scholarly journals MEMBER GLOBAL BUCKLING STRENGTH ESTIMATION OF SPATIAL TRUSS ROOF WITH SEMI-RIGID JOINTS CONSIDERING BOUNDARY CONDITIONS

2021 ◽  
Vol 86 (786) ◽  
pp. 1235-1246
Author(s):  
Yuki TERAZAWA ◽  
Ryunosuke KISHIZAWA ◽  
Toru TAKEUCHI ◽  
Tomohiko KUMAGAI ◽  
Miao CAO
Keyword(s):  
Boundary Conditions ◽  
Buckling Strength ◽  
Global Buckling ◽  
Rigid Joints

Investigation on Buckling of Cylindrical Shells and Influences of Boundary Conditions

2011 ◽  
Vol 243-249 ◽  
pp. 1326-1330
Author(s):  
Chao Zhang ◽  
Jian Long Ji ◽  
Jian Ping Lei
Keyword(s):  
Boundary Conditions ◽  
Cylindrical Shells ◽  
Structural Elements ◽  
Complex Dynamic ◽  
Absorption Properties ◽  
Axial Impact ◽  
Buckling Strength ◽  
Industrial Sectors ◽  
Thin Walled

Thin-walled cylindrical shells are widely used in many industrial sectors as light structural elements. Determination of their buckling strength under various types of loading conditions is a crucial work for engineering design. Due to the needs of research of crashworthiness, dynamic buckling of cylindrical shells subjected to the strong axial impact becomes a frontier issue in recent years. The axial impact is a very complex dynamic process because of the coupling of multiple effects. In this paper, the buckling mechanism of cylindrical shells subjected to axial impact and the influences of boundary conditions, and energy absorption properties have been investigated by experiments.

Assessment of Parameters Influencing Lateral Buckling of Deep Subsea Pipe-in-Pipe Pipeline System Using Finite Element Modeling

2014 ◽  
Author(s):  
M. Masood Haq ◽  
S. Kenny
Keyword(s):  
Boundary Conditions ◽  
Load Capacity ◽  
External Pressure ◽  
Design Parameters ◽  
Parameter Study ◽  
Pipeline System ◽  
Limit States ◽  
Lateral Buckling ◽  
Global Buckling ◽  
External Forces

The operational requirements for subsea pipeline systems have progressed towards higher design temperatures and pressures (HTHP). To address flow assurance requirements, pipe-in-pipe systems have been developed. For pipelines laid on the seabed, or with partial embedment, the potential for lateral buckling; in response to operational loads, external forces and boundary conditions, has become a major factor in engineering design. The effective axial force is a key factor governing the global lateral buckling response that is influenced by parameters such as internal and external pressure, and operating and ambient temperature. Other design parameters that influence lateral buckling include global imperfections or out-of-straightness, pipe/soil interaction characteristics and installation conditions. Global buckling reduces the axial load capacity of the pipeline that may impair operations and exceed serviceability limit states. Results from a numerical parameter study on lateral buckling response of a subsea pipe-in-pipe (PIP) pipeline are presented. The parameters examined include pipe embedment, pipe out-of-straightness (OOS), soil shear strength, soil peak and residual forces and displacements, variation in soil properties distributed along the pipeline route, and external pressure associated with the installation depth. The observed pipe response was a complex relationship with these parameters and kinematic boundary conditions.

The Effect of Shape, Thickness and Boundary Imperfections on Plastic Buckling of Cones

2011 ◽  
Author(s):  
O. Ifayefunmi ◽  
J. Błachut
Keyword(s):  
Boundary Conditions ◽  
Axial Compression ◽  
Wall Thickness ◽  
Thickness Distribution ◽  
Radial Pressure ◽  
External Pressure ◽  
Combined Loading ◽  
Small Radius ◽  
Worst Case ◽  
Buckling Strength

