Application of weight function technique for stress intensity factor and failure assessment diagram with a realistic stress profile

KSME Journal ◽  
1996 ◽  
Vol 10 (1) ◽  
pp. 105-113
Author(s):  
Kwang -Il Ho
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Weight Function ◽  
Function Technique ◽  
Stress Profile ◽  
Failure Assessment Diagram ◽  
Failure Assessment

scholarly journals Admissibility of External Cracks in a Pipeline API X60 Using the SINTAP Procedure

2017 ◽  
Vol 61 (4) ◽  
pp. 261
Author(s):  
Kaddour Bahram ◽  
Benattou Bouchouicha ◽  
Mohamed Benguediab ◽  
Abdelkader Slimane
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Modeling And Simulation ◽  
Safety Factors ◽  
Diagram Method ◽  
Failure Assessment Diagram ◽  
Failure Assessment ◽  
Abaqus Software

In this paper we tried to apply the failure assessment diagram method on an API X60 pipeline under two pressures 70 and 90 bar, this work will be divided into two parts; the first part will be devoted to modeling and simulation of a pipeline under pressure 70/90 bar. With abaqus software to determine the stress intensity factor of several ratios, The second part will focus on the exploitation of these results in order to draw the diagram of evaluation of the failure (FAD), once finished, We can pronounce on the vulnerability of the cracks which can cause the ruin of the pipeline to study, on mode of ruin and proposed safety factors.

Stress Intensity Factor Calculation Using a Weight Function Method

2007 ◽  
Author(s):  
Rui Sun ◽  
Zongwen An ◽  
Hong-Zhong Huang ◽  
Qiming Ma
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Propagation ◽  
Weight Function ◽  
Function Method ◽  
Method Comparison ◽  
Finite Size ◽  
Unstable Crack ◽  
Weight Function Method

Propagation of a critical unstable crack under the action of static or varying stresses is determined by the intensity of strain field at tips of the crack. Stress intensity factor (SIF) is an important parameter in fracture mechanics, which is used as a criterion to judge the unstable propagation of a crack and plays an important role in calculating crack propagation life. SIF is related to both geometrical form and loading condition of a structure. In the paper, a weight function method is introduced to study crack propagation of center through cracks and edge cracks in a finite-size plate. In addition, finite element method, linear regression, and polynomial interpolating technique are used to simulate and verify the proposed method. Comparison studies among the proposed and current methods are performed as well. The results show that the weight function method can be used to calculate SIF easily.

Universal Weight Function Consistent Method to Fit Polynomial Stress Distribution for Calculation of Stress Intensity Factor

2010 ◽  
Author(s):  
Douglas A. Scarth ◽  
Steven X. Xu
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Stress Distribution ◽  
Intensity Factor ◽  
Weight Function ◽  
Wall Thickness ◽  
Function Method ◽  
Polynomial Equation ◽  
Evaluation Procedure ◽  
Weight Function Method

Procedures for analytical evaluation of flaws in nuclear pressure boundary components are provided in Section XI of the ASME B&PV Code. The flaw evaluation procedure requires calculation of the stress intensity factor. Engineering procedures to calculate the stress intensity factor are typically based on a polynomial equation to represent the stress distribution through the wall thickness, where the polynomial equation is fitted using the least squares method to discrete data point of stress through the wall thickness. However, the resultant polynomial equation is not always an optimum fit to stress distributions with large gradients or discontinuities. Application of the weight function method enables a more accurate representation of the stress distribution for the calculation of the stress intensity factor. Since engineering procedures and engineering software for flaw evaluation are typically based on the polynomial equation to represent the stress distribution, it would be desirable to incorporate the advantages of the weight function method while still retaining the framework of the polynomial equation to represent the stress distribution when calculating the stress intensity factor. A method to calculate the stress intensity factor using a polynomial equation to represent the stress distribution through the wall thickness, but which provides the same value of the stress intensity factor as is obtained using the Universal Weight Function Method, is provided in this paper.

