• Title, Summary, Keyword: post-buckling

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Post-buckling analysis of aorta artery under axial compression loads

  • Akbas, Seref Doguscan;Mercan, Kadir;Civalek, Omer
    • Advances in nano research
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    • v.8 no.3
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    • pp.255-264
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    • 2020
  • Buckling and post-buckling cases are often occurred in aorta artery because it affected by higher pressure. Also, its stability has a vital importance to humans and animals. The loss of stability in arteries may lead to arterial tortuosity and kinking. In this paper, post-buckling analysis of aorta artery is investigated under axial compression loads on the basis of Euler-Bernoulli beam theory by using finite element method. It is known that post-buckling problems are geometrically nonlinear problems. In the geometrically nonlinear model, the Von Karman nonlinear kinematic relationship is employed. Two types of support conditions for the aorta artery are considered. The considered non-linear problem is solved by using incremental displacement-based finite element method in conjunction with Newton-Raphson iteration method. The aorta artery is modeled as a cylindrical tube with different average diameters. In the numerical results, the effects of the geometry parameters of aorta artery on the post-buckling case are investigated in detail. Nonlinear deflections and critical buckling loads are obtained and discussed on the post-buckling case.

Large post-buckling behavior of Timoshenko beams under axial compression loads

  • Akbas, Seref D.
    • Structural Engineering and Mechanics
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    • v.51 no.6
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    • pp.955-971
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    • 2014
  • Large post-buckling behavior of Timoshenko beams subjected to non-follower axial compression loads are studied in this paper by using the total Lagrangian Timoshenko beam element approximation. Two types of support conditions for the beams are considered. In the case of beams subjected to compression loads, load rise causes compressible forces end therefore buckling and post-buckling phenomena occurs. It is known that post-buckling problems are geometrically nonlinear problems. The considered highly non-linear problem is solved considering full geometric non-linearity by using incremental displacement-based finite element method in conjunction with Newton-Raphson iteration method. There is no restriction on the magnitudes of deflections and rotations in contradistinction to von-Karman strain displacement relations of the beam. The beams considered in numerical examples are made of lower-Carbon Steel. In the study, the relationships between deflections, rotational angles, critical buckling loads, post-buckling configuration, Cauchy stress of the beams and load rising are illustrated in detail in post-buckling case.

Thermal post-buckling analysis of a laminated composite beam

  • Akbas, Seref D.
    • Structural Engineering and Mechanics
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    • v.67 no.4
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    • pp.337-346
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    • 2018
  • The purpose of this study is to investigate thermal post-buckling analysis of a laminated composite beam subjected under uniform temperature rising with temperature dependent physical properties. The beam is pinned at both ends and immovable ends. Under temperature rising, thermal buckling and post-buckling phenomena occurs with immovable ends of the beam. In the nonlinear kinematic model of the post-buckling problem, total Lagrangian approach is used in conjunction with the Timoshenko beam theory. Also, material properties of the laminated composite beam are temperature dependent: that is the coefficients of the governing equations are not constant. In the solution of the nonlinear problem, incremental displacement-based finite element method is used with Newton-Raphson iteration method. The effects of the fibber orientation angles, the stacking sequence of laminates and temperature rising on the post-buckling deflections, configurations and critical buckling temperatures of the composite laminated beam are illustrated and discussed in the numerical results. Also, the differences between temperature dependent and independent physical properties are investigated for post-buckling responses of laminated composite beams.

Post-buckling analysis of Timoshenko beams with temperature-dependent physical properties under uniform thermal loading

  • Akbas, Seref Doguscan;Kocaturk, Turgut
    • Structural Engineering and Mechanics
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    • v.44 no.1
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    • pp.109-125
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    • 2012
  • Post-buckling behavior of Timoshenko beams subjected to uniform temperature rising with temperature dependent physical properties are studied in this paper by using the total Lagrangian Timoshenko beam element approximation. The beam is clamped at both ends. In the case of beams with immovable ends, temperature rise causes compressible forces end therefore buckling and post-buckling phenomena occurs. It is known that post-buckling problems are geometrically nonlinear problems. Also, the material properties (Young's modulus, coefficient of thermal expansion, yield stress) are temperature dependent: That is the coefficients of the governing equations are not constant in this study. This situation suggests the physical nonlinearity of the problem. Hence, the considered problem is both geometrically and physically nonlinear. The considered highly non-linear problem is solved considering full geometric non-linearity by using incremental displacement-based finite element method in conjunction with Newton-Raphson iteration method. The beams considered in numerical examples are made of Austenitic Stainless Steel (316). The convergence studies are made. In this study, the difference between temperature dependent and independent physical properties are investigated in detail in post-buckling case. The relationships between deflections, thermal post-buckling configuration, critical buckling temperature, maximum stresses of the beams and temperature rising are illustrated in detail in post-buckling case.

Buckling of post-tensioned composite beams

  • Bradford, M.A.
    • Structural Engineering and Mechanics
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    • v.2 no.1
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    • pp.113-123
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    • 1994
  • A method for computing the elastic buckling prestressing force of a post-tensioned composite steel-concrete tee-beam is presented. The method is based on a virtual work formulation, and incorporates the restraint provided by the concrete slab to the buckling displacements of the steel beam. The distortional buckling solutions are shown to be given by a quadratic equation. The application of the analysis to calculation buckling strengths is given, based on codified rules for beam-columns. Conclusions are then drawn on the importance of distortional buckling when a post-tensioned composite beam is stressed during jacking.

