Post buckling Research Papers - Academia.edu (original) (raw)

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- by
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- Physics, Humanities, Model Order Reduction, Post buckling

Cette these s’inscrit dans le cadre de l’etude du post-flambement local des grandes struc- tures composites raidies. La simulation du post- flambement par la methode des elements- finis est aujourd’hui limitee par le cout du calcul en particulier pour les grandes structures. Seules des zones restreintes peuvent etre etudiees, en negligeant les interactions global/local. L’objectif de cette these est de proposer une strategie de calcul performante pour la simula- tion du post-flambement local des grandes structures raidies a partir des connaissances sur le comportement mecanique des structures en post-flambement et d’un decoupage naturel le long des raidisseurs favorable au calcul parallele.Dans la litterature, les methodes de reduction de modele adaptative ont demontre leur ca- pacite a reduire le nombre d’inconnues tout en maitrisant l’erreur d’approximation de la solution des problemes non-lineaires. Par ailleurs, les methodes de decomposition de do- maine avec localisation non-li...

- by ludovic barriere
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- Physics, Humanities, Model Order Reduction, Post buckling
- by ludovic barriere
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The load carrying capacity, buckling and post-buckling behavior of cylindrical thin-walled shells exposed to axial loads are very sensitive to imperfections in the initial geometry. These imperfections are invariably caused by an assortment of manufacturing processes like displacing, installing or welding; one of the most important imperfections caused by welding that has been reported to have an essential detrimental effect on the buckling resistance of these shells under axial load is circumferential imperfections. Despite many determinations of the effect of imperfections on axial load carrying capacity of cylindrical thin-walled shells, the major part of these studies are concentrated on the existence of imperfections on the shell wall, and a comprehensive research on circumferential imperfections and their effects on axial load carrying capacity has not been performed. This is the main subject of this research. Also in this paper, the interaction of two imperfections on each other and on the load carrying capacity of cylindrical shells in various cases are analyzed and determined using a finite element program (ABAQUS).

- by Journal of Ferdowsi Civil Engineering
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- Post buckling, Buckling, Non-Linear Analysis
- by Mamadou Tall
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- Mechanical Engineering, Civil Engineering, Aerospace Engineering, Materials Science

Functionally graded materials (FGM) are increasingly used in the engineering field. In many applications, FGMs are modelled as plates. Plate made of functionally graded materials (FGPs) are mostly designed to perform under elevated temperatures. In those circumstances, they are often under the combined effect of thermal and mechanical loads. There have been many studies on buckling analysis of FGP under either mechanical or thermal loads; however, only a few studies have addressed the combined effect of both loads acting together. This article focuses on the review of research on buckling analysis of FGP under the combined thermal and mechanical loads.

- by Ahmed Hassan
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- Materials Science, Structural Engineering, Buckling, Thermal

- by Ahmed Hassan
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- Materials Science, Structural Engineering, Buckling, Thermal
- by isaac elishakoff
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- Mechanical Engineering, Civil Engineering, Mathematics, Finite element method
- by Dheeraj Varma
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- Engineering, Materials Science, Clutch, Engineering Technology

A more accurate analytical approximate expression for the slope at any point of the elastic curve of a slender cantilever column is obtained by using a heuristic but pedagogical derivation. This derivation is based on the linearization of the nonlinear differential equation that governs the post-buckling of the cantilever column. The expression proposed depends on two unknown parameters, which are obtained by comparing, term by term, the power series expansions of the approximate and exact expressions for the total length of the column. The results obtained with this new approximate expression are compared with the exact ones and with two approximations previously published in the literature. The numerical results show that the two previous approximations are not nearly as accurate as the new expression presented in this paper.

- by Sergi Gallego i Rico
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- Engineering, Mathematics, Education, Post buckling
- by Farid Abed-Meraim
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- Mechanical Engineering, Civil Engineering, Mathematics, Computer Science
- by Dragan Milasinovic
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- Materials Science, Structural Engineering, Buckling, Finite Strip Method
- by Nicola Rizzi
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- Mechanical Engineering, Civil Engineering, Aerospace Engineering, Mathematics

In the present study, the electro-mechanical responses of smart laminated composite plates with piezoelectric materials are derived using a two-dimensional (2 D) displacement-based non-polynomial higher-order shear deformation theory. The kinematics of the mathematical model incorporates the deformation of laminates which account for the effects of transverse shear deformation and a non-linear variation of the in-plane displacements using inverse sine hyperbolic function of the thickness coordinate. The equilibrium equations are obtained using the minimization of energy principle known as the principle of minimum potential energy (PMPE) which is also based on a variational approach and the solutions are obtained using Navier’s solution technique for diaphragm supported smart laminated composite plates. The responses obtained in the form of deflection and stresses are compared with three dimensional (3 D) solutions and also with different polynomial and non-polynomial based higher-or...

