and c: half surface width). Eight-noded solid elements and the finite element analysis code MARC were used. The calculation system enables the propagation of fatigue cracks at nozzle corners to be carried out in a very short time.

Application of Surface Crack Analysis System ‘SCAN’ to Cracks at Hole

2002 ◽  
Author(s):  
Nagatoshi Seki ◽  
Masaki Shiratori ◽  
Toshiro Miyoshi ◽  
Youichi Yamashita ◽  
Kenji Sakano
Keyword(s):  
Surface Crack ◽  
Notch Root ◽  
Fem Analysis ◽  
Radius Of Curvature ◽  
Surface Cracks ◽  
Finite Element Analyses ◽  
Influence Function Method ◽  
Influence Coefficients ◽  
Enormous Amount ◽  
Analysis System

The authors have proposed an influence function method by which stress intensity factor, K, of surface cracks can be calculated easily for arbitrarily distributed surface stresses. They have developed the database of influence coefficients, Kij, for various types of surface cracks through a series of finite element analyses. And they also have developed a software system “SCAN”, based upon the above developed database, by which K-values of surface cracks can be evaluated promptly, and further, fatigue crack propagation can be simulated easily by a personal computer. In this paper the authors have studied how they can apply the SCAN system to the problem of the surface cracks initiated from the edge of a circular hole of a rectangular plate. Since circular notches have various radiuses of curvature, the concentrated stress distribution at the notch root is different depending upon the radius of curvature. Therefore, strictly speaking, K-values have to be evaluated for each case, one by one, which means enormous amount of FEM analysis are necessary. But the authors have found that the database of a surface crack in a flat plate already installed in the SCAN system can be applied to this problem with satisfactory accuracy, which means the K-values of this problem can be evaluated promptly by the SCAN system.

Load path effect on fatigue crack propagation in I+II+III mixed mode conditions – Part 2: Finite element analyses

2014 ◽  
Vol 62 ◽  
pp. 113-118 ◽  
Author(s):  
Flavien Fremy ◽  
Sylvie Pommier ◽  
Erwan Galenne ◽  
Stephan Courtin ◽  
Jean-Christophe Le Roux
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Mixed Mode ◽  
Finite Element Analyses ◽  
Load Path

Development of Surface Crack Analysis Program and its Application to Some Practical Problems

2011 ◽  
Author(s):  
Masaki Shiratori ◽  
Masaki Nagai ◽  
Naoki Miura
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Surface Crack ◽  
Surface Stress ◽  
Structural Components ◽  
Paris Law

The authors have developed a software system called “SCANP™” by which users can analyze residual lives of surface-cracked structural components such as pressure vessels and their piping systems due to fatigue or SCC. The basic concept is based upon an influence function method by which the stress intensity factor “K” of a surface crack can be calculated for arbitrarily distributed surface stresses on the cracked surface. The authors and his group have developed a great number of database of “Kij”, the influence coefficient of the stress intensity factor, for many different types of surface-cracked structural components. The database is installed into the SCANP and the K-values for one of these cracks against an arbitrarily distributed surface stress can be calculated easily through the algorithm of superposition of the surface stress and the corresponding Kij data. The fatigue crack propagation can be simulated by integrating the Paris’ law, and it is easy to estimate the residual fatigue lives up to the leakage. Further, residual lives due to SCC, stress corrosion cracking, can be simulated by following the algorithm described in the JSME Standard. In this paper it is demonstrated how the SCANP works by applying it to some practical industrial problems such as fatigue crack and SCC crack propagations into welded residual stress field, and fatigue crack propagation initiated from double-surface cracks. In the latter case the simulation was compared with the experimental results in order to evaluate the validity of the developed system. It was found that the scatter of the material data describing the Paris’ law is far larger than the errors in estimating K-values, and therefore, the choice of these material data is very important when a user wants to use this program effectively. In order to use the developed program correctly, the authors have organized “SCANP User Meeting” where only the members can use the program. In the User Meeting the users give presentations about how they applied SCANP to analyze practical problems, and discuss about the validity of the modeling, and the computed results. In this paper some of these activities will be described, and the problem of verification, validation and uncertainty quantification is discussed.

Competition Between Fatigue Crack Propagation and Wear

1993 ◽  
Vol 115 (1) ◽  
pp. 141-147 ◽  
Author(s):  
H. Fan ◽  
L. M. Keer ◽  
W. Cheng ◽  
H. S. Cheng
Keyword(s):  
Fatigue Crack ◽  
Flow Stress ◽  
Cyclic Loading ◽  
Crack Propagation ◽  
Crack Length ◽  
Fatigue Crack Propagation ◽  
Surface Crack ◽  
Yield Limit ◽  
Semi Empirical

Based on a semi-empirical derivation of the Paris fatigue law, the fatigue crack length a is related to the yield limit or flow stress, which ultimately is related to the hardness of the material. The analysis considers together the cyclic loading, which tends to increase the surface crack length, and the wear, which tends to decrease the crack length at the surface, and shows that under certain conditions a stable crack length may be developed. Experiments conducted on two test groups ((i) Rc = 58.5 and (ii) Rc = 62.7) tend to support the present analysis.

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