The plastic loss of stability of a thin-walled tube under axial compression

2012 ◽  
Vol 76 (3) ◽  
pp. 358-366 ◽  
Author(s):  
R.I. Nepershin
Keyword(s):  
Axial Compression ◽  
Loss Of Stability ◽  
Thin Walled Tube ◽  
Thin Walled

Experimental-numerical test of open section composite columns stability subjected to axial compression

2017 ◽  
Vol 84 (2) ◽  
pp. 58-64 ◽  
Author(s):  
P. Różyło
Keyword(s):  
Axial Compression ◽  
Cross Section ◽  
Critical State ◽  
Critical Loads ◽  
Composite Structures ◽  
Load Capacity ◽  
Numerical Test ◽  
Approximation Methods ◽  
Loss Of Stability ◽  
Thin Walled

Purpose: The aim of the work was to analyse the critical state of thin-walled composite profiles with top-hat cross section under axial compression. Design/methodology/approach: The purpose of the work was achieved by using known approximation methods in experimental and finite element methods for numerical simulations. The scope of work included an analysis of the behavior of thin-walled composite structures in critical state with respect to numerical studies verified experimentally. Findings: In the presented work were determined the values of critical loads related to the loss of stability of the structures by using well-known approximation methods and computer simulations (FEM analysis). Research limitations/implications: The research presented in the paper is about the potential possibility of determining the values of critical loads equivalent to loss of stability of thin-walled composite structures and the future possibility of analyzing limit states related to loss of load capacity. Practical implications: The practical approach in the actual application of the described specimen and methodology of study is related to the necessity of carrying out of strength analyzes, allowing for a precise assessment of the loads upon which the loss of stability (bifurcation) occurs. Originality/value: The originality of the research is closely associated with used the thinwalled composite profile with top-hat cross-section, which is commonly used in the fuselage of passenger airplane. The methodology of simultaneous confrontation of the obtained results of critical loads by using approximation methods and using the linear eigenvalue solution in numerical analysis demonstrates the originality of the research character. Presented results and the methodology are intended for researchers, who are concerned with the topic of loss of stability of thin-walled composite structures.

scholarly journals Crushing Behavior of Thin-Walled Hexagonal Tubes with Partition Plates

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Dai-Heng Chen ◽  
Kenichi Masuda
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Axial Compression ◽  
Compressive Load ◽  
Full Length ◽  
Compression Load ◽  
Thin Walled Tube ◽  
Thin Walled ◽  
Crushing Behavior ◽  
Element Method

The crushing behaviour of hexagonal thin-walled tube with partition plates subjected to axial compression is studied by using finite element method. It is found that, in the crushing process, the folds, which generate along the full length of the tube, come to be crushed simultaneously and the compressive load will not descend, since the compressive load produced in the central part does not descend with the folds forming on outer walls. Therefore, in order to suppress a fluctuation of the compression load in crushing of the tube and to raise its average compression load, it is an effective method to introduce corner parts, especially corner parts where three plates intersect, in the geometry of the thin-walled tube.

NICROBRAZ 50

Alloy Digest ◽  
1994 ◽  
Vol 43 (8) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Honeycomb Structures ◽  
Thin Walled Tube ◽  
Thin Walled ◽  
Low Solubility

Abstract NICROBRAZ 50 is a low-melting, free-flowing filter metal for honeycomb structures and thin-walled tube assemblies. It has low solubility. This datasheet provides information on composition, physical properties, and hardness. It also includes information on corrosion resistance as well as joining. Filing Code: Ni-460. Producer or source: Wall Colmonoy Corporation.

scholarly journals Optimal Design of the Shape of a Non-Ball Mandrel for Thin-Walled Tube Small Radius Cold Bending

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1221
Author(s):  
Lu Bai ◽  
Jun Liu ◽  
Ziang Wang ◽  
Shuanggui Zou
Keyword(s):  
Ideal Point ◽  
Small Radius ◽  
Grey Wolf Optimizer ◽  
Forming Quality ◽  
Hollow Section ◽  
Cold Bending ◽  
Bending Process ◽  
Before And After ◽  
Thin Walled Tube ◽  
Thin Walled

