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.

Study on non-local effects in dimers of circular and elliptical cross-sections

2021 ◽  
Author(s):  
Xi Zhang ◽  
Wenyuan Wu ◽  
Yanchun Gong ◽  
Suhong He ◽  
Fangping Wu ◽  
...  
Keyword(s):  
Absorption Spectrum ◽  
Electric Field ◽  
Cross Section ◽  
Cross Sections ◽  
Field Enhancement ◽  
Radius Of Curvature ◽  
Electric Field Enhancement ◽  
Nonlocal Effects ◽  
Elliptical Cross ◽  
Non Local

Abstract The nonlocal effects of dimers consisted of two cylinders are studied, whose cross section is elliptical. Importantly, the results with dimers whose cross section is circular are compared. For comparison, the curvature of the ellipse is set the same with the circle, and four different geometries are considered. The electric field enhancement at the gap center and the absorption spectrum of the dimers are calculated. For the second geometry, either the electric field enhancement at the gap center or the absorption spectrum is approximately calculated using the first geometry, the frequencies corresponding to the peaks are totally different. Similarly, for the fourth geometry, either the electric field enhancement at the gap center or the absorption spectrum is approximately calculated using the third geometry, the disciplines of the peak values change as radius of curvature increases are totally different.

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

Cross Section Optimization of Plane Truss among Different Spans

2014 ◽  
Vol 679 ◽  
pp. 1-5 ◽  
Author(s):  
Sumayah Abdulsalam Mustafa ◽  
Mohd Zulham Affandi bin Mohd Zahid ◽  
Md.Hadli bin Abu Hassan
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Element Analysis ◽  
Cross Sectional ◽  
Analysis And Design ◽  
Cross Section Shape ◽  
Design Variables ◽  
Section Shape ◽  
Steel Sections ◽  
Research Show

Cross sectional areas optimization is to be implemented to study the influence of the cross section shape on the optimum truss weight. By the aid of analysis and design engines with advanced finite element analysis that is the steel design software STAAD. Four rolled steel sections (angle, tube, channel, and pipe) which are used in industrial roof trusses are applied for comparison. Many previous studies, use the areas of cross sections as design variables without highlight to the shape of cross section at the start of the process, consequently the result area will be adequate if the designer choose the effective shape than others. Results of this research show that the chosen cross section shape has a significant impact on the optimum truss weight for same geometry of truss type under the same circumstances of loading and supports.

Parametric Study of Reinforced Concrete Column Cross-Section for Strength and Ductility

2008 ◽  
Vol 400-402 ◽  
pp. 269-274 ◽  
Author(s):  
Naveed Anwar ◽  
Mohammad Qaasim
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Cross Sections ◽  
Strain Curve ◽  
Concrete Column ◽  
Loading Conditions ◽  
Reinforced Concrete Column ◽  
Section Shape ◽  
And Performance ◽  
Strength And Ductility

Several parameters and corresponding performance of reinforced concrete column cross-sections of different shapes (square, rectangular, circular, T-shape, I-shape, cross-shape, L-shape and C-shape) under various loading conditions have been studied in order to determine the suitable and optimum cross-sections for strength and ductility. In each cross-section shape, parameters include compressive strength of concrete (f’c), tensile strength of steel (fy), steel ratio (As/Ag), and angle of bending. In order to demonstrate the behavior and performance of the sections in terms of strength and ductility, CSISectionBuilder software was used to define the stress-strain curve for concrete and steel and then compute the moment-curvature relationship for each section. Considering different sections, the number of parameters in every section and various loading conditions, a total of around 1,800 sections were analyzed. The comparison procedures started within each section shape, and then across different sections in order to determine the most suitable cross-section for strength and ductility. Results of the study are deemed very useful in the system selection and preliminary design of important structures such as buildings with complicated geometry and high architectural demand including bridge piers and hydraulic structures.

Eleocharis compressa × Eleocharis erythropoda, a new natural hybrid spike rush from Ontario

1994 ◽  
Vol 72 (6) ◽  
pp. 837-842 ◽  
Author(s):  
P. M. Catling
Keyword(s):  
Surface Roughness ◽  
Cross Section ◽  
Cross Sections ◽  
Roughness Length ◽  
Putative Hybrid ◽  
Natural Hybrid ◽  
Surface Roughness Length ◽  
Hybrid Plants ◽  
Section Shape ◽  
Spike Rush

Partially sterile plants from eastern Ontario are identified as Eleocharis compressa × Eleocharis erythropoda on the basis of intermediacy in perianth bristle length, tubercle shape, achene surface roughness, length of rhizome internodes, culm cross-section shape, and length of terminal lobes of scales. Both putative parents occurred with the hybrid plants. The hybrid plants had tardily deciduous scales and either bifid or trifid styles. They superficially resemble E. erythropoda most closely but differ markedly in their scaly rhizomes with shorter internodes 3.8 – 7 mm long. They are most readily distinguished from E. compressa by their elliptic or broadly rectangular culm cross sections and some perianth bristles exceeding 0.5 mm in length. This putative hybrid involves taxa in different subseries that would normally be regarded as too distantly related to permit hybridization. Key words: Eleocharis compressa, Eleocharis erythropoda, Cyperaceae, hybrid, taxonomy, classification.

scholarly journals Inductance gradient and current density distribution for T-shaped convex and concave rail cross-sections

2018 ◽  
Vol 7 (1.8) ◽  
pp. 237
Author(s):  
M. N. Saravana Kumar ◽  
R. Murugan ◽  
Poorani Shivkumar
Keyword(s):  
Density Distribution ◽  
Cross Section ◽  
Cross Sections ◽  
Current Density ◽  
Current Density Distribution ◽  
Design Parameters ◽  
Element Analysis ◽  
Analysis Technique ◽  
Section Shape ◽  
Uniform Current

