Analytical Solution of Stress Intensity Factor for Clamped SENT Specimens

2016 ◽  
Author(s):  
Xian-Kui Zhu
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Oil And Gas ◽  
Full Range ◽  
Test Procedure ◽  
Direct Determination ◽  
Oil And Gas Industry ◽  
Wide Range ◽  
Low Constraint

Single edge-notched tension (SENT) specimen in clamped end conditions was identified as a low-constraint fracture test specimen, and is preferred for use in the oil and gas industry in direct determination of fracture toughness or resistance curves for low-constraint conditions. Over the years, different SENT test methods have been developed, including DNV-RP-F108 (2006) test practice, CanMet (2008) J-integral resistance curve test procedure, ExxonMobil (2010) CTOD test procedure, and others. On this basis, a SENT test standard BS 8571 was developed and published in December of 2014. However, the stress intensity factor K used in BS 8571 was expressed in a very complicated function. Recently, the present author found that this K solution is incorrect for deep cracks of a/W>0.6, and corrected the K solution in the original format of polynomial functions. To verify the corrected result, this paper obtained a wide-range, simpler analytical K solution for clamped SENT specimens using the crack compliance method. Results show that the proposed K solution and its curve-fit are more accurate over the full range of crack sizes, and agree well with available finite element results.

A Wide Range Stress Intensity Factor Solution for Single Edge Notched Tension Specimen With Clamped Ends

2016 ◽  
Author(s):  
Xian-Kui Zhu
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Oil And Gas ◽  
Test Procedure ◽  
Oil And Gas Industry ◽  
Test Methods ◽  
Single Edge ◽  
Wide Range ◽  
Low Constraint

Single edge notched tension (SENT) specimen with clamped ends has been accepted in the oil and gas industry as a low-constraint fracture test specimen to directly determine fracture toughness or resistances in low constraint conditions. Different SENT test methods have been developed, including DNV-RP-F108 test practice, CANMET J-resistance curve test procedure, ExxonMobil CTOD test procedure, and others. Based on these methods, a SENT test standard BS 8571 was developed and published in December of 2014. However, the stress intensity factor K used in BS 8571 was a very complicated function and difficult to use. Moreover, the present author found that this complicated K solution is correct only for a/W≤0.6, but incorrect for deep cracks of a/W>0.6. In order to obtain a simple and accurate K solution for the clamped SENT specimen, this paper revisits this topic. Using the crack compliance method, the desired K solution is obtained. Results show that the proposed K solution and its curve fit are very accurate over a wide range of crack sizes, and validated by existing finite element results of K for the SENT specimens.

A Surrogate Model for Predicting Stress Intensity Factor: An Application to Oil and Gas Industry

2017 ◽  
Author(s):  
Arvind Keprate ◽  
R. M. Chandima Ratnayake ◽  
Shankar Sankararaman
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Oil And Gas ◽  
Gaussian Process Regression ◽  
Complex Loading ◽  
Oil And Gas Industry ◽  
Crack Size ◽  
Data Points ◽  
Time Required

Evaluation of the stress intensity factor (SIF) for a crack propagating in a structural component is the analytical basis of linear elastic fracture mechanics (LEFM) approach. Handbook solutions give accurate SIF results for simple crack geometries. For intricate crack geometries and complex loading conditions finite element method (FEM), is used to predict SIF. The main drawback of FEM techniques is that they are prohibitively expensive in terms of computing cost and also very time consuming. In this manuscript, authors have presented a Gaussian Process Regression Model (GPRM), which may be used as an alternative to FEM for predicting SIF of a propagating crack. The GPRM is firstly trained using 70 SIF values obtained by FEM, and then validated by comparing the values of SIF predicted by GPRM and FEM for 30 data points (i.e. combination of crack size and loading). On comparing the aforementioned values the average residual percentage between the two is 2.57%, indicating good agreement between GPRM and FEM model. Also, the time required to predict SIF of 30 data points is reduced from 30 mins (for FEM) to 10 seconds with the help of proposed GPRM.

Edge Crack in Longitudinal Butt-Welded Joint in Thick-Wall Cylinder

2021 ◽  
Vol 2 (2) ◽  
pp. 66-80
Author(s):  
Yunan Prawoto ◽  
Rachmad Imbang Trittjahjono
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Stress Distribution ◽  
Intensity Factor ◽  
Oil And Gas ◽  
Welded Joint ◽  
Oil And Gas Industry ◽  
Thick Wall ◽  
Cylindrical Shape ◽  
Element Analysis

Thick-wall vessels and pipes cylindrical shape are very typical in power plant, chemical, processing, oil and gas industry. The equipment with cylindrical shape can be either thin or thick wall which depends on the function of that particular equipment. Typically, thick-wall cylinder is used when the equipment is needed to accommodate high pressure contents. Mostly, cracks appear either on the internal or external of a thick-wall cylinder. Primarily, when welding is applied in the fabrication of the thick-wall cylinder, cracks can easily appear due to solidification or hydrogen embrittlement at the welded joint, typically butt-welded joint. Hence, it is critical to examine the stress distribution along the crack and resolve the stress intensity factor of the cracks in both welded and non-welded internally pressurized thick-wall cylinder. Finite element analysis has been conducted using the engineering software, ABAQUS CAE to investigate the stress distribution and to perform the evaluation of stress intensity factor. Besides, weight function method has also been used by other researchers to determine the factor of stress intensity for both welded and non-welded thick-wall cylinder. The results were compared in terms of both of the methods applied. The last, the effect of the butt-welded joint profile in thick-wall cylinder has also been investigated.

