Composite coating effect on stress intensity factors of aluminum pressure vessels with inner circumferential crack by X-FEM

2021 ◽  
pp. 104445
Author(s):  
Majid Tasavori ◽  
Arash Tavakoli Maleki ◽  
Isa Ahmadi
Keyword(s):  
Stress Intensity ◽  
Composite Coating ◽  
Stress Intensity Factors ◽  
Pressure Vessels ◽  
Intensity Factors ◽  
Circumferential Crack

Analysis of Surface Flaw in Pressure Vessels by a New 3-Dimensional Alternating Method

1982 ◽  
Vol 104 (4) ◽  
pp. 299-307 ◽  
Author(s):  
T. Nishioka ◽  
S. N. Atluri
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Surface Crack ◽  
Crack Surface ◽  
Pressure Vessels ◽  
Pressure Loading ◽  
Intensity Factors ◽  
Alternating Method ◽  
Magnification Factors

An alternating method, in conjunction with the finite element method and a newly developed analytical solution for an elliptical crack in an infinite solid, is used to determine stress intensity factors for semi-elliptical surface flaws in cylindrical pressure vessels. The present finite element alternating method leads to a very inexpensive procedure for routine evaluation of accurate stress intensity factors for flawed pressure vessels. The problems considered in the present paper are: (i) an outer semi-elliptical surface crack in a thick cylinder, and (ii) inner semi-elliptical surface cracks in a thin cylinder which were recommended for analysis by the ASME Boiler and Pressure Vessel Code (Section III, App. G, 1977). For each crack geometry of an inner surface crack, seven independent loadings, such as internal pressure loading on the cylinder surface and polynomial pressure loadings from constant to fifth order on the crack surface, are considered. From the analyses of these loadings, the magnification factors for the internal pressure loading and the polynomial influence functions for the polynomial crack surface loadings are determined. By the method of superposition, the magnification factors for internally pressurized cylinders are rederived by using the polynomial influence functions to check the internal consistency of the present analysis. These values agree excellently with the magnification factors obtained directly. The present results are also compared with the results available in literature.

Analysis of Interaction Behavior of Surface Flaws in Pressure Vessels

1986 ◽  
Vol 108 (1) ◽  
pp. 24-32 ◽  
Author(s):  
P. E. O’Donoghue ◽  
T. Nishioka ◽  
S. N. Atluri
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Pressure Vessels ◽  
Influence Functions ◽  
Surface Cracks ◽  
Intensity Factors ◽  
Alternating Method ◽  
Circumferential Crack ◽  
Magnification Factors ◽  
Surface Flaws

The evaluation of stress intensity factors for surface flaw problems and, in particular, semi-elliptical surface cracks in cylindrical pressure vessels has been well developed using the finite element alternating method. Some of the examples presented here include the interaction effects due to multiple internal longitudinal surface cracks in cylinders as recommended for analysis in the ASME Boiler and Pressure Vessel Code (Section XI). For each crack geometry, several loading cases are considered including internal pressure and polynomial pressure loadings from constant to fourth order. By the method of superposition, the magnification factors for internally pressurized cylinders are rederived using the polynomial influence functions. These influence functions give useful information for design purposes such as in the analysis of a thermally shocked cylinder. The problem of a single circumferential crack in a cylinder is also investigated using the finite element alternating method, and a number of results for such problems are also presented here.

3-D Stress Intensity Factors for Arrays of Inner Radial Lunular or Crescentic Cracks in Thin and Thick-Walled Spherical Pressure Vessels

2008 ◽  
Author(s):  
M. Perl ◽  
V. Bernstein
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Crack Depth ◽  
Pressure Vessels ◽  
Life Assessment ◽  
Intensity Factors ◽  
Fe Method ◽  
Inner Radius ◽  
Wide Range ◽  
Spherical Pressure

Some spherical pressure vessels are manufactured by methods such as the Integrated Hydro-Bulge Forming (IHBF) method, where the sphere is composed of a series of double curved petals welded along their meridional lines. Such vessels are susceptible to multiple radial cracking along the welds. For fatigue life assessment and fracture endurance of such vessels one needs to evaluate the Stress Intensity Factors (SIF) distribution along the fronts of these cracks. However, to date, only one 3-D solution for the SIF for a circumferential crack in a thick sphere is available, as well as 2-D SIFs for one through the thickness crack in thin spherical shells. In the present paper, mode I SIF distributions for a wide range of lunular and crescentic cracks are evaluated. The 3-D analysis is performed, via the FE method employing singular elements along the crack front, for five geometries representing thin, moderately thick, and thick spherical pressure vessels with outer to inner radius ratios of η = Ro/Ri = 1.01, 1.05, 1.1, 1.7, and 2.0. SIFs are evaluated for arrays containing n = 1–20 cracks; for a wide range of crack depth to wall thickness ratio, a/t, from 0.025 to 0.95; and for various ellipticities of the crack, i.e., the ratio of crack depth to semi crack length, a/c, from 0.2 to 1.5. The obtained results clearly indicate that the SIFs are considerably affected by the three-dimensionality of the problem and by the following parameters: the geometry of the sphere-η, the number of cracks in the array-n, the depth of the cracks-a/t, and their ellipticity-a/c.

scholarly journals Calculation of Outer Crack Stress Intensity Factors for Nozzle Junctions in Cylindrical Pressure Vessels Using FCPAS

2021 ◽  
Author(s):  
Murat Bozkurt ◽  
David Nash ◽  
Asraf Uzzaman
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Pressure Vessel ◽  
Pressure Vessels ◽  
Stress System ◽  
Parameter Study ◽  
Intensity Factors

Abstract Pressure vessels can be subjected to various external local forces and moments acting in combination with main internal pressure. As a result of the stress system set up, and in the presence of attachment welds, surface cracks can occur on the interior and exterior walls. If these cracks cannot be detected at an early stage, there is a real potential for the vessel to rupture with obvious dangerous consequences. The behavior of fractured or geometric discontinuity structures can be investigated with linear elastic fracture mechanics (LEFM) parameters. The stress intensity factor (SIF) is the leading one, and with correct calculations, it can produce the stress intensity in the crack tip region. In cylinder-cylinder intersections subject to local loads, the maximum stress distribution occurs in and around these opening areas and failure in the system usually occurs in this region. Using this approach, the present study develops three-dimensional mixed mode stress intensity factor solutions on for external cracks on nozzle joints in cylindrical pressure vessels nozzle junctions for a variety of geometrical configurations. This was undertaken using a finite element approach and employing a bespoke software tool and solver, FCPAS - Fracture and Crack Propagation Analysis System — to create the finite element mesh and propagation characteristics. From this, a parameter study examining the influence of the crack shape, size and position was carried out with a fixed pressure vessel nozzle cylinder intersection geometry configuration and the appropriate stress intensity factors identified and reported. The FCPAS tool is shown to be an effective approach to modelling and characterizing cracks in pressure vessel nozzles.

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