scholarly journals Ultimate Load-Carrying Ability of Rib-Stiffened 2024-T3 and 7075-T6 Aluminium Alloy Panels under Axial Compression

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1176
Author(s):  
Ján Slota ◽  
Andrzej Kubit ◽  
Tomasz Trzepieciński ◽  
Bogdan Krasowski ◽  
Ján Varga
Keyword(s):  
Axial Compression ◽  
Single Point ◽  
Local Buckling ◽  
Image Correlation ◽  
Structural Elements ◽  
Compression Tests ◽  
Buckling Modes ◽  
Stiffened Panels ◽  
Load Carrying ◽  
Different Thickness

Stringer-stiffened panels made of aluminium alloys are often used as structural elements in the aircraft industry. The load-carrying capacity of this type of structure cannot relieve the reduction in strength in the event of local buckling. In this paper, a method of fabrication of rib-stiffened panels made of EN AW-2024-T3 Alclad and EN AW-7075-T6 Alclad has been proposed using single point incremental forming. Panels made of sheets of different thickness and with different values of forming parameters were tested under the axial compression test. A digital image correlation (DIC)-based system was used to find the distribution of strain in the panels. The results of the axial compression tests revealed that the panels had two distinct buckling modes: (i) The panels buckled halfway up the panel height towards the rib, without any appreciable loss of rib stability, and (ii) the rib first lost stability at half its height with associated breakage, and then the panel was deflected in the opposite direction to the position of the rib. Different buckling modes can be associated with the character of transverse and longitudinal springback of panels resulting from local interaction of the rotating tool on the surface of the formed ribs.

scholarly journals Confinement effects for rubberised concrete in tubular steel cross-sections under combined loading

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
A. Mujdeci ◽  
D. V. Bompa ◽  
A. Y. Elghazouli
Keyword(s):  
Axial Compression ◽  
Cross Section ◽  
Cross Sections ◽  
Image Correlation ◽  
Combined Loading ◽  
Test Results ◽  
Compression Tests ◽  
Confinement Effects ◽  
Rubber Content ◽  
Dependent Modification

AbstractThis paper describes an experimental investigation into confinement effects provided by circular tubular sections to rubberised concrete materials under combined loading. The tests include specimens with 0%, 30% and 60% rubber replacement of mineral aggregates by volume. After describing the experimental arrangements and specimen details, the results of bending and eccentric compression tests are presented, together with complementary axial compression tests on stub-column samples. Tests on hollow steel specimens are also included for comparison purposes. Particular focus is given to assessing the confinement effects in the infill concrete as well as their influence on the axial–bending cross-section strength interaction. The results show that whilst the capacity is reduced with the increase in the rubber replacement ratio, an enhanced confinement action is obtained for high rubber content concrete compared with conventional materials. Test measurements by means of digital image correlation techniques show that the confinement in axial compression and the neutral axis position under combined loading depend on the rubber content. Analytical procedures for determining the capacity of rubberised concrete infilled cross-sections are also considered based on the test results as well as those from a collated database and then compared with available recommendations. Rubber content-dependent modification factors are proposed to provide more realistic representations of the axial and flexural cross-section capacities. The test results and observations are used, in conjunction with a number of analytical assessments, to highlight the main parameters influencing the behaviour and to propose simplified expressions for determining the cross-section strength under combined compression and bending.

Collapse of Tubes Under Combined Bending and Axial Compression Loads

2018 ◽  
Author(s):  
Shan Jin ◽  
Shuai Yuan ◽  
Yong Bai
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Axial Compression ◽  
Local Buckling ◽  
Practical Application ◽  
Buckling Modes ◽  
Combined Loads ◽  
Bending Loads ◽  
Good Agreement

In practical application, pipelines will inevitably experience bending and compression during manufacture, transportation and offshore installation. The mechanical behavior of tubes under combined axial compression and bending loads is investigated using experiments and finite element method in this paper. Tubes with D/t ratios in the range of 40 and 97 are adopted in the experiments. Then, the ultimate loads and the local buckling modes of tubes are studied. The commercial software ABAQUS is used to build FE models to simulate the load-shortening responses of tubes under combined loads. The results acquired from the ABAQUS simulation are compared with the ones from verification bending experiment, which are in good agreement with each other. The models in this paper are feasible to analyze the mechanical properties of tubes under combined axial compression and bending loads. The related results may be of interest to the manufacture engineers.