Three types of imperfections are analysed in the current paper, and they are: (i) Initial geometric imperfections, i.e., deviations from perfect geometry, (ii) Variations in the wall thickness distribution, and (iii) Imperfect boundary conditions. It is assumed that cones are subject to: (a) axial compression only, (b) radial pressure only, and (c) combined loading, i.e., axial compression and external pressure acting simultaneously. Buckling strength of imperfect cones is obtained for all of the cases above. It is shown that the buckling strength is differently affected by imperfections, when cones are subjected to axial compression or to radial external pressure. The response to imperfections along the combined stability envelope is also provided, and these results are first of this type. The finite element analysis, using the proprietary code is used as the numerical tool. Cones are assumed to be from mild steel and the material is modelled as elastic perfectly plastic. Geometrical imperfection profiles are affine to eigenshapes. A number of them are tried in calculations, as well as the effect of them being superimposed. The results indicate that imperfection amplitude and its shape strongly affect the load carrying capacity of conical shells. Also, it is shown that the buckling loads of analyzed cones are more sensitive when subjected to combined loading as compared to their sensitivity under single load conditions. At the next stage, uneven thickness distribution along the cone slant was considered. Variation of wall thickness was assumed to vary in a piece-wise constant fashion. This appears to have a large effect on the buckling strength of cones under axial compression only as compared with that of cones subjected to radial external pressure only. Finally, the effect of variability of boundary conditions on failure load of cones was investigated for two loading conditions, i.e., for axial compression and for radial pressure, only. Results indicate that change of boundary conditions influences the magnitude of buckling load. For axially compressed cones the loss of buckling strength can be large (about 64% for the worst case (beta = 30 deg, the cone not restrained at small radius end). Calculations for radial pressure indicate that the loss of buckling strength is not as acute — with 34% for the worst case (beta = 40 deg, relaxed boundary conditions at the larger radius end). This is an entirely numerical study but references to accompanying experimental programme are provided.

Evaluation of Buckling Performance of Fibre Metal Rectangular Plates: Experimental and Numerical Investigation

2014 ◽  
Vol 575 ◽  
pp. 185-190
Author(s):  
M. Vasumathi ◽  
Murali Vela
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Buckling Load ◽  
Thin Layers ◽  
Maximum Deviation ◽  
Critical Buckling Load ◽  
Buckling Strength ◽  
Different Boundary Conditions ◽  
Simply Supported ◽  
Fibre Metal

Carbon reinforced aluminium laminate (CARAL) is a fibre metal laminate which consists of layers of carbon fibre and thin layers of aluminium. Buckling strength of CARAL under various support conditions is studied in this paper. Since CARAL is composed of fibre and metal, the pattern of failure of the laminate under compressive loads is truly imperative. The compressive buckling strength depends on geometrical parameters like length and width of the specimen and the sequence in which the layers are stacked. It also depends on the boundary condition. In this study, the critical buckling load is determined by varying the parameters such as aspect ratio (length/width), stacking sequence and boundary condition. Two different boundary conditions are considered, simply supported and fixed support condition. Numerical simulation analysis shows a maximum deviation of 16.72% from experimental results. The different failure modes executed by the laminate under compressive loading are also determined. The critical buckling load of CARAL constrained on all sides is evaluated numerically for different boundary conditions. Buckling load, in this case, takes maximum value when CARAL is clamped on all sides whereas it takes minimum value when the plate is simply supported on three sides keeping the fourth side fixed.

scholarly journals Buckling optimisation of sandwich cylindrical panels

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
M. Abouhamzeh ◽  
M. Sadighi
Keyword(s):  
Genetic Algorithm ◽  
Finite Element ◽  
Sheet Thickness ◽  
Optimal Solution ◽  
Finite Element Program ◽  
Buckling Strength ◽  
Cylindrical Panels ◽  
The Face ◽  
Global Buckling ◽  
Element Program

AbstractIn this paper, the buckling load optimisation is performed on sandwich cylindrical panels. A finite element program is developed in MATLAB to solve the governing differential equations of the global buckling of the structure. In order to find the optimal solution, the genetic algorithm Toolbox in MATLAB is implemented. Verifications are made for both the buckling finite element code and also the results from the genetic algorithm by comparisons to the results available in literature. Sandwich cylindrical panels are optimised for the buckling strength with isotropic or orthotropic cores with different boundary conditions. Results are presented in terms of stacking sequence of fibers in the face sheets and core to face sheet thickness ratio.

