Collapse Characteristics of a Thin-Walled Elbow: Validation of an Analytical Procedure

1987 ◽  
Vol 109 (4) ◽  
pp. 394-401 ◽  
Author(s):  
A. K. Dhalla
Keyword(s):  
Analytical Procedure ◽  
Large Diameter ◽  
Local Deformation ◽  
Load Test ◽  
Test Facility ◽  
Deformation Response ◽  
Collapse Characteristics ◽  
Shell Analysis ◽  
Measured Deformation ◽  
Thin Walled

A nonlinear analysis procedure is validated in this paper to predict deformation response, up to collapse, of thin-walled Liquid Metal Reactor (LMR) piping elbows. Nonlinear shell analysis predictions are compared with experimental measurements of two full-scale large diameter (406 mm), thin-walled (D/t = 38), piping elbows tested at room temperature and at an elevated temperature in the Multi-Load Test Facility (MLTF) at Westinghouse. The overall and local deformation predictions agree very well with the measured deformation responses up to 60 percent of the measured plastic collapse moment, Mpce. The analytical-experimental correlation is reasonable up to 0.8 Mpce. At higher load levels the correlation is not as good; at collapse the analysis overpredicts measured deformations by as much as 30 percent.

Flow-Induced Vibration of a Large-Diameter Elbow Piping Based on Random Force Measurement Caused by Conveying Fluid: Visualization Test Results

2005 ◽  
Author(s):  
Tomomichi Nakamura ◽  
Tadashi Shiraishi ◽  
Yoshihide Ishitani ◽  
Hisato Watakabe ◽  
Hiromi Sago ◽  
...  
Keyword(s):  
Force Measurement ◽  
Large Diameter ◽  
Pressure Fluctuations ◽  
Pressure Sensors ◽  
Maximum Flow ◽  
Axial Direction ◽  
Random Force ◽  
Test Facility ◽  
Flow Induced Vibration ◽  
Correlation Lengths

A 1/3 scale flow-induced vibration test facility that simulates the hot-leg piping of the JNC sodium-cooled fast reactor (JSFR) is used to investigate the pressure fluctuations of the pipe, where the high velocity fluid flows inside the piping. By the measurement of the pressure drop in the elbow piping while changing the Reynolds number, the similarity law of this model is confirmed. To evaluate the flow-induced vibrations for the hot-leg and cold-leg pipes, the random force distributions along the pipe and their correlations are measured with pressure sensors in a water loop. It is found that a flow velocity-dependent periodic phenomenon in the rear region of the elbow, and the maximum flow-induced random vibration force in the pipe are observed in the region of flow separation downstream the elbow. Finally, a design method is proposed with power spectral densities of the pressure fluctuations classified into four sections, correlation lengths in the axial direction divided into three sections, and with correlation lengths in the tangential direction into four sections.

scholarly journals Evaluation of stresses in large diameter, thin walled piping at support locations

1992 ◽  
Author(s):  
B.J. Bryan ◽  
H.E. Jr. Flanders ◽  
G.B. Jr. Rawls
Keyword(s):  
Large Diameter ◽  
Thin Walled

scholarly journals Free oscillations of thin-walled bimetallic pipelines of large diameter on an elastic foundation

2018 ◽  
Vol 193 ◽  
pp. 02027
Author(s):  
Vladimir Sokolov ◽  
Igor Razov ◽  
Evgeniy Koynov
Keyword(s):  
Elastic Foundation ◽  
Nuclear Power ◽  
Large Diameter ◽  
Compressive Force ◽  
Free Oscillations ◽  
Working Pressure ◽  
Momentum Theory ◽  
Internal Working ◽  
Nonlinear Version ◽  
Thin Walled

In the article, solutions are obtained for a thin-walled bimetallic pipeline. Solutions are obtained, and the frequencies of free oscillations are investigated taking into account the internal working pressure, the longitudinal compressive force, and the elastic foundation. The solutions were obtained on the basis of a geometrically nonlinear version of the semi-momentum theory of cylindrical shells of the middle bend. The proposed calculations can find application in the nuclear power industry, aviation, and the petrochemical industry.

scholarly journals Dynamic Impedances of Offshore Rock-Socketed Monopiles

2019 ◽  
Vol 7 (5) ◽  
pp. 134 ◽  
Author(s):  
Rui He ◽  
Ji Ji ◽  
Jisheng Zhang ◽  
Wei Peng ◽  
Zufeng Sun ◽  
...  
Keyword(s):  
Numerical Model ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Dynamic Stiffness ◽  
Large Diameter ◽  
Offshore Wind ◽  
Offshore Wind Turbines ◽  
Thin Walled ◽  
Rock Parameters ◽  
Radiative Damping