Rectangular rail was the most widely used cross section shape for the rail gun electromagnetic launching (EML) system. Based on sector assimilation, the rail gun key parameter especially current density (J) and inductance gradient (L’) greatly affected. J decides the efficiency of EML and L’ decides the force acting on the projectile of EML. So, it is mandatory to look upon the sector assimilation of rails. In this paper T shape convex and concave shape rail cross section is proposed and rail gun key design parameters are calculated by varying its dimensions using Ansoft Maxwell 2-D eddy current solver which uses finite element analysis technique to calculate these parameters. The performance of rail gun discussed using the obtained values and it has been observed and that the compared with other considered rail geometries, the T-shaped concave model shows more impact on inductance value which causes uniform current density distribution over the rails.

scholarly journals Flexural Behaviour of Lightweight Foamed Concrete Beams Reinforced with GFRP Bars

2018 ◽  
Vol 4 (2) ◽  
pp. 278 ◽  
Author(s):  
Suhad M Abd ◽  
Dhamyaa Ghalib
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Analytical Formula ◽  
Analytical Equation ◽  
Shear Stresses ◽  
Concentrated Load ◽  
Section Shape ◽  
Foamed Concrete ◽  
Show Difference ◽  
The Cross

A three meter-length cantilever beam loaded with a concentrated load at its free end is studied to determine shear stresses. In the present study, three cross sections are considered: rectangle (R); I, and T. The study presents a comparison of maximum shear stresses obtained by means of two methods: classical analytical equation derived by Collingnon, and finite element method (FEM) software. Software programs ANSYS and SAP2000 were used. The results show difference between the maximum shear stresses obtained by the analytical equation and the software, being the last is always higher. The average differences for ANSYS and SAP2000, independently of the cross section, were 12.76% and 11.96%, respectively. Considering these differences, correction factors were proposed to the classical analytical formula for each cross section case to obtain more realistic results. After the correction, the average differences decrease to 1.48% and 4.86%, regardless of the cross section shape.

scholarly journals The Pulsed Electron Beam Time-of-flight Method for Measuring Absolute Total Cross Sections: Atomic Helium

1982 ◽  
Vol 35 (5) ◽  
pp. 559 ◽  
Author(s):  
Robert K Jones ◽  
RA Bonham
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Total Electron ◽  
Pulsed Electron Beam ◽  
Section Shape ◽  
The Cross ◽  
Scattering Cross Sections ◽  
Time Of Flight Method ◽  
New Procedures ◽  
Better Than

Improvements in a previously reported experimental method have made it possible to obtain absolute total electron-scattering cross sections with a predicted accuracy of better than � 2 % (10') for certain electron kinetic energies. As a first example of the application of the new procedures the cross section for helium is reported from O' 8 to 50� 0 eV. Error estimates for all known sources of uncertainty are discussed in detail. The results confirm the earlier work of Kennerly and Bonham and the agreement is, on the average, better than 1 % with no changes in the cross-section shape.

Effect of Cross Sectional Shape on the Energy Absorbing Characteristics of a Tube under Quasi-Static Loading

2013 ◽  
Vol 315 ◽  
pp. 334-338 ◽  
Author(s):  
Jaffar S. Mohamed Ali ◽  
Kassim A. Abdullah ◽  
Yulfian Aminanda
Keyword(s):  
Energy Absorption ◽  
Axial Compression ◽  
Cross Section ◽  
Cross Sections ◽  
Cross Sectional ◽  
Tube Cross Section ◽  
Deformation Response ◽  
Section Shape ◽  
Energy Absorbing ◽  
Sectional Shape

In this study, numerical simulation of tubes of various cross section under axial compression is carried out using LS-DYNA. The effect of varying configurations of tube cross-section shape on the deformation response, collapse mode and energy absorption characteristics of tubes under quasi-static axial compression have been studied. The validation of the finite element tube model was made by comparison with the experimental results of the square tube subjected to quasi-static axial compression. Tabulated results are presented and plots have been included for the specific energy absorption for different cross sections. The study provides an insight on ways to increasing energy absorption of light weight aluminium tubes.

Investigation of Reduction in Buckling Capacity of Cylindrical Shells Under External Pressure Due to Partially Cut Ring Stiffeners

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Snehankush Chikode ◽  
Nilesh Raykar
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Cylindrical Shells ◽  
External Pressure ◽  
Geometrical Parameters ◽  
Section Shape ◽  
Clear Guideline ◽  
Section Viii ◽  
Special Circumstances ◽  
Division 2

Circumferential ring stiffeners are commonly used to improve the buckling strength of cylindrical shells. Under special circumstances, stiffener ring needs to be partially cut in order to avoid interference with vessel attachments or surrounding structures. No clear guideline is available in rule-based method to deal with such case. This paper investigates the extent of reduction in buckling capacity for a range of cylindrical shell geometries with stiffener rings having different cross sections and different extents of circumferential cut. Finite-element (FE)-based analysis as per ASME Section VIII, Division 2, Part 5 has been employed to determine the permissible external pressure in each of the cases. Effects of ring cross section and extent of circumferential cut of stiffening ring on the maximum permissible external pressure have been presented. A total of 63 combinations of shell-stiffening ring configurations of different L/D, D/t ratios, cross section shape, and extent of cut have been investigated. Geometrical parameters for these combinations under study are so chosen that normal working range in industries is covered. The results obtained provide guidelines to design shells with partially cut stiffening rings.

Sign in / Sign up

Export Citation Format

Share Document