- by Dr. Rosalin Sahoo
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- Mechanical Engineering, Materials Science

- by Ahmed Hassan
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- Materials Science, Structural Engineering, Buckling, Thermal

This paper deals with the dynamic response of Functionally Graded Material (FGM) plates resting on a viscoelastic foundation under dynamic loads. The governing equations are derived by using Hamilton’s principle using the classical plate theory and the higher-order shear deformation plate theory. Using state-space methods to find the closed-form solution of the dynamic response of functionally graded rectangular plates resting on a viscoelastic foundation. Numerical examples are given for displacement and stresses in the plates with various structural parameters and the effects of these parameters are discussed. The result of the numerical example shows a marked decrease in displacement and stresses as the coefficient of viscous damping is increased.

- by Dang Thuy
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- Viscoelasticity, Plate Theory
- by Piotr Paczos
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- Materials Science, Structural Engineering, Finite element method, Bending

In the present study, an accurate Bézier based multi-step method is developed and implemented to find the nonlinear vibration and post-buckling configurations of Euler-Bernoulli composite beams reinforced with graphene nano-platelets (GnP). The GnP is assumed to be randomly and uniformly dispersed in the composite mixproportion, with a random checkerboard configuration. Therefore, a probabilistic model together with an efficient simulation technique is proposed to find the effective moduli of a matrix reinforced GnP. It is worth noting that the presented micro-mechanics model found by the employed Monte-Carlo simulation matches exactly the experimental data and predicts the composite elastic constants more accurate than that found from other common methods, including the Halpin-Tsai theory. Also, for mathematical simplification, the composite beam in-plane inertia is neglected. The presented multi-step method is based on Burnstein polynomial basis functions while shows interesting potential to provide robust solutions for various initial and boundary value problems. It is found that adding a relatively low content of GnP would drastically increase the composite elastic constants, particularly in the transverse direction to fiber. In addition, the numerical results are compared with those provided by exact analytical solutions, where the stability of results suggests the effectiveness of the presented methodology.

- by Hossein Kabir
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- Graphene, Numerical Analysis, Composite Materials, Nanotechnology

This paper presents an exact mathematical model for the postbuckling of a uniformly heated slender rod with axially immovable simply supported ends on the basis of geometrically nonlinear theory of extensible rods. The material is assumed linear elastic and its thermal strain-temperature relationship is considered nonlinear. Two approaches have been used in this study. The first approach is based on the extensible elastica theory. The governing equations are derived and solved analytically for the exact closed form solutions that include the equilibrium configurations of the rod, equilibrium paths, and temperature gradients. The exact solutions take the form of elliptic integrals of the first and second kinds. In the second approach, the multisegment integration technique is employed to solve a set of nonlinear differential equations with the associated boundary conditions. The equations are integrated by using the Runge-Kutta algorithm. A comparison study between the analytical ell...

- by Shayak Faruqui
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- Mechanical Engineering, Mathematics, Materials Science, Linear Elasticity
- by Mostafa Baghani
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- Engineering, Materials Science, Structural Engineering, Finite element method
- by Reza Rahgozar
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- Materials Science, Structural Engineering, Corrosion

In this work the Bubnov-Galerkin variational method was applied to determine the critical buckling load for the elastic buckling of columns with fixed-pinned ends. Coordinate shape functions for Euler column with fixed-pinned ends are used in the Bubnov-Galerkin variational integral equation to obtain the unknown parameters. One parameter and two parameter shape functions were used. In each case, the Bubnov-Galerkin method reduced the boundary value problem to an algebraic eigen-value problem. The solution of the characteristic homogeneous equations yielded the buckling loads. One parameter coordinate shape function yielded relative error of 4% compared with the exact solution. Two parameter coordinate shape function gave a relative error of 0.77%, which is negligible.

- by Ike Charles
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- Engineering, Mathematics, Mathematical Analysis, Buckling
- by Morteza Dardel
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- Mechanical Engineering, Materials Science, Vibration, Shape Memory Alloy
- by Hui-Shen Shen
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- Mechanical Engineering, Civil Engineering, Aerospace Engineering, Materials Science
- by Petri Varsta
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- Engineering, Structural Engineering, Composite structures, Bending
- by Petri Varsta
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- Psychology, Materials Science
- by Marcílio da Rocha Freitas
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- Engineering, Mathematics, Structural Engineering, Calibration
- by Behrooz Karimi
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- Materials Engineering, Materials Science, Carbon Nanotube, Vibration
- by Hamed Bagheri
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- Mechanical Engineering, Mathematics, Materials Science, Buckling

Here, analytical studies have been carried out to determine the optimal values of effective parameters on the stress concentration factor around a cutout using genetic algorithm. Optimum designs of single lamina as well as symmetric laminates with 4, 8 and 12 layers of graphite/epoxy and glass/epoxy plates containing a circular cutout with various sizes are presented. The work focuses on extending the analytical solution given by Greszczuk to determine the stress distribution in multilayered composite plates subjected to arbitrary in-plane loadings. This is achieved by introducing an arbitrary oriented uniaxial, biaxial and shear loading conditions into Greszczuk solution. In order to mimic as much as possible the real structural behavior, the finite-width correction factor given by Tan is used. Effective parameters on stress distribution around the circular cutout in composite plates considered as design variables include: load angle, fiber orientation, cutout size and stacking seq...

