Stress Intensity Factors for an Embedded Crack Near a Cylindrical Cavity

1988 ◽  
pp. 1-8
Author(s):  
H. Abé ◽  
K. Hayashi ◽  
S. Takahashi
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Cylindrical Cavity ◽  
Intensity Factors ◽  
Embedded Crack

Consideration of Reduction in Stiffness due to Cracking and the Impact on Standard Stress Intensity Factor Solutions

2017 ◽  
Author(s):  
Daniel M. Blanks
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Nozzle Geometry ◽  
Intensity Factors ◽  
Factor Solution ◽  
Small Component ◽  
Embedded Crack ◽  
The Impact

An API 579-1/ASME FFS-1 Failure Assessment Diagram based Fitness-for-Service assessment was carried out on an embedded crack-like flaw found in a nozzle to shell weld in a pressure vessel. Stress intensity factors were initially calculated by utilizing stress results from a Finite Element Analysis (FEA) of an uncracked configuration, with the standard embedded crack stress intensity factor solution given in API 579-1/ASME FFS-1. Due to the complex nozzle geometry and flaw size, a second analysis was carried out, incorporating a crack into the FEA model, to calculate the stress intensity factors and evaluate if the standard solution could be applied to this geometry. A large difference in the resulting stress intensity factors was observed, with those calculated by the FEA with the crack incorporated into the model to be twice as high as those calculated by the standard solutions, indicating the standard embedded crack stress intensity factor solution may be non-conservative in this case. An investigation was carried out involving a number of studies to determine the cause of the difference. Beginning with an elliptical shaped embedded crack in a plate, the stress intensity factor calculated with an idealized 3D crack mesh agreed with the API 579-1/ASME FFS-1 solution. Examining other crack locations, and crack shapes, such as a constant depth embedded crack, revealed how the solution began to differ. The greatest difference was found when considering a crack mesh with a small component height (i.e. the distance measured perpendicular from the crack face to the top of the mesh). A close agreement was then found between the stress intensity factors calculated in the nozzle model and an idealized crack mesh with component heights representative of the true geometry. This revealed that reduced structural stiffness is a key factor in the calculation of the stress intensity factors for this geometry, due to the close proximity of the embedded crack to the inner surface of the nozzle. It was found that this reduction is potentially significant even with relatively small crack sizes. This paper details the investigation, and aims to provide the reader with an awareness of situations when the standard stress intensity factor solutions may no longer be valid, and offers general recommendations to consider when calculating stress intensity factors in these situations.

Mixed-Mode Stress Intensity Factors for an Embedded Crack in an Orthotropic FGM Coating

2008 ◽  
Author(s):  
S. Dag ◽  
K. A. Ilhan ◽  
F. Erdogan ◽  
Glaucio H. Paulino ◽  
Marek-Jerzy Pindera ◽  
...  
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Mixed Mode ◽  
Intensity Factors ◽  
Mode Stress ◽  
Embedded Crack

Calculation of the Stress Intensity Factors for Elliptical Cracks Embedded in a Weld under Tensile Loading I：Single Crack

2011 ◽  
Vol 217-218 ◽  
pp. 1419-1424 ◽  
Author(s):  
Xiao Yu Liu ◽  
Cai Fu Qian ◽  
Hui Fang Li ◽  
Hui Zheng
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Maximum Stress ◽  
Numerical Solutions ◽  
Pressure Vessels ◽  
Intensity Factors ◽  
Maximum Stress Intensity ◽  
Embedded Crack ◽  
Elliptical Cracks ◽  
Maximum Stress Intensity Factor

In this paper, an embedded elliptical crack in a weld of pressure vessels under tension was taken into consideration, and stress intensity factors at the crack tip were calculated numerically with the emphasis on the influences of the weld surface. It is found that when the embedded depth is 4 times larger than the minor semi-axis of the ellipse, the weld surface effects on the crack can be neglected and the numerical solutions for the stress intensity factors well agree with the analytical ones. This result can be used to distinguish a shallow embedded crack from a deep embedded crack. It is also found that the point with maximum stress intensity factor is always located at the end of minor axis of the ellipse no mater the shape of the ellipse is and how deep it was embedded.

Calculation of the Stress Intensity Factors for Elliptical Cracks Embedded in a Weld under Tensile Loading II：Double Cracks

2011 ◽  
Vol 217-218 ◽  
pp. 1425-1429
Author(s):  
Xiao Yu Liu ◽  
Cai Fu Qian ◽  
Hui Fang Li ◽  
Hui Zheng
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Major Axis ◽  
Pressure Vessels ◽  
Intensity Factors ◽  
Major Semi Axis ◽  
Crack Interactions ◽  
Maximum Stress Intensity ◽  
Embedded Crack ◽  
Elliptical Cracks

In this paper, double embedded elliptical cracks in a weld of pressure vessels under tension was taken into consideration, and stress intensity factors at the crack tip were calculated with the emphasis on the interaction between cracks. It is found that when the distance between the double embedded elliptical cracks is larger than the major semi-axis of the ellipse, influence between the cracks can be neglected. Unlike the single embedded crack, owing to the crack interactions, the point with maximum stress intensity factor is not always at the end of the minor axis of the ellipse, it may swift to the end of major axis, especially when the ellipse is close to a circle.

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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