Post-buckling analysis of Mindlin Cut out-plate reinforced by FG-CNTs

  • Motezaker, Mohsen;Eyvazian, Arameh
    • Steel and Composite Structures
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    • v.34 no.2
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    • pp.289-297
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    • 2020
  • In the present research post-buckling of a cut out plate reinforced through carbon nanotubes (CNTs) resting on an elastic foundation is studied. Material characteristics of CNTs are hypothesized to be altered within thickness orientation which are calculated according to Mori-Tanaka model. For modeling the system mathematically, first order shear deformation theory (FSDT) is applied and using energy procedure, the governing equations can be derived. With respect to Rayleigh-Ritz procedure as well as Newton-Raphson iterative scheme, the motion equations are solved and therefore, post-buckling behavior of structure will be tracked. Diverse parameters as well as their reactions on post-buckling paths focusing cut out measurement, CNT's volume fraction and agglomeration, dimension of plate and an elastic foundation are investigated. It is revealed that presence of a square cut out can affect negatively post-buckling behavior of structure. Moreover, adding nanocompsits in the matrix leads to enhancement of post-buckling response of system.

Simplified method for prediction of elastic-plastic buckling strength of web-post panels in castellated steel beams

  • Liu, Mei;Guo, Kangrui;Wang, Peijun;Lou, Chao;Zhang, Yue
    • Steel and Composite Structures
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    • v.25 no.6
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    • pp.671-684
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    • 2017
  • Elastic-plastic shear buckling behaviors of the web-post in a Castellated Steel Beam (CSB) with hexagonal web openings under vertical shear force were investigated further using Finite Element Model (FEM) based on a sub-model, which took the upper part of the web-post under horizontal shear force to represent the whole web-post under vertical shear force. A simplified design method for the web-post elastic-plastic shear buckling strength was proposed based on simulation results of the sub-model. Proper boundary conditions were applied to the sub-model to assure that its behaviors were identical to those of the whole web-post. The equation to calculate the thin plate elastic shear buckling strength was adopted as the basic form to build the design equation for elastic-plastic buckling strength of the sub-model. Parameters that might affect the elastic-plastic shear buckling strength of the whole web-post were studied. After obtaining the vertical shear buckling strength of a sub-model through FEM, the shear buckling coefficient k can be obtained through the back analysis. A practical calculation method for k was proposed through curving fitting the parameter study results. The elastic-plastic shear buckling strength of the web-post calculated using the proposed shear buckling coefficient k agreed well with that obtained from the FEM and test results. And it was more precise than those obtained from EC3 based on the strut model.

The Evaluation of the Previous Models Used to Study the Web Post-buckling

  • Mai, Thi-Hang;Han, Sang-Yun;Kim, Dae-Hyeak;Kang, Young-Jong
    • International journal of steel structures
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    • v.17 no.3
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    • pp.1131-1143
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    • 2017
  • The number of suggested and modified theories for web post-buckling behavior shows that this is one of the topics receiving much attention in civil engineering. However, the controversy related to the elusive behavior of web post-buckling is going on. The present study using an updated data set from 27 previous experimental shear tests and the current FEA results is to evaluate Basler's model which represents classical theories and Lee and Yoo's model which represents recent researches. This research indicates that none of the investigated models provides the accurate prediction of ultimate shear strength in the whole range of practical parameters, they tend to overestimate or underestimate the ultimate shear strength of the girder depending on the aspect ratio of the web panel. Besides, the current FEA results reveal that the in-plane tension field (classical tension field) as in Basler's theory is not the unique source in web post-buckling reserve and does not characterize the actual behavior of web post-buckling. The reason is that the stresses on two surfaces of the web panel dominate the post-buckling reserve.

Optimum Shape for Buckling and Post-Buckling Behavior of a Laminated Composite Panel with I-type Stiffeners

  • Lee, Gwang-Rog;Yang, Won-Ho;Sub, Myung-Won
    • Journal of Mechanical Science and Technology
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    • v.16 no.10
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    • pp.1211-1221
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    • 2002
  • A shape optimization of stiffener was conducted to increase buckling load or failure load with stiffened laminated composite panel of I-type under compression loading. Design variables are cap length, web length, and/or thickness under the constraint of volume constancy. The objective function is buckling load and failure load of post-buckling based on Tsai-Hill theory using ABAQUS 5.8 for analysis and Optimizer on Broydon-Fletcher Goldfarb-Sharno Method and Augmented Lagrange Multiplier Method. The effects of relative length of a web and a cap of stiffener on buckling load and failure load of post-buckling were investigated with the results of optimum design.

Inelastic buckling and post-buckling behavior of gusset plate connections

  • Hadianfard, Mohammad Ali;Khakzad, Ali Reza
    • Steel and Composite Structures
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    • v.22 no.2
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    • pp.411-427
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    • 2016
  • In this study, by using finite element non-linear static analysis and comparing it with experimental models, the buckling and post-buckling behavior of bracing gusset plates has been investigated. The effects of such parameters as dimension and thickness of the gusset plate and the influence of position of the bracing member on the behavior of gusset plate have been examined. The results of the analyses clearly suggest that capacity, buckling and post-buckling behaviors of gusset plates depend on the position of the bracing splice plate with respect to the free bending line as well as on the size and thickness of the gusset plate. Also, with respect to numerical analysis results, some practical graphs for the calculation of buckling capacity of gusset plate connections are presented. For steel structures, the proposed method is apparently more accurate than available code procedures.