Buckling Research Papers - Academia.edu (original) (raw)

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- Steel Structure, Fatigue, Stress analysis, Ansys

Lightweight thin-walled cylindrical shells subjected to external loads are prone to buckling rather than strength failure. The buckling of an axially compressed shell is studied using analytical, numerical and semi-empirical models. An analytical model is developed using the classical shell small deflection theory. A semi-empirical model is obtained by employing experimental correction factors based on the available test data in the theoretical model. Numerical model is built using ANSYS finite element analysis code for the same shell. The comparison reveals that the analytical and numerical linear model results match closely with each other but are higher than the empirical values. To investigate this discrepancy, non-linear buckling analyses with large deflection effect and geometric imperfections are carried out. These analyses show that the effects of non-linearity and geometric imperfections are responsible for the mismatch between theoretical and experimental results. The effect of shell thickness, radius and length variation on buckling load and buckling mode has also been studied. Copyright © 2009 John Wiley & Sons, Ltd.

- by Himayat Ullah
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- Engineering, Modeling, Finite element method, Buckling

Steel structural elements with web-tapered I cross section, are usually made of welded thin plates. Due to the nonrectangular shape of the element, thin web section may be obtained at the maximum cross section height. The buckling strength is directly influenced by lateral restraining, end support and initial imperfections. If no lateral restraints, or when they are not effective enough, the global behavior of the members is characterized by the lateral torsional mode and interaction with sectional buckling modes may occur. Actual design codes do not provide a practical design approach for this kind of elements. The paper summarizes an experimental study performed by the authors on a relevant number of elements of this type. The purpose of the work was to evaluate the actual behavior of the web tapered beam-columns when applying different types of lateral restraints and different web thickness.

- by Editor IJRET
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- Mechanical Engineering, Civil Engineering, Structural Engineering, Investigation

The stability of comparatively more slender decks of under-deck cable-stayed bridges is studied, by considering both the critical loads and the post-buckling behaviour. A potential energy approach is applied to a simplified discrete link and spring model that allows for an exact nonlinear formulation of the equilibrium equations. The physical response is found to be dependent on the ratio of the axial stiffness of the cable-staying system to the flexural stiffness of the deck. The influence of several parameters is analysed and unstable mode interaction is observed to occur under certain geometric conditions. The presented analytical model is compared with a nonlinear finite element model that shows good correlation. Finally, some design criteria and recommendations are suggested, which are relevant for designers of this innovative typology of cable-stayed bridges.

- by Fernando Madrazo-Aguirre and +1
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- Applied Mathematics, Mechanics, Structural Engineering, Solid Mechanics
- by Metin Aydogdu
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- Engineering, Modeling, Vibration, Higher Order Thinking

Local buckling is a failure mode commonly observed in thin-walled structural steel elements. Even though its effect on their behaviour at ambient temperature conditions is well documented and incorporated in current design codes, this is not the case when such elements are exposed to fire. This paper focuses on the occurrence of local buckling in steel members at elevated temperatures by conducting a thorough review of the literature. Experimental data (over 400 in total) gathered from 16 different sources are presented for both hot-formed as well as cold-formed elements made from different cross-sectional geometries (rolled or welded H-sections, box sections, channels etc). The effect of local buckling (and the various parameters that influence it) on the failure temperature is discussed based on the collected experimental evidence. Finally, the methods (numerical modelling and proposed analytical expressions) used by different authors to understand this phenomenon for steel members exposed to fire are discussed.

The use of continuous variables for cross-sectional dimensions in truss structural optimization gives solutions with a large number of different cross sections with specific dimensions which in practice would be expensive, or impossible to create. Even slight variations from optimal sizes can result in unstable structures which do not meet constraint criteria. This paper shows the influence of the use of discrete cross section sizes in optimization and compares results to continuous variable counterparts. In order to achieve the most practically applicable design solutions, Euler buckling dynamic constraints are added to all models. A typical space truss model from literature, which use continuous variables, is compared to the discrete variable models under the same conditions. The example model is optimized for minimal weight using sizing and all possible combinations of shape and topology optimizations with sizing.