- by Giovanni Zucco
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- Engineering, Mechanical Engineering, Civil Engineering, Aerospace Engineering
- by Khaled Hariz
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- by Nicola L Rizzi
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- Mathematics, Applied Mathematics, Computer Science, Symbolic Computation

We investigate the buckling of a ‘Roorda’ frame by means of a direct one-dimensional beam model. The frame is acted upon by a ‘dead’ load at the joint and is constrained there by an out-of-plane linear elastic spring. The possibility of warping constraints at the beam ends is also considered; the spring simulates the presence of braces in actual 3D frames. The numerical results are compared with those already obtained by the authors for an infinitely stiff spring.

- by Nicola L Rizzi
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- Materials Science, Buckling
- by Nicola L Rizzi
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- Mechanical Engineering, Civil Engineering, Aerospace Engineering, Mathematics
- by Yogesh Kajale
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- Materials Science, Structural Engineering, Precast Concrete, Stiffness
- by Bajram Shefkiu
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- Materials Science, Structural Engineering, Finite element method, Buckling
- by Bajram Shefkiu
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- Materials Science, Structural Engineering, Geotechnical Engineering, Stiffness
- by Bajram Shefkiu
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- Geology, Structural Engineering, Buckling, Pile

As soft robotic systems grow in complexity and functionality, the size and stiffness of the needed control hardware severely limits their application potential. Alternatively, functionality can be embodied within actuator characteristics, drastically reducing the amount of peripherals. Functions such as memory, computation and energy storage then result from the intrinsic mechanical behavior of precisely designed structures. Here, we introduce actuators with tuneable characteristics to generate complex actuation sequences from a single input. Intricate sequences are made possible by harnessing hysteron characteristics encoded in the buckling of a cone-shaped shell incorporated in the actuator design. A large variety of such characteristics are generated by varying the actuator geometry. We map this dependency and introduce a tool to determine the actuator geometry that yields a desired characteristic. Using this tool, we create a system with six actuators that plays the final movement of Beethoven’s Ninth Symphony with a single pressure supply.

- by Bert Van Raemdonck
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- Robotics, Embodiment, Piano Music, Post buckling

The dynamic behavior of functionally graded (FG) sandwich beams resting on the Pasternak elastic foundation under an arbitrary number of harmonic moving loads is presented by using Timoshenko beam theory, including the significant effects of shear deformation and rotary inertia. The equation of motion governing the dynamic response of the beams is derived from Lagrange’s equations. The Ritz and Newmark methods are implemented to solve the equation of motion for obtaining free and forced vibration results of the beams with different boundary conditions. The influences of several parametric studies such as layer thickness ratio, boundary condition, spring constants, length to height ratio, velocity, excitation frequency, phase angle, etc., on the dynamic response of the beams are examined and discussed in detail. According to the present investigation, it is revealed that with an increase of the velocity of the moving loads, the dynamic deflection initially increases with fluctuations...

- by Monsak Pimsarn
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- Physics, Mechanics, Vibration, Moving Load
- by Said Hariri
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- Mechanical Engineering, Civil Engineering, Aerospace Engineering, Materials Science
- by Noël Challamel
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- Mechanical Engineering, Civil Engineering, Mathematics, Applied Mathematics

Single-walled carbon nanotube (SWCNT) is a promising candidate for strengthening nanocomposite. As the matrix of nanocomposite, a single crystal of copper is designed to be in-plane auxetic along the crystal orientation [1 1 0]. In that way, the nanocomposite could also be auxetic when enhanced by (7, 2) a single-walled carbon nanotube with relatively small in-plane Poisson’s ratio. A series of molecular dynamics (MD) models of the nanocomposite metamaterial are then established to study mechanical behaviors of the nanocomposite. In the modelling, the gap between copper and SWCNT is determined following the principle of crystal stability. The enhanced effect for different content and temperature in different directions is discussed in detail. This study provides a complete set of mechanical parameters of nanocomposite including thermal expansion coefficients (TECs) from 300 K to 800 K for five weight fractions, which is essential for a wide range of applications of auxetic nanocompo...

- by Hui-Shen Shen
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- Nanomaterials

This study carried out finite element dynamic analyses of carbon nanotubes/fiber/polymer composites (CNTFPC) with various geometries. In the first application, the effects of CNTs on the nonlinear transient responses of doubly curved shells for various cutout sizes and curvatures are studied. The numerical results obtained are in good agreement with those reported by other investigators. For the practical application, the focus of this study is to evaluate various performances of concrete structures reinforced with a rebar-type CNTFPC. The new results reported in this article show the interactions between CNT weight ratios and crack sizes in CNTFPC-reinforced concrete structures. Key observation points are discussed and a brief design guideline is given.

- by Ashish Maharjan
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- Materials Science, Finite element method, Carbon Nanotube, Composite Material