scholarly journals Influence of Pressure and Thermal Parameters on Stresses Analysis of Pressurized and Cracked Pipes

2019 ◽  
Vol 35 (6) ◽  
pp. 1640-1646
Author(s):  
Abdullah K. Okab ◽  
Khalid A. Mohammed ◽  
Abdurahman A. Gatta
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Length ◽  
J Integral ◽  
Stress Distributions ◽  
Intensity Factors ◽  
Modeling Process ◽  
Oil Gas ◽  
Pressurized Cylinder

Due to the dangerous alarm for many engineering applications such as energy generating systems and pipelines transporting oil, gas and its derivatives under high-pressure, a study of the effect of thermal and mechanical loading on the cracked materials and pipes at high-temperature environments is required. In this work, the influence of the thermal loadings on stresses analysis of pressurized and cracked pressurized pipes has been solved numerically where the mode I crack's type has been considered. The modeling process mainly aims to find the stress intensity factor, J-integral calculations and the stress distributions. The accuracy of the results has been compared with analytical solutions of a pressurized cylinder. The mesh around the crack have been modeled in a careful way to obtain accurate stress distributions. It was found that the surface’s temperature has a significant effect on stress distributions, for example, the stresses increased by 50% with increasing the temperature differences between the inner and outer pipe’s diameter. Additionally, the stress intensity factor and the J-integrals values were calculated for different crack length ratios and temperature differences. It is found at the crack length ratio of 0.6 the stress intensity factors increased up to 50% from 45 to 76 and J-integral increased by 77% from 250 kN/m to 430 kN/m. Also, the influence of fluid’s temperature investigated, and the result showed that by increasing the fluid’s temperature without cracks, the stresses decreased by 33%. Also, it was found that for different crack length ratios the J-integral and stress intensity reduces when the fluid’s temperature increases.

Formulation for Stress Intensity Factors and J-Integral Calculation by Eddy Current Testing

2015 ◽  
Vol 660 ◽  
pp. 225-230 ◽  
Author(s):  
Salaheddine Harzallah ◽  
Mohamed Chabaat ◽  
Sekoura Benissad
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Eddy Current ◽  
Eddy Currents ◽  
J Integral ◽  
Intensity Factors ◽  
Magnetic Vector ◽  
Current Testing ◽  
Set Up

In this paper, we present a method for computing the Stress Intensity Factor (SIF) and J-Integral, by measuring and testing related Eddy currents. In the process, we provide a magnetic vector based formulations for the theoretical set up. Furthermore, we provide relevant applications having theory consistent results.

Stress Intensity Factor for Cracks at the Toe of Welded Joints

2007 ◽  
Vol 348-349 ◽  
pp. 257-260
Author(s):  
Paolo Livieri ◽  
Roberto Tovo
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Welded Joints ◽  
Crack Extension ◽  
J Integral ◽  
Intensity Factors ◽  
Toe Angle ◽  
The Stability

This paper proposes a method for evaluation of the Stress Intensity Factors (SIFs) of embedded cracks lying along the bisector of the welded toe angle. The SIFs are calculated on the basis of the JV parameter (extension of the J-integral to a sharp V-notch) for a path radius equal to the crack extension without modelling the crack. The numerical calculations in the paper show the stability of the proposed method also with course meshes.

Stress Analysis of Rectangular Plate With Bilateral Interface Cracks Under Hybrid Boundary Conditions

2005 ◽  
Author(s):  
Jiemin Liu ◽  
Guangtao Ma ◽  
Toshiyuki Sawa
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Length ◽  
Rectangular Plate ◽  
Stress Distributions ◽  
Interface Cracks ◽  
Fixed Boundary ◽  
Crack Tips ◽  
External Loads

Presented is an approach for obtaining whole-field stress distributions of a bi-material rectangular plate, which is composed of plate I and plate II with a fixed boundary and subjected to external loads, using elasticity mechanics theory. There are two cracks at the edges of the interface of plate I and plate II, which are called as bilateral interface cracks. In the analysis, the effects of the ratio of Young’s modulus of material I (plate I) and to that of material II (plate II) and the ratio of the crack length to the width of the plate on the stress distributions in the vicinity of the interface were examined. Stress Intensity Factor (SIF) and normalized SIF equations were also calculated through the stresses in the vicinity of the crack tips.

Investigation of Temperature Effect on Cracked Pressurized Pipes

2018 ◽  
Author(s):  
Karim Egab ◽  
Saad K. Oudah ◽  
Ameen A. Nassar ◽  
Hassan R. Hassan ◽  
Yeasin Bhuiyan
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Stress Distribution ◽  
Intensity Factor ◽  
Surface Temperature ◽  
Crack Length ◽  
Thermal Loading ◽  
Thermal Conditions ◽  
J Integral ◽  
Manufacturing Defects

Pipes carrying heated-pressurized fluid have numerous manufacturing defects that resulted from thermal loadings. Therefore, study the thermal loading effect on the cracked pipes is important to decrease the risks of pipe fracture during their operation. In this work, the effect of the thermal stress distribution on the cracked pipes has been studied numerically. The “mode I” type of crack has been considered for the study. The results have been validated with an available analytical solution for a pristine cylinder. The temperature and stress distribution for different crack length ratio has been studied. The influence of surface’s temperature and fluid’s temperature on radial stress, tangential stresses are discussed. The J-integral and stress intensity factor in analyzed for various thermal conditions. In addition, the radial and tangential stress variations of the various pressurized fluids which have various temperature have been investigated. The stress intensity factor and the J-integrals were calculated for different crack length ratios. In addition, the effect of surface temperature has been studied. It was found that the surface and fluid’s temperature affects the stress distributions and J-integral values. The results show that the J-integral and the stress intensity factor increases as the surface temperature of the pipe increases while their values decrease with increase the surface temperature.