Comparison Between API 579-1/ASME FFS-1 and ASME VIII Division 3 Stress Intensity Factor Solutions Used for Fracture Mechanics and Fatigue Analysis of Thick Walled Cylinders

2008 ◽  
Author(s):  
Jan G. M. Keltjens
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Life Time ◽  
Time Study ◽  
Worked Example ◽  
Failure Assessment ◽  
Section Viii ◽  
Burst Analysis

The paper discusses the differences between API 579-1/ASME FFS-1-1/ASME FFS-1 [1] and ASME Section VIII Division 3 [2] stress intensity factor solutions. In addition to this, the use of the Failure Assessment Diagram (FAD) in leak before burst analysis is compared to the present Division 3 approach. The paper contains the background of both approaches and a worked example demonstrating the effect of both methods. Finally, a simplified fatigue crack growth based life time study is presented.

Closed-Form Calculation of Stress Intensity Factor for an Axial ID Surface Flaw in Cylinder Subjected to Weld Residual Stresses

2013 ◽  
Author(s):  
Douglas A. Scarth ◽  
Steven X. Xu
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Weight Function ◽  
Closed Form ◽  
Function Method ◽  
Current Method ◽  
Surface Flaw ◽  
Weight Function Method ◽  
Influence Coefficients

A method for calculating the stress intensity factor for linear elastic fracture mechanics based flaw evaluation is provided in Appendix A-3000 of ASME Section XI. In the 2010 Edition of ASME Section XI, the calculation of stress intensity factor for a surface crack is based on characterization of stress field with a cubic equation and use of influence coefficients. The influence coefficients are currently only provided for flat plate geometry in tabular format. The ASME Section XI Working Group on Flaw Evaluation is in the process of rewriting Appendix A-3000. Proposed major updates include the implementation of explicit use of Universal Weight Function Method for calculation of the stress intensity factor for a surface flaw and the inclusion of closed-form influence coefficients for cylinder geometry. The explicit use of weight function method eliminates the need for fitting polynomial equations to the actual through-thickness stress distributions at crack location. In this paper, the proposed Appendix A procedure is applied to calculate the stress intensity factors in closed-form for an axial ID surface flaw in a cylinder subjected to a set of nonlinear hoop weld residual stress profiles. The calculated stress intensity factor results are compared with the results calculated based on the current method in Appendix A using cubic equations to represent the stress distribution. Three-dimensional finite element analyses were performed to verify the accuracy of the stress intensity factor results calculated based on the current and proposed Appendix A procedures. The results in this paper support the implementation of the proposed stress intensity factor calculation procedure into ASME Code.

Displacement Controlled Stress Intensity Factor Solutions for Structural Integrity Assessments of Welding Residual Stress Distributions

2008 ◽  
Author(s):  
Adam Toft ◽  
David Beardsmore ◽  
Colin Madew ◽  
Huego Teng ◽  
Mark Jackson
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Residual Stresses ◽  
Weight Function ◽  
Driving Force ◽  
Welding Residual Stress ◽  
Crack Plane ◽  
Crack Driving Force

Within the UK nuclear industry the assessment of fracture in pressurised components is often carried out using procedures to calculate the margin of safety between a lower-bound fracture toughness and the crack driving force. Determination of the crack driving force usually requires the calculation of elastic stress intensity factor solutions for primary loads and secondary loads arising from weld residual stresses and/or thermal stresses. Within established UK assessment procedures weight function solutions are available which allow the stress intensity factors to be calculated from the through-wall opening-mode stress distribution in an uncracked component. These weight-function solutions are generally based on models where either no boundary condition is applied, or where one is applied at a distance either side of the crack plane that is very long compared with the crack size and wall thickness. Such solutions do not take into account any reduction in the stress field that might occur as the distance from the crack faces increases. Weld residual stress fields may often be expected to reduce in this manner. A separate, earlier study has shown that the stress intensity factor for a cracked plate loaded in displacement control decreases substantially as the loading plane is moved closer to the crack plane. It would therefore be expected that a similar reduction in stress intensity factor would be obtained for a residual stress analysis when displacement boundary conditions are imposed at a distance relatively close to the crack plane. This paper describes an investigation of the differences, particularly in terms of a reduction in calculated stress intensity factor, which may arise from application of displacement controlled stress intensity factor solutions, as compared with load controlled solutions, when considering weld residual stresses. Consideration is also given as to how new displacement controlled stress intensity factor solutions could be developed by modification of existing load controlled solutions.

Sign in / Sign up

Export Citation Format

Share Document