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1 – 10 of 216Athanasios Bouboulas and Nikolaos Anifantis
– The purpose of this paper is to investigate the effect of crack surfaces contact on the post-buckling behavior of a slender column with a non-propagating crack.
Abstract
Purpose
The purpose of this paper is to investigate the effect of crack surfaces contact on the post-buckling behavior of a slender column with a non-propagating crack.
Design/methodology/approach
In this paper a 3D finite element model has been implemented to study the post-buckling behavior of a slender column with a non-propagating crack. According to this model, the column is discretized into three-dimensional solid elements. Contact conditions are considered between the crack surfaces. The non-linear equations for this model are solved using an incremental-iterative procedure, and the equilibrium path of the cracked column is extracted.
Findings
Load-displacement curves are presented for a cantilever column with a transverse surface crack of either uniform or non-uniform depth across the column cross-section. For both crack shapes, the load-displacement curves are presented for various values of crack depth and position. The results of this study are in good agreement with the results available in the literature. Comparisons with the results of the always-open crack were performed. The post-buckling behavior of a column with a uniform depth crack is more sensitive to variations in crack depth and position than the post-buckling behavior of a column with a non-uniform depth crack.
Originality/value
A 3D finite element approach for the post-buckling behavior of a transversely cracked column including contact between crack surfaces.
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Kaveh Salmalian, Ali Alijani and Habib Ramezannejad Azarboni
The purpose of this study is to investigate the post-buckling analysis of functionally graded columns by using three analytical, approximate and numerical methods. A pre-defined…
Abstract
Purpose
The purpose of this study is to investigate the post-buckling analysis of functionally graded columns by using three analytical, approximate and numerical methods. A pre-defined function as an initial assumption for the post-buckling path is introduced to solve the differential equation. The finite difference method is used to approximate the lateral deflection of the column based on the differential equation. Moreover, the finite element method is used to derive the tangent stiffness matrix of the column.
Design/methodology/approach
The non-linear buckling analysis of functionally graded materials is carried out by using three analytical, finite difference and finite element methods. The elastic deformation and Euler-Bernoulli beam theory are considered to establish the constitutive and kinematics relations, respectively. The governing differential equation of the post-buckling problem is derived through the energy method and the calculus variation.
Findings
An incremental iterative solution and the perturbation of the displacement vector at the critical buckling point are performed to determine the post-buckling path. The convergence of the finite element results and the effects of geometric and material characteristics on the post-buckling path are investigated.
Originality/value
The key point of the research is to compare three methods and to detect error sources by considering the derivation process of relations. This comparison shows that a non-incremental solution in the analytical and finite difference methods and an initial assumption in the analytical method lead to an error in results. However, the post-buckling path in the finite element method is traced by the updated tangent stiffness matrix in each load step without any initial limitation.
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S.A.M. Ghannadpour and H.R. Ovesy
The purpose of this paper is to develop and apply an exact finite strip (F‐a FSM) for the buckling and initial post‐buckling analyses of box section struts.
Abstract
Purpose
The purpose of this paper is to develop and apply an exact finite strip (F‐a FSM) for the buckling and initial post‐buckling analyses of box section struts.
Design/methodology/approach
The Von‐Karman's equilibrium equation is solved exactly to obtain the buckling loads and deflection modes for the struts. The investigation is then extended to an initial post‐buckling study with the assumption that the deflected form immediately after the buckling is the same as that obtained for the buckling. Through the solution of the Von‐Karman's compatibility equation, the in‐plane displacement functions are developed in terms of the unknown coefficient. These in‐plane and out‐of‐plane deflected functions are then substituted in the total strain energy expressions and the theorem of minimum total potential energy is applied to solve for the unknown coefficient.
Findings
The F‐a FSM is applied to analyze the buckling and initial post‐buckling behavior of some representative box sections for which the results were also obtained through the application of a semi‐energy finite strip method (S‐e FSM). For a given degree of accuracy in the results, however, the F‐a FSM analysis requires less computational effort.
Research limitations/implications
In the present F‐a FSM, only one of the calculated deflection modes is used for the initial post‐buckling study.
Practical implications
A very useful and computationally economical methodology is developed for the initial design of struts which encounter post‐buckling.
Originality/value
The originality of the paper is the fact that by incorporating a rigorous buckling solution into the Von‐Karman's compatibility equation, and solving it, a fairly efficient method for post‐buckling stiffness calculation is achieved.
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Djamel Boutagouga and Said Mamouri
This paper aims to investigate post-buckling responses of shell-like structures using an implicit conservative-decaying time integration dynamic scheme.
Abstract
Purpose
This paper aims to investigate post-buckling responses of shell-like structures using an implicit conservative-decaying time integration dynamic scheme.
Design/methodology/approach
In this work, the authors have proposed the use of a four-node quadrilateral flat shell finite element with drilling rotational degree of freedom within the framework of an updated Lagrangian formulation mutually with an implicit conservative-dissipative time integration dynamic scheme.
Findings
Several numerical simulations were considered to evaluate the accuracy, robustness, stability and the capacity of the considered time integration scheme to dissipate numerical noise in the presence of high frequencies. The obtained results illustrate a very satisfying performance of the implicit conservative-dissipative direct time integration scheme conjointly with the quadrilateral flat shell finite element with drilling rotation.
Originality/value
The authors have investigated the potential of the implicit dynamic scheme to deal with unstable branches after limit points in the non-linear post-buckling response of shell structures with no need for structural damping. The capability of the studied algorithm to study buckling and post-buckling behaviour of thin shell structures is illustrated through several numerical examples.
