Estimation of Elastic Crack Opening Displacement for Thin Elbows With Circumferential Through-Wall Cracks

2015 ◽  
Author(s):  
Min-Kyu Kim ◽  
Han-Bum Surh ◽  
Min-Gu Won ◽  
Nam-Su Huh ◽  
Moon-Ki Kim ◽  
...  
Keyword(s):  
Crack Opening Displacement ◽  
Nuclear Power ◽  
Crack Opening ◽  
Three Dimensional ◽  
Opening Displacement ◽  
Dimensional Finite Element ◽  
Elastic Crack ◽  
Thin Walled ◽  
Three Dimensional Finite Element ◽  
Leak Before Break

Leak-before-break (LBB) is an important concept that could confirm design and integrity evaluation of nuclear power plant piping. For the LBB analysis, the detective leakage rate should be calculated for a through-wall cracked pipes. For this calculation, the crack opening displacement (COD) calculation is essential. Recently, sodium faster reactor (SFR) which has thin-walled pipes with Rm/t ranged 30–40 was introduced and then the investigation of these thin walled pipes and elbows has received great attention in the LBB evaluation. In this context, the three-dimensional finite element (FE) analyses for thin elbows with circumferential crack under in-plane bending are carried out to investigate the elastic COD values. Finally, the solution for elastic COD which can cover sufficiently thin elbow is successfully addressed.

Estimates of Elastic Crack Opening Displacements of Slanted Through-Wall Cracks in Plate and Cylinder

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Nam-Su Huh ◽  
Do-Jun Shim ◽  
Yeon-Sik Yoo ◽  
Suhn Choi ◽  
Keun-Bae Park
Keyword(s):  
Finite Element ◽  
Crack Opening ◽  
Three Dimensional ◽  
Bending Moment ◽  
Element Model ◽  
Finite Element Analyses ◽  
Opening Displacement ◽  
Elastic Crack ◽  
Leak Before Break ◽  
The Finite Element Model

This paper provides tractable solutions for elastic crack opening displacement (COD) of slanted through-wall cracks in plates and cylinders. The solutions were developed via detailed three dimensional elastic finite element analyses. The COD values were calculated along the thickness at the center of the crack. As for the loading conditions, only remote tension was considered for the plates, whereas remote tension, global bending moment, and internal pressure were considered for the cylinders. The finite element model employed in the present analysis was verified by using existing solutions for a cylinder with an idealized circumferential through-wall crack. The present results can be used to evaluate leak rates of slanted through-wall cracks, which can be used as a part of a detailed leak-before-break analysis considering more realistic crack shape development.

Three Dimensional Finite Element Analyses of Welding Residual Stresses of a Repaired Weld

2018 ◽  
Author(s):  
Mingya Chen ◽  
Weiwei Yu ◽  
Fei Xue ◽  
Francis Ku ◽  
Zhilin Chen ◽  
...  
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Nuclear Power ◽  
Power Plants ◽  
Three Dimensional ◽  
Fe Model ◽  
Dimensional Finite Element ◽  
Surge Line ◽  
Line Slope ◽  
Three Dimensional Finite Element

The objective of this study is to correct installation non-conformance of a surge line using the excavation and re-weld method which is widely used in nuclear power plants. The surge line with a backslope was not at the required design level after initial installation. In order to solve the problem, a repairing technology is shown as follows: the weld was successively excavated and welded again while the surge line slope was corrected with the help of jacks. Because many of the degradation mechanisms relevant to power plant components can be accelerated by the presence of welding residual stresses (WRS), the WRS caused by the repairing process need to be studied. In this paper, the WRS simulation technique employed in this project is sophisticated. It utilizes a 3-D finite element (FE) model, and simulates the weld sequencing and excavation. Moreover, the WRS simulation performed in this project not only uses the un-axisymmetric model, but also considers the deformation caused by the external jacking loads. The results show that the repairing process is effective, and strain damage induced by the welding repair is also acceptable.

scholarly journals Engineering Leak-Before-Break Analyses of Pressurized Piping: Part I- Crack Opening Displacement

2004 ◽  
Vol 47 (4) ◽  
pp. 591-599 ◽  
Author(s):  
Yun-Jae KIM ◽  
Nam-Su HUH ◽  
Young-Jin KIM ◽  
Jun-Seok YANG
Keyword(s):  
Crack Opening Displacement ◽  
Crack Opening ◽  
Opening Displacement ◽  
Leak Before Break

Static and vibration characteristics of thin-walled box beams: An experimental investigation

2017 ◽  
Vol 20 (10) ◽  
pp. 1540-1559 ◽  
Author(s):  
Kiana Kashefi ◽  
Abdul Hamid Sheikh ◽  
Michael C Griffith ◽  
MS Mohamed Ali ◽  
Kazuo Tateishi
Keyword(s):  
Three Dimensional ◽  
Time History ◽  
Displacement Transducer ◽  
Vibration Characteristics ◽  
Element Analysis ◽  
Linear Variable Displacement Transducer ◽  
Dimensional Finite Element ◽  
Box Beams ◽  
Thin Walled ◽  
Three Dimensional Finite Element

Static and vibration characteristics of thin-walled straight and curved box beams were investigated experimentally. Three different beam configurations were considered for the tests: one straight and two curved box beams. The load was applied at the centroid of the box section for the straight and one curved beam specimens. However, for the other curved specimen, the load was applied eccentrically to investigate its behavior under the additional torsion induced by the eccentricity. Displacements and strains were obtained using linear variable displacement transducer, one-directional and rosette strain gages. The specimens were excited using an impact at their free ends. The time history of strains was obtained to calculate natural frequencies and damping ratios. The experiment results were compared with those obtained from three-dimensional finite element analysis for all cases. The results obtained from implementing tests on the straight specimen were also used to validate an efficient numerical method recently developed by the authors.

Analysis of 45 Steel Rectangular Thin-Walled Parts Milling Deformation

2015 ◽  
Vol 667 ◽  
pp. 22-28 ◽  
Author(s):  
Jing Li ◽  
Zhan Li Wang ◽  
Ping Xi ◽  
Yang Jiao
Keyword(s):  
Prediction Model ◽  
Three Dimensional ◽  
Material Model ◽  
Machining Accuracy ◽  
Machining Deformation ◽  
Dimensional Finite Element ◽  
Prediction And Control ◽  
Length Direction ◽  
Thin Walled ◽  
Three Dimensional Finite Element

Aiming at the problem that the machining accuracy of 45 steel rectangular thin-walled parts are difficult to ensure because of poor rigidity, poor manufacturability and easy machining deformation, it used the three-dimensional finite element method, determined the material model of 45 steel and established a prediction model of 45 steel rectangular thin-walled parts milling deformation. The prediction results display that the deformation of the workpiece shows obvious parabola in length direction and a linear decreasing trend in width direction. It verifies the correctness of the prediction model through milling experiments and provides the method and basis for the prediction and control of machining deformation of 45 steel thin-walled parts.

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