- by Nenad Petrovic and +2
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- Engineering, Mechanical Engineering, Structural Engineering, Structural Optimization
- by Alaa E Elwi
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- Civil Engineering, Finite Element, Residual Stresses, Buckling

The complex problem of truss structural optimization, based on the discrete design variables assumption, can be approached through optimizing aspects of sizing, shape, and topology or their combinations. This paper aims to show the differences in results depending on which aspect, or combination of aspects of a standard 10 bar truss problem is optimized. In addition to standard constraints for stress, cross section area, and displacement, this paper includes the dynamic constraint for buckling of compressed truss elements. The addition of buckling testing ensures that the optimal solutions are practically applicable. An original optimization approach using genetic algorithm is verified through comparison with literature, and used for all the optimization combinations in this research. The resulting optimized model masses for sizing, shape, and topology or their combinations are compared. A discussion is given to explain the results and to suggest which combination would be best in a generalized example.

- by Applied Engineering Letters and +2
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- Mechanical Engineering, Optimization (Mathematics), Genetic Algorithms, Structural Optimization
- by Taichiro Okazaki and +2
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- Civil Engineering, Structural Engineering, Buckling
- by IOSR Journals
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- Civil Engineering, Structural Engineering, Buckling, Column

This paper investigates the buckling and postbuckling of simply supported,
nanocomposite plates with functionally graded nanotube reinforcements
subjected to uniaxial compression in thermal environments. The nanocomposite
plates are assumed to be functionally graded in the thickness direction using singlewalled
carbon nanotubes (SWCNTs) serving as reinforcements and the plates’ effective
material properties are estimated through a micromechanical model. The
higher order shear deformation plate theory with a von Kármán-type of kinematic
nonlinearity is used to model the composite plates and a two-step perturbation technique
is performed to determine the buckling loads and postbuckling equilibrium
paths. Numerical results for perfect and imperfect, geometrically mid-plane symmetric
functionally graded carbon nanotube reinforced composite (FG-CNTRC)
plates are obtained under different sets of thermal environmental conditions. The
results for uniformly distributed CNTRC plate, which is a special case in the present
study, are compared with those of the FG-CNTRC plate. The results show that the
buckling loads as well as postbuckling strength of the plate can be significantly
increased as a result of a functionally graded nanotube reinforcement. The results
reveal that the carbon nanotube volume fraction has a significant effect on the buckling
load and postbuckling behavior of CNTRC plates.

- by Zheng H Zhu and +1
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- Mechanics of fiber-reinforced polymer composites for construction, Post buckling, Functionally graded materials, Buckling

The stochastic buckling behaviour of sandwich plates is presented considering uncertain system parameters (material and geometric uncertainty). The higher-order-zigzag theory (HOZT) coupled with stochastic finite element model is employed to evaluate the random first three buckling loads. A cubic in-plane displacement variation is considered for both face sheets and core while quadratic transverse displacement is considered within the core and assumed constant in the faces beyond the core. The global stiffness matrix is stored in a single array by using skyline technique and stochastic buckling equation is solved by simultaneous iteration technique. The individual as well as compound stochastic effect of ply-orientation angle, core thickness, face sheets thickness and material properties (both core and laminate) of sandwich plates are considered in this study. A significant level of computational efficiency is achieved by using artificial neural network (ANN) based surrogate model coupled with the finite element approach. Statistical analyses are carried out to illustrate the results of stochastic buckling behaviour. Normally in case of various engineering applications, the critical buckling load with the least Eigen value is deemed to be useful. However, the results presented in this paper demonstrate the importance of considering higher order buckling modes in case of a realistic stochastic analysis. Besides that, the probabilistic results for global stability behaviour of sandwich structures show that a significant level of variation with respect to the deterministic values could occur due to the presence of inevitable source-uncertainty in the input parameters demonstrating the requirement of an inclusive design paradigm considering stochastic effects.

