Effects of Air Tightness Tests on Steel Thin-Wall Box Structures with Circular and Rectangular Cross Sections

2019 ◽  
Vol 24 (4) ◽  
pp. 04019029
Author(s):  
G. Campione
Keyword(s):  
Cross Sections ◽  
Thin Wall ◽  
Box Structures ◽  
Air Tightness

scholarly journals Self-Inductance of the Circular Coils of the Rectangular Cross-Section with the Radial and Azimuthal Current Densities

Physics ◽  
2020 ◽  
Vol 2 (3) ◽  
pp. 352-367
Author(s):  
Slobodan Babic ◽  
Cevdet Akyel
Keyword(s):  
Cross Sections ◽  
Special Functions ◽  
Rectangular Cross Section ◽  
The Self ◽  
Thin Wall ◽  
Elementary Functions ◽  
Special Cases ◽  
Current Densities ◽  
New Formula ◽  
Azimuthal Current

In this paper, we give new formulas for calculating the self-inductance for circular coils of the rectangular cross-sections with the radial and the azimuthal current densities. These formulas are given by the single integration of the elementary functions which are integrable on the interval of the integration. From these new expressions, we can obtain the special cases for the self-inductance of the thin-disk pancake and the thin-wall solenoids that confirm the validity of this approach. For the asymptotic cases, the new formula for the self-inductance of the thin-wall solenoid is obtained for the first time in the literature. In this paper, we do not use special functions such as the elliptical integrals of the first, second and third kind, nor Struve and Bessel functions because that is very tedious work. The results of this work are compared with already different known methods and all results are in excellent agreement. We consider this approach novel because of its simplicity in the self-inductance calculation of the previously-mentioned configurations.

Increasing the Production Accuracy of Profile Bending with Methods of Computational Intelligence

2009 ◽  
Vol 17 (4) ◽  
pp. 561-576 ◽  
Author(s):  
Alessandro Selvaggio ◽  
Uwe Dirksen ◽  
A. Erman Tekkaya ◽  
Marco Schikorra ◽  
Matthias Kleiner
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Closed Loop ◽  
Fuzzy Controller ◽  
Structure Optimization ◽  
Quality Criteria ◽  
Closed Loop Control ◽  
Software System ◽  
Thin Wall ◽  
Loop Control

Important quality criteria for profile bending are an accurate profile contour and an accurate cross section. During the bending process, torsion of the profile, deformation of the cross section, and deviations at the profile contour can occur. If these undesired effects are too large, the bent profile is not usable. Critical causes of profile cross section deformation are thin wall thicknesses with hollow sections. The profile torsion is favored by asymmetrical profile cross sections. These effects can be minimized by a production-correct profile design, whereby a trade-off between a production-correct design and the boundary conditions exists. Furthermore, undesired variations in the profile material properties and the profile cross section lead to deviations in the profile contour. These deviations cannot be reduced by design but by usage of a closed-loop control during bending. In this article, a software system for three-roll bending is presented that minimizes undesirable effects during bending by structure optimization of the profile cross section and application of closed-loop control. The structure optimization is based on an evolutionary algorithm and the process control uses a neuro-fuzzy controller. The structure of the software system and results of experiments are presented and discussed. 1

Energy Absorption of Thin Walled Members Under Axial Compressive Loading

2014 ◽  
Author(s):  
Eboreime Ohioma ◽  
Muhammad Ali ◽  
Khairul Alam
Keyword(s):  
Energy Absorption ◽  
Cross Sections ◽  
Compressive Loading ◽  
Thin Wall ◽  
Analysis Software ◽  
Element Analysis ◽  
Cross Sectional ◽  
Compressive Loads ◽  
Thin Walled ◽  
Deformation Modes

This study was conducted to investigate the effects of cross-sectional geometry on thin wall axial crushing members for the purpose of improved energy absorption. A total of five geometrically equivalent shapes (same wall thickness area, material, and length) were analyzed namely, triangle, rectangle, square, pentagon, and circle. The deformation modes and energy absorption of the members were studied under compressive loads and compared using ABAQUS/Explicit module, finite element analysis software. The simulations revealed that for the five geometrically equivalent cross sections under equal loading conditions, the pentagon shaped member absorbed the highest amount of energy. As compared to baseline rectangle member, the pentagon member absorbed approximately 25–28% more energy.

scholarly journals The Fast and Accurate Calculation of the Self Inductance for the Circular Coils of the Rectangular Cross Section with the Radial and the Azimuthal Current Densities