A Review of K-Solutions for Through-Thickness Flaws in Cylinders and Spheres

2007 ◽  
Author(s):  
Ali Mirzaee Sisan ◽  
Isabel Hadley ◽  
Sarah E. Smith ◽  
Mike Smith
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Loading Conditions ◽  
Wide Range ◽  
Cylinders And Spheres

This paper reviews different stress intensity factor solutions for a wide range of configurations and loading conditions for a cylinder with axial and circumferential through thickness cracks and a sphere with through thickness meridional (equatorial) cracks. The most appropriate solutions to use are identified.

Comparison of the Stress Intensity Factor Influence Coefficients for Axial ID Surface Cracks in Cylinders of RSE-M and API 579-1

2015 ◽  
Author(s):  
Patrick Le Delliou ◽  
Stéphane Chapuliot
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Nuclear Power ◽  
Crack Depth ◽  
Wall Stress ◽  
Surface Point ◽  
Evaluation Procedures ◽  
Influence Coefficients ◽  
Wide Range

Analytical evaluation procedures for determining the acceptability of flaw detected during in-service inspection of nuclear power plant components are provided in Appendix 5.4 of the French RSE-M Code. Linear elastic fracture mechanics based evaluation procedures require calculation of the stress intensity factor (SIF). In Appendix 5.4 of the RSE-M Code, influence coefficients needed to compute the SIF are provided for a wide range of surface axial or circumferential flaws in cylinders, the through-wall stress field being represented by a cubic equation. On the other hand, Appendix C of API 579-1 FFS procedure provides also a very complete set of influence coefficients. The paper presents the comparison of the influence coefficients from both documents, focused on axial ID semi-elliptical surface flaws in cylinders. The cylinder and crack geometries are represented by three ratios: Ri/t, a/t, and a/c, where Ri, t, a, and c are respectively the inner radius, the wall thickness, the crack depth and one-half of the crack length. The solutions for the coefficients G0 and G1 at the deepest point and at the surface point are investigated. At the deepest point, the agreement between the solutions is good, the relative difference being lower than 2 %, except for the plate (Ri/t = ∞) at a/c = 0.125 and 0.0625 and a/t = 0.8 (around 5 %). At the surface point, the agreement between both solutions is not so good. At this point, the relative differences depend strongly on the a/c ratio, being larger for elongated cracks (with low a/c ratios). However, it must be recalled that the absolute values of the coefficients are low at the surface point for elongated cracks, and that for these cracks the critical point regarding the stress intensity factor is the deepest point.

A Wide Range Stress Intensity Factor Expression for the C-Shaped Specimen

1980 ◽  
Vol 8 (6) ◽  
pp. 314 ◽  
Author(s):  
KC Lieb ◽  
R Horstman ◽  
KA Peters ◽  
RL Meltzer ◽  
MB Vieth ◽  
...  
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Wide Range ◽  
Factor Expression

Accounting for Natural Crack Growth Shapes During Environmental Cracking

2012 ◽  
Author(s):  
Do-Jun Shim ◽  
Fredrick Brust ◽  
Gery Wilkowski
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Growth ◽  
Growth Analysis ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Gas Production ◽  
Oil And Gas Production ◽  
Growth Method

Environmental cracking, such as stress-corrosion cracking (SCC), is a significant issue for a variety of industries, such as those dealing with power generation — nuclear, oil and gas production, and pipeline transmission, etc. SCC is particularly of concern in that catastrophic failures can occur even at low applied stress levels (e.g., residual stress produced by welding). Thus, it is critical to evaluate the behavior of SCC for structural integrity assessments. In this paper, three different crack growth methods (i.e., idealized crack growth analysis, crack growth analysis using finite element alternating method; FEAM, and the natural crack growth method) are summarized. These methods all utilize the stress intensity factor for crack growth evaluations. Thus, these methods can be used for assessment of environmental cracking that is based on stress intensity factor. Various examples are shown in this paper to demonstrate the applicability of these methods. Comparisons of results obtained from different methods are also provided in this paper.

scholarly journals The Application of Fracture Mechanics to the Problem of Crevasse Penetration

1976 ◽  
Vol 17 (76) ◽  
pp. 223-228 ◽  
Author(s):  
R. A. Smith
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Close Agreement ◽  
Elastic Stress ◽  
Intensity Factors ◽  
Wide Range ◽  
Sharp Crack

AbstractThe elastic stress intensity factor is a parameter used in fracture mechanics to describe stress conditions in the vicinity of the tip of a sharp crack. By superimposing solutions of stress intensity factors for different loading conditions, equations are derived which model crevasses in ice. Solutions are presented for the theoretical depth of isolated crevasses, free from or partially filled with water. Close agreement exists with a previous calculation by Weertman using a different technique. The effect of crevasse spacing is investigated and it is demonstrated that closer spacing always reduces crevasse depth, but over a wide range of spacing the predicted variation in depth is slight.

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