With the development of offshore wind energy in China, more and more offshore wind turbines are being constructed in rock-based sea areas. However, the large diameter and thin-walled steel rock-socketed monopiles are very scarce at present, and both the construction and design are very difficult. For the design, the dynamic safety during the whole lifetime of the wind turbine is difficult to guarantee. Dynamic safety of a turbine is mostly controlled by the dynamic impedances of the rock-socketed monopile, which are still not well understood. How to choose the appropriate impedances of the socketed monopiles so that the wind turbines will neither resonant nor be too conservative is the main problem. Based on a numerical model in this study, the accurate impedances are obtained for different frequencies of excitation, different soil and rock parameters, and different rock-socketed lengths. The dynamic stiffness of monopile increases, while the radiative damping decreases as rock-socketed depth increases. When the weathering degree of rock increases, the dynamic stiffness of the monopile decreases, while the radiative damping increases.

scholarly journals Spring Deformation Gauge for Measuring Local Deformations in Triaxial Apparatus

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Mostafa A. Ismail ◽  
Yasser E. Ibrahim
Keyword(s):  
Accurate Determination ◽  
Cost Effective ◽  
Local Deformation ◽  
Spring Steel ◽  
Metal Strip ◽  
Triaxial Tests ◽  
Strain Gauges ◽  
Soil Stiffness ◽  
Triaxial Apparatus ◽  
Measured Deformation

Local measurement of deformations of a soil specimen has become inevitable for accurate determination of soil stiffness in triaxial tests. Although there are now many devices that can be used to perform this task, each has its own advantages and limitations that render development of new devices with better desirable features. This paper presents an innovative device called spring deformation gauge (SDG) that has many advantages over many of the existing devices and can be readily manufactured in both research and commercial laboratories. The device is based on using a highly flexible, yet very strong metal strip of spring steel secured between two stiff, stainless steel L-shaped legs; the spring strip is provided with four strain gauges. With this arrangement, local deformation of a specimen is transferred into significant bending in the metal strip and elongation or shortening of the strain gauges. In addition to being very cost effective, the SDG is characterized by the ability to control both range and resolution of measured deformation, its linear output, and a clever pinning mechanism that protects it from being damaged when it goes out of range. Success of the SDG was demonstrated in a true K0 test on carbonate sand.

Meshless Simulation of Fracture in Thin-Walled Pipe Structures

2009 ◽  
Author(s):  
S. J. Liu
Keyword(s):  
Dynamic Fracture ◽  
Fracture Criterion ◽  
Sph Method ◽  
Shell Analysis ◽  
Stress Point ◽  
Particle Hydrodynamics ◽  
Thin Walled Pipe ◽  
Smoothed Particle ◽  
Point Integration ◽  
Thin Walled

A meshless shell method for dynamic fracture problems based on normalized Smoothed Particle Hydrodynamics (SPH) is presented. The SPH method is corrected by a normalization in order to fulfill completeness requirement. Instability are controlled by stress-point integration. The method is modified for Mindlin-Reissner shell analysis. Stress based fracture criterion is incorporated based on the visibility method. The method is applied to two dynamic fracture problems in thin-walled pipes including fluid-structure interaction. The results are compared to experimental data and they are very promising.

Multi-Scale Overlapping Domain Decomposition to Consider Local Deformations in the Analysis of Thin-Walled Members

2014 ◽  
Vol 553 ◽  
pp. 667-672
Author(s):  
R. Emre Erkmen
Keyword(s):  
Numerical Technique ◽  
Global Analysis ◽  
Local Deformation ◽  
Local Analysis ◽  
Type Model ◽  
Cross Sectional ◽  
Multi Scale ◽  
Shell Type ◽  
Thin Walled ◽  
The Cross

Thin-walled members that have one dimension relatively large in comparison to the cross-sectional dimensions are usually modelled by using beam-column type finite element formulations. Beam-column elements however, are based on the assumption of rigid cross-section, thus they cannot consider the cross-sectional deformations such as local buckling and only allows considerations of the beam axis behaviour such as flexural or lateral-torsional buckling. Shell-type finite elements can be used to model the structure in order to consider these local deformation effects. Based on the Bridging multi-scale approach, this study proposes a numerical technique that is able to split the global analysis, which is performed by using simple beam-type elements, from the local analysis which is based on more sophisticated shell-type elements. As a result, the proposed multi-scale method allows the usage of shell elements in a local region to incorporate the local deformation effects on the overall behaviour of thin-walled members without necessitating a shell-type model for the whole member.

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