- by TM TM
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- Buckling, Sandwich composite laminates

In this paper, a generalised complex finite strip method is proposed for buckling analysis of thin-walled cold-formed steel structures. The main advantage of this method over the ordinary finite strip method is that it can handle the shear effects due to the use of complex functions. In addition, distortional buckling as well as all other buckling modes of cold-formed steel sections like local and global modes can be investigated by the suggested complex finite strip method. A combination of general loading including bending, compression, shear and transverse compression forces is considered in the analytical model. For validation purposes, the results are compared with those obtained by the Generalized Beam Theory analysis. In order to illustrate the capabilities of complex finite strip method in modelling the buckling behavior of cold-formed steel structures, a number of case studies with different applications are presented. The studies are on both stiffened and unstiffened cold-formed steel members.

- by Davood Mostofinejad
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- Civil Engineering, Building, Buckling, Building and Construction Materials

This paper is concerned with distortional buckling of cold-formed steel channel sections by the semi-analytical complex finite strip method. The main purpose of this paper is to study the buckling behavior of cold-formed channel sections with extra longitudinal stiffeners at the end of flanges and also on the web. One of the most important purposes of this study is to investigate the optimum width of extra longitudinal flange stiffeners in cold-formed channel sections. Furthermore, the optimum position of longitudinal web stiffeners is calculated to maximize the distortional as well as local buckling strength of cold-formed channel sections. For validation purposes, complex finite strip method results are compared with those obtained by Generalized Beam Theory (GBT) analysis. Using the semi-analytical complex finite strip method, a comparison on the buckling behavior of unstiffened and stiffened cold-formed channel sections in local, distortional and global modes will be done.

- by E. Brunesi and +2
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- Civil Engineering, Finite element method, Storage Tanks, Buckling
- by Juan Virella
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- Civil Engineering, Finite Elements, Finite Element, Stability

This paper describes the application of refined plate theory to investigate free vibration and buckling analyses of functionally graded nanocomposite plates reinforced by aggregated carbon nanotube (CNT). The refined shear deformation plate theory (RSDT) uses four independent unknowns and accounts for a quadratic variation of the transverse shear strains across the thickness, satisfying the zero traction boundary conditions on the top and bottom surfaces of the plate without using shear correction factors. The motion equations are derived from Hamilton's energy principle and Navier's method is applied to solve this equation. The material properties of the functionally graded carbon nanotube reinforced composites (FG-CNTRCs) are assumed to vary along the thickness and estimated with the Mori–Tanaka approach. Effects on the natural frequency and critical buckling load of the FG-CNTRC plates by CNT volume fraction, CNT distribution , CNT cluster distribution, and geometric dimensions of the plate are investigated. Effects of loading conditions on the critical buckling load are also examined.

- by Hossein Malek-Mohammadi
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- Carbon Nanotubes, Nanocomposites, Functionally graded materials, Buckling

In this paper, a semi-analytical finite strip method is developed for the prediction of torsional and flexural buckling stresses of composite FRP columns under pure compression. Numerical finite strip results will be compared with those obtained from closed-form equations for doubly symmetric open thin-walled FRP sections. The accuracy of the proposed finite strip method in determining critical flexural and tor- sional stresses of FRP columns will be assessed. Among the composite FRP columns with doubly symmet- ric open sections, buckling behavior of stiffened and unstiffened FRP cruciform sections will be evaluated and case studies performed. The effect of material properties and longitudinal stiffeners applied at the end of the web-plate and flange-plate on buckling modes of composite FRP cruciform sections is also reviewed.