In the field of cold bending, it is necessary to use ball mandrels, especially to bend thin-walled tubes with a small radius. However, the bending process with a ball mandrel is complex and expensive, and it is easy to jam the core ball inside the tube. To solve these issues, we designed two kinds of hollow non-ball mandrel schemes with low stiffness that were suitable for the small radius bending of thin-walled tubes. We evaluated the forming quality of cold bending numerically and the influence of the hollow section length and thickness on the forming indices. Our results showed that the thickness of the hollow section has a greater influence on forming quality than the length. As the hollow section’s thickness increased, the wrinkling rate first declined by approximately 40% and then increased by above 50%. When the thickness was 11 mm in scheme 1 and 13 mm in scheme 2, the wrinkling rate reached minimum values of 1.32% and 1.50%, respectively. As the hollow section’s thickness increased, the flattening rate decreased by more than 60% and the thinning rate increased by about 40%. A multi-objective optimization of forming indices was carried out by ideal point method and grey wolf optimizer. By comparing the forming results before and after optimization, the feasibility of using the proposed hollow mandrel was proved, and the hollow mandrel scheme of standard cylinder is therefore recommended.

scholarly journals Cold Forging Effect on the Microstructure of Motorbike Shock Absorbers Fabricated by Tube Forming in a Closed Die

2021 ◽  
Vol 11 (5) ◽  
pp. 2142
Author(s):  
Trung-Kien Le ◽  
Tuan-Anh Bui
Keyword(s):  
Material Flow ◽  
Cold Forging ◽  
Technological Parameters ◽  
Forming Process ◽  
Tube Forming ◽  
Shock Absorbers ◽  
Thin Walled Tube ◽  
Thin Walled ◽  
Quality Of Products ◽  
Forming Defects

Motorbike shock absorbers made with a closed die employ a tube-forming process that is more sensitive than that of a solid billet, because the tube is usually too thin-walled to conserve material. During tube forming, defects such as folding and cracking occur due to unstable tube forming and abnormal material flow. It is therefore essential to understand the relationship between the appearance of defects and the number of forming steps to optimize technological parameters. Based on both finite element method (FEM) simulations and microstructural observations, we demonstrate the important role of the number and methodology of the forming steps on the material flow, defects, and metal fiber anisotropy of motorbike shock absorbers formed from a thin-walled tube. We find limits of the thickness and height ratios of the tube that must be held in order to avoid defects. Our study provides an important guide to workpiece and processing design that can improve the forming quality of products using tube forming.

ELASTIC BUCKLING OF THIN-WALLED CIRCULAR TUBES CONTAINING AN ELASTIC INFILL

2006 ◽  
Vol 06 (04) ◽  
pp. 457-474 ◽  
Author(s):  
M. A. BRADFORD ◽  
A. ROUFEGARINEJAD ◽  
Z. VRCELJ
Keyword(s):  
Axial Compression ◽  
A Priori ◽  
Local Buckling ◽  
Steel Tube ◽  
Transcendental Equation ◽  
Buckling Mode ◽  
Buckling Stress ◽  
Elastic Tubes ◽  
Thin Walled ◽  
Energy Formulation

Circular thin-walled elastic tubes under concentric axial loading usually fail by shell buckling, and in practical design procedures the buckling load can be determined by modifying the local buckling stress to account empirically for the imperfection sensitive response that is typical in Donnell shell theory. While the local buckling stress of a hollow thin-walled tube under concentric axial compression has a solution in closed form, that of a thin-walled circular tube with an elastic infill, which restrains the local buckling mode, has received far less attention. This paper addresses the local buckling of a tubular member subjected to axial compression, and formulates an energy-based technique for determining the local buckling stress as a function of the stiffness of the elastic infill by recourse to a transcendental equation. This simple energy formulation, with one degree of buckling freedom, shows that the elastic local buckling stress increases from 1 to [Formula: see text] times that of a hollow tube as the stiffness of the elastic infill increases from zero to infinity; the latter case being typical of that of a concrete-filled steel tube. The energy formulation is then recast into a multi-degree of freedom matrix stiffness format, in which the function for the buckling mode is a Fourier representation satisfying, a priori, the necessary kinematic condition that the buckling deformation vanishes at the point where it enters the elastic medium. The solution is shown to converge rapidly, and demonstrates that the simple transcendental formulation provides a sufficiently accurate representation of the buckling problem.

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