Post-buckling Behavior of Stiffened Cross-Ply Cylindrical Shells

1994 ◽  
Vol 61 (4) ◽  
pp. 998-1000 ◽  
Author(s):  
M. Savoia ◽  
J. N. Reddy
Keyword(s):  
Axial Compression ◽  
Carrying Capacity ◽  
Shell Theory ◽  
Load Carrying Capacity ◽  
Imperfection Sensitivity ◽  
Buckling Modes ◽  
Geometric Imperfection ◽  
Buckling Behavior ◽  
Load Carrying ◽  
Post Buckling

The post-buckling of stiffened, cross-ply laminated, circular determine the effects of shell lamination scheme and stiffeners on the reduced load-carrying capacity. The effect of geometric imperfection is also included. The analysis is based on the layerwise shell theory of Reddy, and the “smeared stiffener” technique is used to account for the stiffener stiffness. Nu cylinders under uniform axial compression is investigated to merical results for stiffened and unstiffened cylinders are presented, showing that imperfection-sensitivity is strictly related to the number of nearly simultaneous buckling modes.

Experiment on T-Shaped CFT Stub Columns with Binding Bars Subjected to Axial Compression

2013 ◽  
Vol 838-841 ◽  
pp. 439-443 ◽  
Author(s):  
Zhi Liang Zuo ◽  
Da Xin Liu ◽  
Jian Cai ◽  
Chun Yang ◽  
Qing Jun Chen
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
Failure Modes ◽  
Local Buckling ◽  
Steel Tube ◽  
Steel Plates ◽  
Buckling Modes ◽  
Cft Column ◽  
Stub Columns ◽  
Strength And Ductility

To improve the mechanical behavior of T-shaped concrete-filled steel tubular (T-CFT) column, the method that setting binding bars along the height of steel tube is proposed. Five T-CFT stub columns with binding bars and another two without binding bars subjected to axial compression were tested. The influences of the spacing and diameter of binding bars on the failure modes, maximum strength, and ductility of T-CFT stub columns are investigated. The experimental results demonstrate that by setting binding bars or decreasing the spacing of binding bars, the buckling modes of the steel plates are changed, the local buckling of the steel plates is postponed, and the confinement effects on the core concrete can be improved significantly. By setting binding bars, the bearing capacity and ductility of the columns are enhanced by 1.17 and 3.38 times at most, respectively. By increasing the diameter of binding bars, the ductility of the columns is improved, but the bearing capacity and buckling strength cannot be improved when the diameter is large enough.

Local Buckling of Axially Compressed, Pultruded GRP, WF-Section, Short Columns - Comparison of Experimental and FE Analysis Buckling Loads

2004 ◽  
Vol 1-2 ◽  
pp. 87-92 ◽  
Author(s):  
G.J. Turvey ◽  
Y. Zhang
Keyword(s):  
Local Buckling ◽  
Compression Tests ◽  
Dimensional Model ◽  
Column Buckling ◽  
Buckling Loads ◽  
Buckling Modes ◽  
Short Columns ◽  
Bending Strain ◽  
Reinforced Plastic ◽  
Longitudinal Elastic Modulus

The results of axial compression tests carried out on four pultruded GRP (Glass Reinforced Plastic) WF (Wide Flange) short columns are presented. The longitudinal elastic modulus, buckling loads and collapse loads have been obtained. The experimental buckling loads have been evaluated from the load versus end shortening (axial displacement) relationship and Southwell plots of deflection and bending strain test data. FE (Finite Element) buckling analyses of the short column buckling tests have also been carried out. It is shown that a two-dimensional model is able to predict local buckling modes accurately and buckling loads reasonably accurately.

scholarly journals Theoretical design of innovative cold formed steel beam sections