- by Hamid Naderian and +1
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- Structural Engineering, Finite Element Methods, Composite Materials and Structures, FRP
- by Mortezza Iran
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- Artificial Intelligence, Neural Networks, Genetic Algorithm, Optimization

Dear Prof. Muhammad Masood Rafi Editor-in-Chief NED University Journal of Research The article entitled State based ultimate strength analysis of stiffened panels has been reviewed according to your demand. The evaluation criteria are as follows: 1. the topic of this paper is relevant, timely, and of interest to the audience of this research field. 2. the abstract of the paper is accurate, balanced but it should include the most important findings of the study. 3. the paper has clarity of presentation. it is well organized, clearly written. 4.the quality of the papers cited in this paper is good. 5. the content of this paper is technically accurate and sound. 6. the idea is novel and original. 7. the paper is easy to read and free from grammatical and spelling mistakes. 8. the paper is free from concerns over publication ethics. 9. the verification process needs addition of tables corresponding to the graphs. Therefore, I recommend this paper to be accepted. yours Osama Mohammed Elmardi Suleiman NILE VALLEY UNIVERSITY, ATBARA, SUDAN 1/3/2018

- by Dr. Osama M Elmardi
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- Civil Engineering, Structural Engineering, Buckling
- by Ertugrul Taciroglu
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- Civil Engineering, Plasticity, Structures and Fire Engineering, Finite Element

The present research improves the experimental and theoretical knowledge on the behaviour of structural elements made of ultra high performance fibre reinforced concrete (UHPFRC) with ordinary reinforcement. UHPFRC is a recently developed material with much higher mechanical properties and durability than ordinary concrete. However, it has been used so far in a limited number of structural applications. A better knowledge on the behaviour of UHPFRC in structural members is needed to be able to take advantage of its outstanding properties in structural design. One of the ways in which the structural efficiency of UHPFRC can be studied is to investigate the improvement in structural performance that is gained by using UHPFRC instead of ordinary concrete in common structural members. As an alternative, new structural shapes and structural concepts can be explored, more adapted to the specific material properties. The work presented in this thesis focuses on the first approach by consid...

- by Dario Redaelli
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- Buckling, Confinement, Bond, Column

This work presents an analytical approach to investigate buckling and post-buckling behavior of FGM plate with porosities resting on elastic foundations and subjected to mechanical, thermal and thermomechanical loads. The formulations are based on Reddy's higher-order shear deformation plate theory taking into consideration Von Karman nonlinearity, initial geometrical imperfections, and Pasternak type of elastic foundations. By applying Galerkin method, closed-form relations of buckling loads and post-buckling equilibrium paths for simply supported plates are determined. Numerical results are carried out to show the effects of porosity distribution characteristics (Porosity-I and Porosity-II), geometrical parameters, material properties and elastic foundations on the mechanical, thermal and thermomechanical buckling loads and post-buckling resistance capacity of the porous FGM plates.

- by Minh-Chien Trinh
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- Porous Materials, Porosity, Nonlinear Analysis, Post buckling
- by Massimo Fragiacomo
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- Design Methods, Numerical Modelling, Buckling, TIMBER STRUCTURES

An arch is a curved structure in its elevation, loaded in-plane having supports are prevented from stretching out, and loads are supported mainly in compression. Arches are extensively used in infrastructure projects to provide large span structures, especially in bridges owing to its effective load carrying mechanism. For the case study, a 60m clear span standard bowstring is analyzed. The study has been done for comparison of buckling factor given in Eurocode 3: part 2 with the model analyzed.

- by Ijariit Journal
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- Civil Engineering, Structural Engineering, Buckling, Abaqus

A study of an existing B-pillar was conducted to examine the changes required to increase the lateral load carrying capability by a factor of ten. A finite element optimization package was used to adjust the geometric and material characteristics simultaneously while minimizing weight. The results show that the weight and cost necessary for the ten-fold improvement in lateral load carrying capability were very low. Further, the results illustrate how structural design optimization with finite element modeling can be effectively utilized to create cost effective elements for use in an integrated occupant protection system.

