Fracture Assessment Procedures for Steel Pipelines Using a Modified Reference Stress Solution

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Tomasz Tkaczyk ◽  
Noel P. O’Dowd ◽  
Kamran Nikbin
Keyword(s):  
Three Dimensional ◽  
Assessment Procedure ◽  
Element Analysis ◽  
Welded Steel ◽  
Defect Assessment ◽  
Reference Stress ◽  
Stress Solution ◽  
Dimensional Finite Element ◽  
Estimation Scheme ◽  
Three Dimensional Finite Element

An accurate defect assessment procedure is needed to ensure integrity of girth welded steel pipelines while avoiding unnecessary repairs. An integral part of such a procedure is an estimation scheme for the crack driving force. In this work, a modified reference stress solution was developed for the assessment of elastic-plastic pipes with surface breaking defects. For the particular case of interest (reeled offshore pipelines), the loading is phrased in terms of applied strain. The stress-based approach has therefore been extended to the case of strain/displacement control. The results obtained using the modified reference stress solution have been compared with a three-dimensional finite-element analysis. Very good agreement has been obtained. The predictions are also significantly better than those obtained from existing approaches. A comparison between the proposed method and full scale testing will be presented in a separate paper.

Fracture Assessment Procedures for Steel Pipelines Using a Modified Reference Stress Solution

2008 ◽  
Author(s):  
Tomasz Tkaczyk ◽  
Noel P. O’Dowd ◽  
Kamran Nikbin
Keyword(s):  
Three Dimensional ◽  
Assessment Procedure ◽  
Element Analysis ◽  
Welded Steel ◽  
Defect Assessment ◽  
Reference Stress ◽  
Stress Solution ◽  
Dimensional Finite Element ◽  
Estimation Scheme ◽  
Three Dimensional Finite Element

An accurate defect assessment procedure is needed to ensure integrity of girth welded steel pipelines while avoiding unnecessary repairs. An integral part of such a procedure is an estimation scheme for the crack driving force. In this work, a modified reference stress solution was developed for the assessment of elastic-plastic pipes with surface breaking defects. For the particular case of interest (reeled offshore pipelines) the loading is phrased in terms of applied strain. The stress-based approach has therefore been extended to the case of strain/displacement control. The results obtained using the modified reference stress solution have been compared with a three-dimensional finite-element analysis. Very good agreement has been obtained. The predictions are also significantly better than those obtained from existing approaches. A comparison between the proposed method and full scale testing will be presented in a separate paper.

J-R Curves From Circumferentially Through-Wall-Cracked Pipe Tests Subjected to Combined Bending and Tension—Part II: Experimental and Analytical Validation

1998 ◽  
Vol 120 (4) ◽  
pp. 412-417 ◽  
Author(s):  
N. Miura ◽  
G. M. Wilkowski
Keyword(s):  
Internal Pressure ◽  
Three Dimensional ◽  
Combined Loading ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Estimation Scheme ◽  
Materials Used ◽  
Three Dimensional Finite Element ◽  
Η Factor ◽  
J Estimation

In Part I (Miura and Wilkowski, 1998) of this paper, the theory of the two η-factor solutions for circumferentially through-wall-cracked pipes subjected to combined bending and tension due to internal pressure was presented. These solutions seemed to give reasonable predictions by comparing with the existing simplified J-estimation scheme. It was also ascertained that the J would be underestimated if the effect of the internal pressure was not properly considered. Consequently, this paper presents the application of these solutions to full-scale pipe tests. The tests were performed at 288°C (550°F) under combined bending and internal pressure. The materials used for the tests were both carbon steel and stainless steel. The effect of combined loading on the J-R curves was determined and compared to C(T) specimen J-R curves. The solutions were then verified by using three-dimensional finite element analysis.

Finite Element Analysis of Nonuniformity of Tires with Imperfections5

2007 ◽  
Vol 35 (3) ◽  
pp. 226-238 ◽  
Author(s):  
K. M. Jeong ◽  
K. W. Kim ◽  
H. G. Beom ◽  
J. U. Park
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Radial Force ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Force Variation ◽  
Three Dimensional Finite Element

Abstract The effects of variations in stiffness and geometry on the nonuniformity of tires are investigated by using the finite element analysis. In order to evaluate tire uniformity, a three-dimensional finite element model of the tire with imperfections is developed. This paper considers how imperfections, such as variations in stiffness or geometry and run-out, contribute to detrimental effects on tire nonuniformity. It is found that the radial force variation of a tire with imperfections depends strongly on the geometrical variations of the tire.

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