2015 ◽  
Vol 3 (2) ◽  
pp. 255
Author(s):  
M. Adil Dar ◽  
Deepankar K. Ashish ◽  
A. R. Dar
Keyword(s):  
Construction Industry ◽  
Load Carrying Capacity ◽  
Structural Elements ◽  
Buckling Modes ◽  
Steel Sheets ◽  
Modes Of Failure ◽  
Theoretical Design ◽  
Load Carrying ◽  
Cold Formed Steel ◽  
Hot Rolled

<p>In today’s world, the construction industry both structural and non-structural elements are fabricated from thin gauges of steel sheets. These thin walled sections are being used as columns, beams, joists, studs, floor decking, built-up sections and other components for lightly loaded structures. Unlike hot rolled sections, the design of Cold-Formed Steel (CFS) section for beam is predominantly controlled by various buckling modes of failure, thereby drastically reducing their load carrying capacity. Hence there is an urgent need in the CFS industry to look beyond the conventional CFS beam sections and investigate newly proposed innovative CFS beam sections, which seem to prove structurally much more efficient. Prior to any experimental investigation of innovative beam sections, there is a need to carry out theoretical design using some of the most appropriate available methods applicable to the case under consideration. This paper focuses on such theoretical designs for various innovative sections using available analytical design tools together with appropriate codal guidelines.</p>

scholarly journals Maximum Load Carrying Capacity Estimation of The Ship and Offshore Structures by Progressive Collapse Approach

2016 ◽  
Vol 23 (3) ◽  
pp. 28-38 ◽  
Author(s):  
Hasan Ölmez ◽  
Ertekin Bayraktarkatal
Keyword(s):  
Progressive Collapse ◽  
Longitudinal Axis ◽  
Maximum Load ◽  
Offshore Structures ◽  
Structural Elements ◽  
Stiffened Panels ◽  
Smith Method ◽  
Load Carrying ◽  
Collapse Analysis ◽  
Progressive Collapse Analysis

Abstract The aim of the paper is to represent step by step progressive collapse analysis for maximum load carrying capacity estimation of a hull girder by using variant of Smith Method, named HULT by authors, with different element separation including single plates, stiffeners, hard corners and stiffened panels. The structural elements that form the ships and offshore structures are exposed to large vertical bending moments and especially compression or tension forces in the longitudinal axis in case of hogging and sagging under bad sea conditions. In recent years, it becomes very important and valuable to practically, fast and nearly correct estimation of the maximum vertical bending moment just before breaks in two (collapse) under the worst conditions. The optimum (accuracy, time, practicality) estimation of these values depend on how accurate the stress-strain relation of the structural elements are established. In this first part of study, the ultimate strength behaviour of the stiffened panels in decks, bottoms and sides is estimated by developed semi-analytical method with updated orthotropic panel calculation approach under uniaxial (only longitudinal axis) compression loads. The second part of calculation is focused on the progressive collapse analysis of hull girders under longitudinal uniaxial compression with Smith Method but with different element discretization in contrast to the conventional beam-column elements. Also some benchmark studies of such methods on ultimate limit state assessment of stiffened panels and nine benchmark hull girders of ships are conducted, using some candidate methods such as IACS Common Structural Rules (CSR), FEA with Ansys v13 and HULT prepared by authors. The results from the tests, FEM analysis and different computational approaches are compared to determine performance of the method.

Confinement of Masonry Columns with PBO FRCM Composites

2014 ◽  
Vol 624 ◽  
pp. 644-651 ◽  
Author(s):  
Christian Carloni ◽  
Claudio Mazzotti ◽  
Marco Savoia ◽  
Kolluru V. Subramaniam
Keyword(s):  
Carrying Capacity ◽  
Brick Masonry ◽  
Image Correlation ◽  
Load Carrying Capacity ◽  
Fiber Reinforced ◽  
Compression Tests ◽  
Frp Composites ◽  
Load Carrying ◽  
The Matrix ◽  
The One