- by Keith Friedman
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- Design, FEM, Finite Elements, Structural

This work experimentally and numerically studies large deflection of slender cantilever beam of linear elastic material, subjected to a combined loading which consists of internal vertical uniformly distributed continuous load and external vertical concentrated load and a horizontal concentrated load at the free end of the beam. We got equations with the help of large deflection theory, and present the differential equation governing the behaviour of this system and show that that this equation, although straightforward in appearance, is in fact rather difficult to solve due to the presence of a non-linear term. A numerical evaluation is used to evaluate the system and calculate Young`s modulus of the beam material. With simple experiment we show, how a Young`s modulus can be obtained and then the phenomenon of the large elastic sideways deflection of a column under compressive loading is investigated and elastica of buckled column is calculated.

- by Ziga Gosar
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- Stability, Buckling, Cantilevers, Cantilever
- by Jie Yang
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- Engineering, Modeling, Edge Detection, Kinematics

Using continuous variables in truss structural optimization results in solutions which have a large number of different cross section sizes whose specific dimensions would in practice be difficult or expensive to create. This approach also creates optimal models which if varied, even slightly, result in structures which do not meet constraint criteria. This research proposes the discretization of cross section sizes to standard sizes of stock produced for the particular cross section and material, and a 1mm precision for node location when using shape optimization. Additionally, Euler buckling constraints are added to all models in order to achieve optimal solutions which can find use in practical application. Several standard test models of trusses from literature, which use continuous variables, are compared to the discrete variable models under the same conditions. Models are optimized for minimal weight using sizing, shape, topology, and combinations of these approaches.

- by Nenad Petrovic and +1
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- Structural Optimization, Topology Optimization, Parametric Design (Architecture), Genetic Algorithm in Optimization
- by Xi-Qiao Feng
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- Engineering, Elasticity, Nanowires, Physical sciences

The present study investigates buckling in functionally graded material (FGM) beams when exposed to a temperature rise. The proposed FGM beams have arbitrary edge supports that are modeled by rotational and translational springs. The mechanical properties are assumed to vary continuously across the thickness direction according to a simple four-parameter power law. To obtain the critical value of temperature, the governing equilibrium equations are extracted based on Timoshenko beam theory, using the assumption of Von-Karman nonlinearity for the physical neutral surface concept. The equations are further solved by Fourier series expansion via Stokes' transformation technique. Numerical examples are provided to demonstrate the accuracy and reliability of the proposed method. The influence of two models of metal-ceramic distribution across the thickness (symmetrical and unsymmetrical ones) on the response of the beam in thermal buckling of FG beam is investigated. It is observed that, the critical buckling temperature rises more for symmetrical model of FGM beam with respected to unsymmetrical one. Also, increasing the translational and rotational spring coefficient makes the beam stiffer; consequently, the critical buckling temperature is increased.

- by Carlos Graciano
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- Civil Engineering, Steel Structure, Finite Element Analysis, Resistance

A model based on a modified couple stress theory for the free vibration and buckling analyses of beams is presented. The model also incorporates the Poisson's effect and allows the analysis of Timoshenko beams with any arbitrary end boundary condition. The natural frequencies and buckling loads are computed using the Ritz method. Parametric studies show that, while the natural frequencies and the buckling loads increase monotonically with the increase of the material length scale, they present a minimum in certain values of the Poisson's ratio. A study relating the classical elasticity and the couple stress strain energies is also presented. By establishing this relation, explicit formulas to obtain the natural frequencies and buckling loads, in which the couple stress and Poisson's effects are accounted for, in terms of the buckling loads of the classical elasticity are found. These formulas, which are valid when the shear strain and stress are zero, allow an expedite computation of natural frequencies and buckling loads of beams with couple stress and Poisson's effect.