Representation and Partitioning of Welding Residual Stress Distributions for Use in Structural Integrity Assessments

2007 ◽  
Author(s):  
Adam Toft ◽  
David Beardsmore ◽  
Peter James ◽  
John Sharples ◽  
Michael Martin
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Structural Integrity ◽  
Stress Distributions ◽  
Intensity Factors ◽  
Polynomial Representations ◽  
Stress Profiles

In order to obtain good estimates of stress intensity factors in a structural integrity assessment, the accuracy with which a residual stress distribution is represented should be commensurate with the importance of localised peaks in residual stress, in particular where such peaks lie within the region under assessment. This paper describes work undertaken to investigate the importance of accurately representing residual stress distributions in structural integrity assessments. This has been carried out by comparing regular polynomial representations of residual stress distributions, combined with available weight function stress intensity factor solutions (as provided in the R6 procedures) with alternative polynomial representations of residual stress distributions, which provide a more accurate fit in the region of the crack. Such improvements in representation of residual stress profiles provide an indication as to how stress intensity factor solutions could, in future, be modified in order to result in improved accuracy of calculated stress intensity factors. Representation by partitioning residual stress profiles into membrane, bending and self-balancing components, in terms of providing a more straight-forward route for curve-fitting of residual stress profiles is considered. The investigation considers several transverse, through-thickness residual stress distributions. Stress intensity factors are calculated for a variety of crack sizes. Representation of the residual stress profiles in the stress intensity factor solutions are compared, as are the results of the stress intensity factor calculations. The conclusions arising provide guidance as to how current methods of curve fitting a residual stress distribution may be improved in cases where current methods may not be accurate. Advice is also provided as to the relative merits of representing residual stress distributions as a set of partitioned components or as a single distribution.

Stress-Intensity Factors for Internal and External Surface Cracks in Cylindrical Vessels

1982 ◽  
Vol 104 (4) ◽  
pp. 293-298 ◽  
Author(s):  
I. S. Raju ◽  
J. C. Newman
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Internal Pressure ◽  
Stress Intensity Factors ◽  
Crack Depth ◽  
Surface Cracks ◽  
Stress Distributions ◽  
Intensity Factors

The purpose of this paper is to present stress-intensity factor influence coefficients for a wide range of semi-elliptical surface cracks on the inside or outside of a cylinder. The crack surfaces were subjected to four stress distributions: uniform, linear, quadratic, and cubic. These four solutions can be superimposed to obtain stress-intensity factor solutions for other stress distributions, such as those caused by internal pressure and by thermal shock. The results for internal pressure are given herein. The ratio of crack depth to crack length 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 or 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. The present results were also compared to other analyses of surface cracks in cylinders. The results from a boundary-integral equation method agreed well (±2 percent), and those from other finite-element methods agreed fairly well (±10 percent) with the present results.

Effect of specimen crack lengths on stress intensity factor for Al6061-TiC composites using experimental and 3D numerical methods

2017 ◽  
Vol 8 (5) ◽  
pp. 506-515 ◽  
Author(s):  
Raviraj M.S. ◽  
Sharanaprabhu C.M. ◽  
Mohankumar G.C.
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Length ◽  
Finite Element Simulations ◽  
Experimental Results ◽  
Crack Mouth Opening Displacement ◽  
3D Finite Element ◽  
Content Type

Purpose The purpose of this paper is to present the determination of critical stress intensity factor (KC) both by experimental method and three-dimensional (3D) finite element simulations. Design/methodology/approach CT specimens of different compositions of Al6061-TiC composites (3wt%, 5wt% and 7wt% TiC) with variable crack length to width (a/W=0.3-0.6) ratios are machined from as-cast composite block. After fatigue pre-cracking the specimens to a required crack length, experimental load vs crack mouth opening displacement data are plotted to calculate the KC value. Elastic 3D finite element simulations have been conducted for CT specimens of various compositions and a/W ratios to compute KC. The experimental results indicate that the magnitude of KC depends on a/W ratios, and significantly decreases with increase in a/W ratios of the specimen. Findings From 3D finite element simulation, the KC results at the centre of CT specimens for various Al6061-TiC composites and a/W ratios show satisfactory agreement with experimental results compared to the surface. Originality/value The research work contained in this manuscript was conducted during 2015-2016. It is original work except where due reference is made. The authors confirm that the research in their work is original, and that all the data given in the article are real and authentic. If necessary, the paper can be recalled, and errors corrected.

Weight Functions for an External Longitudinal Semi-Elliptical Surface Crack in a Thick-Walled Cylinder

1997 ◽  
Vol 119 (1) ◽  
pp. 74-82 ◽  
Author(s):  
A. Kiciak ◽  
G. Glinka ◽  
D. J. Burns
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Surface Crack ◽  
Complex Stress ◽  
Weight Functions ◽  
Stress Distributions ◽  
Intensity Factors ◽  
Reference Stress ◽  
Pressurized Cylinder ◽  
Walled Cylinder

Mode I weight functions were derived for the deepest and surface points of an external radial-longitudinal semi-elliptical surface crack in a thick-walled cylinder with the ratio of the internal radius to wall thickness, Ri/t = 1.0. Coefficients of a general weight function were found using the method of two reference stress intensity factors for two independent stress distributions, and from properties of weight functions. Stress intensity factors calculated using the weight functions were compared to the finite element data for several different stress distributions and to the boundary element method results for the Lame´ hoop stress in an internally pressurized cylinder. A comparison to the ASME Pressure Vessel Code method for deriving stress intensity factors was also made. The derived weight functions enable simple calculations of stress intensity factors for complex stress distributions.

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