scholarly journals Influence Coefficients to Calculate Stress Intensity Factors for an Elliptical Crack in a Plate

2002 ◽  
Author(s):  
Patrick Le Delliou ◽  
Bruno Barthelet
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Atomic Energy Commission ◽  
Finite Thickness ◽  
Elliptical Crack ◽  
Intensity Factors ◽  
Normal Loading ◽  
Influence Coefficients ◽  
Wide Range

Crack assessment in engineering structures relies first on accurate evaluation of the stress intensity factors. In recent years, a large work has been conducted in France by the Atomic Energy Commission to develop influence coefficients for surface cracks in pipes. However, the problem of embedded cracks in plates (and pipes) which is also of practical importance has not received so much attention. Presently, solutions for elliptical cracks are available either in infinite solid with a polynomial distribution of normal loading or in plate, but restricted to constant or linearly varying tension. This paper presents the work conducted at EDF R&D to obtain influence coefficients for plates containing an elliptical crack with a wide range of the parameters: relative size (2a/t ratio), shape (a/c ratio) and crack eccentricity (2e/t ratio where e is the distance from the center of the ellipse to the plate mid plane). These coefficients were developed through extensive 3D finite element calculations: 200 geometrical configurations were modeled, each containing from 18000 to 26000 nodes. The limiting case of the tunnel crack (a/c = 0) was also analyzed with 2D finite element calculation (50 geometrical configurations). The accuracy of the results was checked by comparison with analytical solutions for infinite solids and, when possible, with solutions for finite-thickness plates (generally loaded in constant tension). These solutions will be introduced in the RSE-M Code that provides rules and requirements for in-service inspection of French PWR components.

Influence Coefficients of Stress Intensity Factors for Curved Tubing With a Semi-Elliptical Crack

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Kirsten Plante ◽  
Choon-Lai Tan
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Crack Depth ◽  
Elliptical Crack ◽  
Radius Ratio ◽  
Intensity Factors ◽  
Cross Sectional ◽  
Influence Coefficients ◽  
Wide Range ◽  
Angular Extent

The boundary element method is employed to determine polynomial influence coefficients of stress intensity factors, KI, for a semi-elliptical crack in internally pressurized thick-walled curved tubing. Numerical results of these coefficients are obtained for a wide range of geometric parameters; they are the bend radius ratio, cross-sectional radius ratio, angular extent of the bend, and relative crack depth. The use of influence coefficients allows KI solutions to be determined for different load cases without repetitive 3D stress analysis of the cracked body. This is demonstrated for the case of autofrettage where the effects on KI of the residual stresses arising from it are presented.

STRESS INTENSITY FACTORS OF A SEMI-ELLIPTICAL CRACK IN A HOLLOW CYLINDER

2015 ◽  
Vol 39 (3) ◽  
pp. 557-568
Author(s):  
Shiuh-Chuan Her ◽  
Hao-Hi Chang
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Hollow Cylinder ◽  
Stress Intensity Factors ◽  
Surface Crack ◽  
Crack Depth ◽  
Weight Functions ◽  
Intensity Factors ◽  
Regular Elements ◽  
Wide Range

In this investigation, the weight function method was employed to calculate stress intensity factors for semi-elliptical surface crack in a hollow cylinder. A uniform stress and a linear stress distribution were used as the two references to determine the weight functions. These two factors were obtained by a three-dimensional finite element method which employed singular elements along the crack front and regular elements elsewhere. The weight functions were then applied to a wide range of semi-elliptical surface crack subjected to non-linear loadings. The results were validated against finite element data and compared with other analyses. In the parametric study, the effects of the ratio of the surface crack depth to length ranged from 0.2 to 1.0 and the ratio of the crack depth to the wall thickness ranged from 0.2 to 0.8 on stress intensity factors were investigated.

scholarly journals Stress-Intensity Factors for Internal Surface Cracks in Cylindrical Pressure Vessels