2020 ◽  
Author(s):  
Slobodan Babic ◽  
Cevdet Akyel
Keyword(s):  
Cross Sections ◽  
Special Functions ◽  
Rectangular Cross Section ◽  
The Self ◽  
Thin Wall ◽  
Elementary Functions ◽  
Special Cases ◽  
Current Densities ◽  
New Formula ◽  
Azimuthal Current

In this paper we give the new formulas for calculating the self-inductance for the circular coils of the rectangular cross sections with the radial and the azimuthal current densities. These formulas are given by the single integration of the elementary functions which are integrable on the interval of the integration. From these new expressions we can obtain the special cases for the self-inductance of the thin disk pancake and the thin wall solenoid that confirm the validity of this approach. For the asymptotic cases, the new formula for the self-inductance of the thin wall solenoid is obtained for the first time in the literature. In this paper we do not use special functions such as the elliptical integrals of the first, second and third kind, Struve, and Bessel functions because that is very tedious work. The results of this work are compared with already different known methods and all results are in the excellent agreement. This is way we consider this approach as the novelty because of its simplicity in the self -inductance calculation of the previously mentioned configurations.

On Torsion of Closed Thin-Wall Members With Arbitrary Stress-Strain Laws: A General Criterion for Cross Sections Exhibiting No Warping

2000 ◽  
Vol 67 (3) ◽  
pp. 460-464 ◽  
Author(s):  
A. Chiskis ◽  
R. Parnes
Keyword(s):  
Shear Stress ◽  
Cross Sections ◽  
Small Strain ◽  
Constant Thickness ◽  
General Criterion ◽  
Thin Wall ◽  
Stress Strain

Warping due to torsion of closed thin-wall elastic members having constant thickness is investigated under the assumption of small strain but with arbitrary isotropic shear stress-strain laws. Based on a derived general criterion, it is shown that there exists a class of cross-sections which undergo no warping. For cases where warping exists, an example of simplified calculations, using the derived expressions, is presented for warping of a thin-wall rectangle. [S0021-8936(00)03503-0]

Bending Instability of a General Cross Section Thin-Wall Tube for Minimal Radius of Curvature Passage

2014 ◽  
Vol 81 (10) ◽  
Author(s):  
Hadas Ziso ◽  
Moshe Shoham
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Elastic Stability ◽  
Radius Of Curvature ◽  
Thin Wall ◽  
Sharp Corner ◽  
Initial Cross Section ◽  
Pure Bending ◽  
Section Shape ◽  
Minimal Radius

This paper describes an analytical tool for the design of thin-wall tubes for passage through minimal radius of curvature trajectory. The design is based on a model of thin-wall tube buckling under pure bending. An extended analytical solution for general initial cross section is found based on Brazier method by energy theory of elastic stability. The model predicts the critical moment, curvature, flattening, and stress and allows choosing the most suitable cross section shape for a specific purpose. For example, tubes with ocular and rounded-ocular cross sections were found suitable for semiflexible applications such as endoscopy, where they elastically cross a sharp corner.

scholarly journals Optimal Shakedown of the Thin-Wall Metal Structures Under Strength and Stiffness Constraints

2017 ◽  
Vol 25 (2) ◽  
pp. 25-41
Author(s):  
Piotr Alawdin ◽  
Liudas Liepa
Keyword(s):  
Cross Sections ◽  
Optimization Problem ◽  
Optimization Problems ◽  
Thin Wall ◽  
Lateral Torsional Buckling ◽  
Static Loads ◽  
Metal Structures ◽  
Buckling Behavior ◽  
Plane Frames ◽  
Strength And Stiffness

Abstract Classical optimization problems of metal structures confined mainly with 1st class cross-sections. But in practice it is common to use the cross-sections of higher classes. In this paper, a new mathematical model for described shakedown optimization problem for metal structures, which elements are designed from 1st to 4th class cross-sections, under variable quasi-static loads is presented. The features of limited plastic redistribution of forces in the structure with thin-walled elements there are taken into account. Authors assume the elastic-plastic flexural buckling in one plane without lateral torsional buckling behavior of members. Design formulae for Methods 1 and 2 for members are analyzed. Structures stiffness constrains are also incorporated in order to satisfy the limit serviceability state requirements. With the help of mathematical programming theory and extreme principles the structure optimization algorithm is developed and justified with the numerical experiment for the metal plane frames.

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

Direct Observation of Heat Exchanger Deposits by Cross Sectioning

1967 ◽  
Vol 25 ◽  
pp. 364-365
Author(s):  
R. W. Anderson ◽  
D. L. Senecal
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heat Exchanger ◽  
Direct Observation ◽  
Cross Sections ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Flowing Water ◽  
Transmission Electron ◽  
Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

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