Effect of tube wall thickness on the confinement loss, power fraction and bandwidth of terahertz negative curvature fibers

Optik ◽  
2019 ◽  
Vol 178 ◽  
pp. 717-722 ◽  
Author(s):  
Dexian Yan ◽  
Jiusheng Li
Keyword(s):  
Wall Thickness ◽  
Negative Curvature ◽  
Tube Wall ◽  
Confinement Loss ◽  
Tube Wall Thickness ◽  
Power Fraction

Structural Integrity Assessment of Steam Generator Tubes Using a New EPRI Statistical Approach

2002 ◽  
Author(s):  
Carlos Alexandre de Jesus Miranda ◽  
Miguel Mattar Neto
Keyword(s):  
Steam Generator ◽  
Wall Thickness ◽  
Nuclear Power ◽  
Structural Integrity ◽  
Tube Wall ◽  
New Approach ◽  
Inconel 600 ◽  
Integrity Assessment ◽  
Tube Wall Thickness ◽  
Uniform Tube

A fundamental step in tube plugging management of a Steam Generator (SG), in a Nuclear Power Plant (NPP), is the tube structural integrity evaluation. The degradation of SG tubes may be considered one of the most serious problems found in PWRs operation, mainly when the tube material is the Inconel 600. The first repair criterion was based on the degradation mode where a uniform tube wall thickness corrosion thinning occurred. Thus, a requirement of a maximum depth of 40% of the tube wall thickness was imposed for any type of tube damage. A new approach considers different defects arising from different degradation modes, which comes from the in-service inspections (NDE) and how to consider the involved uncertainties. It is based on experimental results, using statistics to consider the involved uncertainties, to assess structural limits of PWR SG tubes. In any case, the obtained results, critical defect dimensions, are within the regulatory limits. In this paper this new approach will be discussed and it will be applied to two cases (two defects) using typical data of SG tubes of one Westinghouse NPP. The obtained results are compared with ‘historical’ approaches and some comments are addressed from the results and their comparison.

The Formation of Tracheae and Tracheoles in Rhodnius prolixus

1958 ◽  
Vol s3-99 (45) ◽  
pp. 29-46
Author(s):  
M. LOCKE
Keyword(s):  
Axial Compression ◽  
Wall Thickness ◽  
Tube Wall ◽  
Rhodnius Prolixus ◽  
Axial Orientation ◽  
Tube Wall Thickness ◽  
Walled Cylinder ◽  
Tangential Orientation

The formation of tracheae in Rhodnius is described by the hypothesis of expansion and buckling. The cuticulin lining is at first a smooth-walled cylinder. Later it expands equally in each direction, increasing in diameter but buckling in the axis. An engineering expression describing symmetrical buckling in a cylinder under uniform axial compression has been applied to this process. Agreement was obtained between the expected and observed values for buckling frequency and tube-wall thickness. The taenidia are formed within the buckles, their amplitude being proportional to the increase in diameter. The axial orientation of the chitin micelles in the lining membrane and the tangential orientation in the taenidia are consistent with their being oriented by the stresses expected during expansion and buckling. The formation of tracheoles may also be described by the expansion and buckling hypothesis.

Experimental and Numerical Studies on Flexural Behavior of Casing Joint of Square Steel Tube

2010 ◽  
Vol 163-167 ◽  
pp. 417-420
Author(s):  
Min Ding ◽  
Zhen Hua Hou ◽  
Xiu Gen Jiang ◽  
Yu Zhi He ◽  
Guang Kui Zhang ◽  
...  
Keyword(s):  
Wall Thickness ◽  
Failure Modes ◽  
Shear Failure ◽  
Tube Wall ◽  
Edge Length ◽  
Steel Tube ◽  
Flexural Behavior ◽  
Flexural Capacity ◽  
Tube Wall Thickness ◽  
Square Steel Tube

The tests on thirteen specimens of casing joints of square steel tube were conducted to investigate the flexural behavior of the joints. And numerical simulation studies on that were carried out by ANSYS/LS-DYNA. On this basis, effects of tube wall thickness, tube edge length, and inserting depth on failure mode, ultimate flexural capacity and deformation of the joints were discussed. The results show that there are two types of failure modes, i.e., inside tube yield failure and outside tube shear failure. Ultimate flexural capacity and rigidity of the joints increased with the inserting depth increasing. The ultimate flexural capacity is proportional to tube shear strength, tube wall thickness, inserting depth, and tube edge length.

Numerical Simulation Studies on Tension Behavior of Casing and Dowel Joint of Square Steel Tube

2010 ◽  
Vol 156-157 ◽  
pp. 1555-1558
Author(s):  
Min Ding ◽  
Zhen Hua Hou ◽  
Xiu Gen Jiang ◽  
Zi Chen Lin ◽  
Guang Kui Zhang ◽  
...  
Keyword(s):  
Wall Thickness ◽  
Failure Modes ◽  
Tube Wall ◽  
Tensile Load ◽  
Steel Tube ◽  
Element Analysis ◽  
Tube Wall Thickness ◽  
Dowel Joint ◽  
Square Steel Tube ◽  
Tube Failure

The study on tension behavior of casing and dowel joint of square steel tube was carried out by using finite element analysis software ANSYS/LS-DYNA with consideration of geometric nonlinearity, material nonlinearity and contact nonlinearity. On this basis, the effects of inside tube wall thickness, main tube wall thickness, and inserting depth on failure mode, ultimate tensile load and deformation of casing and dowel joint of square steel tube was discussed. The results show that there are three types of failure modes, i.e., bolt failure, inside tube failure and main tube failure, when the joints are subjected to axial tension force. Compare to the joint with the same wall thickness of inside tube and main tube, the reduction of wall thickness of inside tube or main tube will weaken greatly the ultimate tensile load of the joint. The ultimate tensile load of casing and dowel joints is proportional to bolt shear strength, tube wall thickness, inserting depth, and tube edge length. The fruits are useful to the design and application of casing and dowel joints of square steel tube.

An Evaluation System of Tube Wall Thickness of Feed Water Heater Base on the Advanced NDE Technique

2008 ◽  
Author(s):  
Seiichi Hamada ◽  
Takahisa Uchikura ◽  
Kouichi Morisaki
Keyword(s):  
Data Acquisition ◽  
Wall Thickness ◽  
Evaluation System ◽  
Tube Wall ◽  
Digital Data ◽  
Evaluation Methodology ◽  
Metal Loss ◽  
Feed Water ◽  
Pulse Technique ◽  
Tube Wall Thickness

The inspection of the tubes of feed water heaters on the wall thickness is generally conducted using the ultrasonic pulse technique. According to the past method, the wall thickness at each measured point is evaluated in comparison with the minimum required wall thickness of the tube, namely it is based on the general metal loss evaluation criteria. However, these tubes often show the local metal loss due to erosion and corrosion. Evaluation techniques and acceptance criteria regarding the locally thinned tubes require many wall thickness data around the local metal loss locations. However, it is inefficient to perform this evaluation work with human power because of the required huge measured data. With recent improvement of the inspection technique, technology enabled faster, larger amount, and more accurate electronic digital data acquisition of tube wall thickness. The authors have developed the systematized evaluation methodology that can transact data acquisition and evaluation simultaneously. This paper describes the logic of evaluation methods and examined algorithms to make them systematized.

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