Using Controlled Global Buckling to Improve Buried Pipelines Performance Under Large Compressive Ground Displacements

2018 ◽  
Author(s):  
Ali Fathi ◽  
Onyekachi Ndubuaku ◽  
Samer Adeeb
Keyword(s):  
Boundary Conditions ◽  
Design Method ◽  
Local Buckling ◽  
Test Results ◽  
Buried Pipelines ◽  
Buckling Mode ◽  
Buried Pipes ◽  
Global Buckling ◽  
Novel Method ◽  
Simulated Field

This paper presents the basic concept and verification tests results of a novel method designed to prevent failures of buried pipelines subjected to compressive deformations which are usually caused by ground movements. In this method the boundary conditions of the buried pipes are modified by installing soft elements next to the pipe before backfilling. With the new boundary conditions, the pipe response under large compressive forces will be in form of a stable global buckling mode with a predefined deformed shape. This behavior prevents rapid increase in the compressive axial force that causes local buckling, wrinkling, and subsequent softening, and strain localization. By using this method, pipes can have an extended compressive hardening response that absorbs large compressive displacements. The evaluation of this concept and its performance level were studied through a series of lab tests on 4-1/2 inch pipe specimens under simulated field conditions. The test results confirmed the anticipated performance of this technique which can evolve into a design method.

A Comparison of Buckling Strength of Y and T Stiffeners in Ship Plating

2008 ◽  
Vol 45 (03) ◽  
pp. 125-131
Author(s):  
Sherif Farouk Badran ◽  
Ashraf O. Nassef ◽  
Sayed M. Metwalli
Keyword(s):  
Boundary Conditions ◽  
Elastic Buckling ◽  
Bottom Flange ◽  
Effective Width ◽  
Buckling Loads ◽  
Buckling Strength ◽  
Hull Girder ◽  
Inland Waterway ◽  
Compressive Loads ◽  
Buckling Coefficient

One aim of naval architects is to design structures that are strong enough and capable of absorbing impact energy. Therefore, ship plates are stiffened using different stiffeners to withstand compressive and other loads resulting from loads due to collisions, stranding, or grounding. There are also uniform stresses that are most typically induced in deck or bottom flange by longitudinal hull girder bending. In this paper, the T stiffener that has been widely used in shipbuilding and the Y stiffener that is starting to be used in inland waterway tankers in The Netherlands are considered. The aim of this paper is to compare the buckling strength of the T and Y stiffeners in combination with the effective width of ship plating under the action of uniformly distributed compressive loads. Two different groups of boundary conditions are considered for both T and Y stiffeners, and the elastic buckling coefficient is obtained and then the critical buckling loads are calculated. The obtained results showed that the critical buckling loads for Y stiffener are larger than that for equivalent T stiffener by about 40% for the first group of boundary conditions. The second group showed that the Y stiffener plate combination is five times stronger in compression than the equivalent T stiffener plate combination.

Use of the Magnetostatic Analogue In Electromagnetic Lens Engineering

1970 ◽  
Vol 28 ◽  
pp. 360-361
Author(s):  
John W. Coleman
Keyword(s):  
Boundary Conditions ◽  
High Performance ◽  
Force Fields ◽  
Optical Design ◽  
Direct Conversion ◽  
Design Engineering ◽  
Design Data ◽  
Scalar Potentials ◽  
Geometric Elements ◽  
At Will

In the design engineering of high performance electromagnetic lenses, the direct conversion of electron optical design data into drawings for reliable hardware is oftentimes difficult, especially in terms of how to mount parts to each other, how to tolerance dimensions, and how to specify finishes. An answer to this is in the use of magnetostatic analytics, corresponding to boundary conditions for the optical design. With such models, the magnetostatic force on a test pole along the axis may be examined, and in this way one may obtain priority listings for holding dimensions, relieving stresses, etc..The development of magnetostatic models most easily proceeds from the derivation of scalar potentials of separate geometric elements. These potentials can then be conbined at will because of the superposition characteristic of conservative force fields.

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