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Haiyang Hu, Yu Wang, Chenchen Lian and Peiyan Wang
In this paper, an attempt is made to obtain buckling loads, ultimate bearing capacity and other required structural characteristics of grid structure panels. The numerical method…
Abstract
Purpose
In this paper, an attempt is made to obtain buckling loads, ultimate bearing capacity and other required structural characteristics of grid structure panels. The numerical method for post-buckling behavior analysis of panels involving multiple invisible damages is also presented.
Design/methodology/approach
In this paper, two bidirectional stiffened composite panels are manufactured and tested. Multiple discrete invisible damages are introduced in different positions of the stringers, and the experimental and simulation investigation of buckling and post-buckling were carried out on the damaged stiffened panels.
Findings
The simulation load–displacement curves are compared with the experimental results, and it is found that the simulation model can well predict the occurrence of buckling and failure loads. The strain curve shows that the rate of strain change at the damaged site is greater than that at the undamaged site, which reflects that the debond is more likely occurred at the damaged site. The simulation verifies that the panel is usually crushed due to matrix compression and fiber–matrix shear.
Originality/value
In this paper, post-buckling tests and numerical simulations of bidirectional stiffened composite panels with impact damage were carried out. Two panels with four longitudinal stringers and two transverse stringers were manufactured and tested. The buckling and post-buckling characteristics of the grid structure are obtained, and the failure mechanism of the structure is explained. This is helpful for the design of wall panel structure.
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Alexandre Landesmann and Dinar Camotim
This paper reports the available results of an ongoing shell finite element investigation on the distortional buckling, post-buckling and ultimate strength behaviour of…
Abstract
This paper reports the available results of an ongoing shell finite element investigation on the distortional buckling, post-buckling and ultimate strength behaviour of cold-formed steel lipped channel columns (centrally compressed members) subjected to high temperatures typically caused by fire conditions. Two column collapse situations are dealt with, corresponding to different loading strategies: (i) application of an increasing compressive load to columns subjected to a constant (uniform) temperature distribution, in order to obtain failure loads, and (ii) application of a progressive temperature raise to axially compressed column, in order to obtain failure temperatures - the latter approach provides a more realistic simulation of fire conditions. The steel material behaviour at high temperatures is described by the constitutive model prescribed in Eurocode 3 for cold-formed steel. After validating the numerical model adopted, through the comparison with results of simulations reported in the literature and based on experimentally obtained stress-strain laws, the paper presents numerical results concerning lipped channel columns made of various steel grades under fire conditions - they consist of (i) non-linear equilibrium paths, yielded by steady state and transient column analyses, and (ii) the corresponding failure loads/stresses and temperatures.
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Efstathios E. Theotokoglou, Georgios Balokas and Evgenia K. Savvaki
The purpose of this paper is to investigate the buckling behavior of the load-carrying support structure of a wind turbine blade.
Abstract
Purpose
The purpose of this paper is to investigate the buckling behavior of the load-carrying support structure of a wind turbine blade.
Design/methodology/approach
Experimental experience has shown that local buckling is a major failure mode that dominantly influences the total collapse of the blade.
Findings
The results from parametric analyses offer a clear perspective about the buckling capacity but also about the post-buckling behavior and strength of the models.
Research limitations/implications
This makes possible to compare the response of the different fiber-reinforced polymers used in the computational model.
Originality/value
Furthermore, this investigation leads to useful conclusions for the material design optimization of the load-carrying box girder, as significant advantages derive not only from the combination of different fiber-reinforced polymers in hybrid material structures, but also from Kevlar-fiber blades.
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Fábio Ribeiro Soares da Cunha, Tobias Wille, Richard Degenhardt, Michael Sinapius, Francisco Célio de Araújo and Rolf Zimmermann
– The purpose of this paper is to present the probabilistic approach to a new robustness-based design strategy for thin-walled composite structures in post-buckling.
Abstract
Purpose
The purpose of this paper is to present the probabilistic approach to a new robustness-based design strategy for thin-walled composite structures in post-buckling.
Design/methodology/approach
Because inherent uncertainties in geometry, material properties, ply orientation and thickness affect the structural performance and robustness, these variations are taken into account.
Findings
The methodology is demonstrated for the sake of simplicity with an unstiffened composite plate under compressive loading, and the probabilistic and deterministic results are compared. In this context, the structural energy and uncertainties are employed to investigate the robustness and reliability of thin-walled composite structures in post-buckling.
Practical implications
As practical implication, the methodology can be extended to stiffened shells, widely used in aerospace design with the aim to satisfy weight, strength and robustness requirements. Moreover, a new argument is strengthened to accept the collapse close to ultimate load once robustness is ensured with a required reliability.
Originality/value
This innovative strategy embedded in a probabilistic framework might lead to a different design selection when compared to a deterministic approach, or an approach that only accounts for the ultimate load. Moreover, robustness measures are redefined in the context of a probabilistic design.
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Gives a bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the…
Abstract
Gives a bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the theoretical as well as practical points of view. The range of applications of FEMs in this area is wide and cannot be presented in a single paper; therefore aims to give the reader an encyclopaedic view on the subject. The bibliography at the end of the paper contains 2,025 references to papers, conference proceedings and theses/dissertations dealing with the analysis of beams, columns, rods, bars, cables, discs, blades, shafts, membranes, plates and shells that were published in 1992‐1995.
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Mostefa Mimoune, Saad Siouane and Fatima Mimoune
This paper develops a finite-element model using ANSYS for the buckling analysis of perforated beams and uses it to investigate the effects of slenderness on the moment-gradient…
Abstract
This paper develops a finite-element model using ANSYS for the buckling analysis of perforated beams and uses it to investigate the effects of slenderness on the moment-gradient factor of simply supported perforated web beams. Web post buckling is studied by using numerical model. An investigation on steel beams with various shapes and sizes is reported based on web post buckling. A parameter study was conducted based on web post width and the effect of various openings is described.
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