1980 ◽  
Vol 102 (4) ◽  
pp. 342-346 ◽  
Author(s):  
J. C. Newman ◽  
I. S. Raju
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Intensity ◽  
Wall Thickness ◽  
Stress Intensity Factors ◽  
Crack Depth ◽  
Internal Surface ◽  
Surface Cracks ◽  
Intensity Factors ◽  
Wide Range

The purpose of this paper is to present stress-intensity factors for a wide range of semi-elliptical surface cracks on the inside of pressurized cylinders. The ratio of crack depth to crack length ranged from 0.2 to 1; the ratio of crack depth to wall thickness ranged from 0.2 to 0.8; and the ratio of wall thickness to vessel radius was 0.1 to 0.25. The stress-intensity factors were calculated by a three-dimensional finite-element method. The finite-element models employ singularity elements along the crack front and linear-strain elements elsewhere. The models had about 6500 degrees of freedom. The stress-intensity factors were evaluated from a nodal-force method. An equation for the stress-intensity factors was obtained from the results of the present analysis. The equation applies over a wide range of configuration parameters and was within about 5 percent of the present results. A comparison was also made between the present results and other analyses of internal surface cracks in cylinders. The results from a boundary-integral equation method were in good agreement (± 2 percent) and those from another finite-element method were in fair agreement (± 8 percent) with the present results.

Stress intensity factors for semi-elliptical surface cracks in semicircularly notched tension plates

1997 ◽  
Vol 32 (3) ◽  
pp. 229-236 ◽  
Author(s):  
X B Lin ◽  
R A Smith
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Crack Depth ◽  
Finite Thickness ◽  
J Integral ◽  
Surface Cracks ◽  
Intensity Factors ◽  
Wide Range ◽  
Half Length ◽  
Half Thickness

Stress intensity factors for semi-elliptical surface cracks located at the centre of a semicircular edge notch in a finite thickness plate subjected to a remote tensile load are presented in a tabulated format. A wide range of geometry ratios are considered. They are all combinations of the following ratios: the ratio of crack surface half-length to plate half-thickness, c/t = 0.2, 0.4, 0.6, 0.8 and 0.95; the ratio of crack depth to surface half-length, a/c = 0.2, 0.4, 0.6, 0.8 and 1; and the ratio of notch radius to plate half-thickness, r/t = 0.5, 1, 2 and 3. Both the quarter-point displacement and J.-integral methods based on three-dimensional finite element analyses were employed for the calculation of stress intensity factors. The calculation accuracy was studied by analysing the J.-integral path independence and comparing stress intensity factor results with other solutions available in the literature.

Stress intensity factors for radial cracks in annular and solid discs under constant angular velocity

2005 ◽  
Vol 40 (2) ◽  
pp. 217-223 ◽  
Author(s):  
A. R Gowhari-Anaraki ◽  
S J Hardy ◽  
R Adibi-Asl
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Angular Velocity ◽  
Stress Intensity Factors ◽  
Constant Angular Velocity ◽  
Experimental Sample ◽  
Intensity Factors ◽  
Rotating Disc ◽  
Crack Configuration ◽  
Wide Range

The finite element method has been used to predict the stress intensity factors for single- and double-edge cracks in six annular and solid rotating discs under constant angular velocity. Linear elastic fracture mechanics finite element analyses have been performed and the results are presented in the form of crack configuration factors for a wide range of component and crack geometry parameters. These parameters are chosen to be representative of typical practical situations and have been determined from evidence presented in the open literature. The extensive range of crack configuration factors obtained from the analyses are then used to obtain equivalent prediction equations using a statistical multiple non-linear regression model. The accuracy of this model is measured using a multiple coefficient of determination, R2, where 0 ≤ R2 ≤ 1. This coefficient is found to be greater than or equal to 0.98 for all cases considered in this study, demonstrating the quality of the model fit to the data. Predictive equations for stress intensity factors enable designers to predict the fatigue life of these components easily. It is also suggested that one of the component configurations (i.e. the cracked slit rotating disc) can be selected as a suitable experimental sample to measure the real fracture toughness of rotating components, using the relevant predictive equation presented in this study. Finally a fracture criterion is also suggested graphically to determine the limit load value of angular velocity for similar rotating disc components.

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