- by Amin Lotfi
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- Engineering, Localization, Mathematical Sciences, Physical sciences

Publication Impact Factor (PIF): 1.0 Downloaded @ www.sretechjournal.org Abstract Finite element method (FEM) is utilized to obtain numerical solution of the governing differential equations. Buckling analysis of rectangular laminated plates with rectangular cross – section for various combinations of boundary conditions and aspect ratios is studied. To verify the accuracy of the present technique, buckling loads are evaluated and validated with other works available in the literature. The good agreement with other available data demonstrates the reliability of finite element method used. New numerical results are generated for uniaxial and biaxial compression loading of symmetrically laminated composite plates; they are focused on the significant effects of buckling for various parameters such as boundary condition, aspect ratio and modular ratio. It was found that the effect of boundary conditions on buckling load increases as the aspect ratio increases for both uniaxial and biaxial compression loading. It was also found that, the variation of buckling load with aspect ratio becomes almost constant for higher values of elastic modulus ratio.

- by Dr. Osama M Elmardi
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- Buckling
- by Ahmed Shuraim
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- Civil Engineering, Methodology, Theory, Finite element method
- by Lê Chung
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- Engineering, Modeling, Finite element method, Morphological Analysis
- by Muammer Koç
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- Machine Tools, Manufacturing Engineering, Buckling, Analytical Model

- by Dr. Osama M Elmardi
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- Buckling

In this work, biaxial buckling analysis of sandwich plates with symmetric composite laminated core and two functionally graded nanocomposite face sheets is carried out by a new improved high-order theory. The nanocomposite face sheets are carbon nanotube (CNT)-reinforced nanocomposites and the material properties of the nanocomposites plates are graded along the thickness and are estimated though the Mori–Tanaka approach. CNTs are assumed randomly oriented and aggregated into some clusters. The same third order theory is used for modeling of core and the faces sheets. The theory has third and second orders of z for in-plane and normal displacements, respectively. The principle of minimum potential energy is used to derive the equations of motion and boundary conditions. Analytical solution for static analysis of simply supported sandwich plates under biaxial in-plane compressive loads is presented using Navier's solution. The effects of CNT volume fraction, CNT aggregation states, CNT distribution, biaxial loads ratio, and geometric dimensions of sandwich plate are investigated on the overall buckling of functionally graded carbon nanotube-reinforced nanocomposite sandwich plates.

- by Hossein Malek-Mohammadi and +1
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- Carbon Nanotubes, Nanocomposites, Functionally graded materials, Buckling

This paper proposes a semi analytical complex finite strip method using bubble functions to study the local, distortional and global buckling of stiffened as well as unstiffened cold formed steel I-sections under compression and bending loading conditions. The method is programmed and used to investigate the elastic buckling of mono and doubly symmetric I-sections containing longitudinal flange stiffeners. The effect of longitudinal flange stiffeners on the stability of cold-formed I-section members is surveyed. Furthermore, a comparison between stiffened and unstiffened cold-formed I-sections is made for different buckling modes. The accuracy of bubble finite strip method in predicting the buckling stresses of monosymmetric cold-formed I-section beams in comparison with Generalized Beam Theory (GBT method) will be established. Case studies are performed for different geometric properties of the sections and the stiffeners on the buckling strength of cold-formed steel I-sections.

Publication Impact Factor (PIF): 1.0 Downloaded @ www.sretechjournal.org Abstract Classical plate theory (CPT) is used to study buckling of thin laminated composite plates. Finite element method (FEM) is utilized to obtain numerical solution of the governing differential equations. Buckling analysis of rectangular laminated plates with rectangular cross – section for various combinations of boundary conditions and aspect ratios is studied. To verify the accuracy of the present technique, buckling loads are evaluated and validated with other works available in the literature. The good agreement with other available data demonstrates the reliability of finite element method used. New numerical results are generated for uniaxial and biaxial compression loading of symmetrically laminated composite plates. It was found that the effect of boundary conditions on buckling load increases as the aspect ratio increases for both uniaxial and biaxial compression loading. It was also found that, the variation of buckling load with aspect ratio becomes almost constant for higher values of elastic modulus ratio.

- by Dr. Osama M Elmardi
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- Buckling
- by matin latifi and +2
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- Mechanical Engineering, Civil Engineering, Buckling, Fourier Series