The overarching goal of this work is to provide a fundamental understanding of the behavior of solid brick masonry columns confined with fiber reinforced cementitious matrix (FRCM) composites. FRCM is a newly-developed type of composite material comprised of a cementitious inorganic matrix (binder) and embedded fibers that are usually bundled to improve the bond between the matrix and the fibers. Compression tests were carried out to investigate the influence of the FRCM confinement and the brick patterns on the load-carrying capacity of the confined columns. Compression tests were conducted on brick masonry columns with different brick configurations. Digital image correlation measurements on the surface of the composite and on the surface of the brick for the control specimens were attempted in order to understand the role of the mortar joints and the arch effect across the section of the columns due to the confinement. The experimental results indicate that FRCM composites can effectively increase the load-carrying capacity of brick masonry columns and the failure mode could be different from the one observed for masonry columns confined with fiber-reinforced polymer (FRP) composites.

An Analytical Buckling Load Formula for a Cylindrical Shell Subjected to Local Axial Compression

2021 ◽  
Author(s):  
Licai Yang ◽  
Yuguang Li ◽  
Tian Qiu ◽  
Yuanyuan Dong ◽  
Shanglin Zhang
Keyword(s):  
Cylindrical Shell ◽  
Galerkin Method ◽  
Axial Compression ◽  
Analytical Formula ◽  
Local Buckling ◽  
Pressure Vessels ◽  
Buckling Load ◽  
Perfect Agreement ◽  
Buckling Modes ◽  
The Galerkin Method

Abstract This paper proposes an analytical buckling load formula for a cylindrical shell subjected to local axial compression for the first time, which is achieved by a carefully constructed load description and perturbation procedure. Local axial load is described by introducing an arctangent function firstly. Then, the analytical solutions of local buckling load coefficients and buckling modes for a locally compressed shell are derived after solving governing differential equations by the perturbation method. For validation, using the presented analytical buckling modes, the Galerkin method is applied to obtain numerical result, which is an infinite order determinant about local buckling load coefficient. Comparative calculation results show that local buckling load coefficients by the analytical formula are in perfect agreement with numerical ones by the Galerkin method and known results in literature. Therefore, the validity and accuracy of the presented formula are verified. Engineering application of the analytical formula is also discussed to evaluate local buckling loads of thin-walled cylindrical shell structures such as silos, pressure vessels, large storage tanks and so on.

scholarly journals Stereo-DIC Measurements of a Vibrating Bladed Disk: In-Depth Analysis of Full-Field Deformed Shapes

2021 ◽  
Vol 11 (12) ◽  
pp. 5430
Author(s):  
Paolo Neri ◽  
Alessandro Paoli ◽  
Ciro Santus
Keyword(s):  
Single Point ◽  
Excitation Frequency ◽  
Phase Variation ◽  
Operating Conditions ◽  
Image Correlation ◽  
Response Analysis ◽  
Full Field ◽  
Low Speed ◽  
Bladed Disk ◽  
Depth Analysis

Vibration measurements of turbomachinery components are of utmost importance to characterize the dynamic behavior of rotating machines, thus preventing undesired operating conditions. Local techniques such as strain gauges or laser Doppler vibrometers are usually adopted to collect vibration data. However, these approaches provide single-point and generally 1D measurements. The present work proposes an optical technique, which uses two low-speed cameras, a multimedia projector, and three-dimensional digital image correlation (3D-DIC) to provide full-field measurements of a bladed disk undergoing harmonic response analysis (i.e., pure sinusoidal excitation) in the kHz range. The proposed approach exploits a downsampling strategy to overcome the limitations introduced by low-speed cameras. The developed experimental setup was used to measure the response of a bladed disk subjected to an excitation frequency above 6 kHz, providing a deep insight in the deformed shapes, in terms of amplitude and phase distributions, which could not be feasible with single-point sensors. Results demonstrated the system’s effectiveness in measuring amplitudes of few microns, also evidencing blade mistuning effects. A deeper insight into the deformed shape analysis was provided by considering the phase maps on the entire blisk geometry, and phase variation lines were observed on the blades for high excitation frequency.

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