scholarly journals The Buckling and Post-Buckling of Steel C-Columns in Elevated Temperature

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 74 ◽  
Author(s):  
Leszek Czechowski ◽  
Sławomir Kędziora ◽  
Zbigniew Kołakowski
Keyword(s):  
Experimental Studies ◽  
Large Strains ◽  
The Finite Element Method ◽  
Steel Columns ◽  
A Value ◽  
Load Carrying ◽  
Initial Load ◽  
Digital Correlation ◽  
Post Buckling ◽  
Thin Walled

This work deals with the investigation of a steel thin-walled C-column subjected to compression due to temperature increase. These experimental studies of the compressed columns in post-buckling state were conducted to determine their load-carrying capacity. To ensure appropriate supports and keeping of columns, plates with grooves were constructed. The tests of the columns’ compression for different preloads were carried out. By comparing the experiment results, numerical calculations based on the finite element method (FEM) and the semi-analytical method (SAM) of solution were performed. The computations were executed with the use of full material characteristics with consideration of large strains and deflections. Furthermore, while observing the deformation of columns, a non-contact Digital Correlation ARAMIS® system was employed whose calculated results of deformations are very close to the results of the numerical method. The paper revealed that maximum recorded loads under temperature rise are comparable regardless of a value of initial load. A good correlation in results between used methods was achieved. The main goal of the present work was to assess of behavior of thin-walled compressed steel columns in a temperature-controlled environment till their full damage.

scholarly journals Investigations on Torsion of the Two-Chords Single Laced Members

2017 ◽  
Vol 25 (2) ◽  
pp. 147-160
Author(s):  
Paweł Lorkowski ◽  
Bronisław Gosowski
Keyword(s):  
Cross Sections ◽  
Experimental Studies ◽  
The Finite Element Method ◽  
Second Moment ◽  
Steel Columns ◽  
Numerical Studies ◽  
Traction Network ◽  
Railway Traction ◽  
Parametric Analyses ◽  
The Relationship

Abstract The paper presents experimental and numerical studies to determine the equivalent second moment of area of the uniform torsion of the two-chord steel single laced members. The members are used as poles of railway traction network gates, and steel columns of framed buildings as well. The stiffness of uniform torsion of this kind of columns allows to the determine the critical loads of the spatial stability. The experimental studies have been realized on a single - span members with rotation arrested at their ends, loaded by a torque applied at the mid-span. The relationship between angle of rotation of the considered cross-section and the torque has been determined. Appropriate numerical model was created in the ABAQUS program, based on the finite element method. A very good compatibility has been observed between experimental and numerical studies. The equivalent second moment of area of the uniform torsion for analysed members has been determined by comparing the experimental and analytical results to those obtained from differential equation of non-uniform torsion, based on Vlasov’s theory. Additionally, the parametric analyses of similar members subjected to the uniform torsion, for the richer range of cross-sections have been carried out by the means of SOFiSTiK program. The purpose of the latter was determining parametrical formulas for calculation of the second moment of area of uniform torsion.

scholarly journals Catastrophic Influence of Global Distortional Modes on the Post-Buckling Behavior of Opened Columns

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3314
Author(s):  
Andrzej Teter ◽  
Zbigniew Kolakowski
Keyword(s):  
Cross Sections ◽  
Carrying Capacity ◽  
Strong Interactions ◽  
Load Carrying Capacity ◽  
Buckling Modes ◽  
Flexural Buckling ◽  
Load Carrying ◽  
Post Buckling ◽  
Global Modes ◽  
Thin Walled

The multimodal buckling of thin-walled isotropic columns with open cross-sections under uniform compression is discussed. Column lengths were selected to enable strong interactions between selected eigenmodes. In the case of short columns or very long ones subjected to compression, single-mode buckling can be observed only and the effect under discussion does not occur. In the present study, the influence of higher global modes on the load-carrying capacity and behavior in the post-buckling state of thin-walled structures with open cross-sections is analyzed in detail. In the literature known to the authors, higher global modes are always neglected practically in the analysis due to their very high values of bifurcation loads. However, the phenomenon of an unexpected loss in the load-carrying capacity of opened columns can be observed in the experimental investigations. It might be explained using multimode buckling when the higher global distortional-flexural buckling modes are taken into account. In the conducted numerical simulations, a significant influence of higher global distortional-flexural buckling modes on the post-buckling equilibrium path of uniformly compressed columns with C- and TH-shaped (the so-called “top-hat”) cross-sections was observed. The columns of two lengths, for which strong interactions between selected eigenmodes were seen, were subject to consideration. Two numerical methods were applied, namely, the semi-analytical method (SAM) using Koiter’s perturbation approach and the finite element method (FEM), to solve the problem. The SAM results showed that the third mode had a considerable impact on the load-carrying capacity, whereas the FEM results confirmed a catastrophic effect of the modes on the behavior of the structures under analysis, which led to a lack of convergence of numerical calculations despite an application of the Riks algorithm. All elastic-plastic effects were neglected.

scholarly journals Non-linear finite element analysis of the dynamics of a slender cable stayed tower

2018 ◽  
Vol 148 ◽  
pp. 03001
Author(s):  
Eliot Pezo ◽  
Paulo Gonçalves ◽  
Deane Roehl
Keyword(s):  
Finite Element ◽  
Structural Model ◽  
Design Stage ◽  
Nonlinear Behaviour ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Highly Nonlinear ◽  
Load Carrying ◽  
Post Buckling ◽  
Interactive Buckling

The aim of the present work is to investigate the static and dynamic nonlinear behaviour of a cable-stayed tower. A continuous structural model of a slender tower is discretized by the finite element method. First the buckling and post-buckling behaviour of the tower under axial load is explored, in order to understand the influence of the cable stiffness and lateral restrain on the load carrying capacity of the tower. Then, the linear vibration modes and frequencies are obtained. Due to the inherent symmetries of the tower, coincident buckling loads and vibration frequencies are obtained. This may lead to interactive buckling and internal resonance, increasing the effect of the geometric nonlinearities on the response. The results show that the tower exhibits a highly nonlinear response, which must be considered with care in the design stage.

Post-buckling inelastic analysis of thin-walled metal members using the Generalised Beam Theory

2019 ◽  
Author(s):  
Miguel Abambres ◽  
Dinar Camotim ◽  
Miguel Abambres
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Beam Theory ◽  
Flow Theory ◽  
Promising Alternative ◽  
Inelastic Analysis ◽  
Post Buckling ◽  
Thin Walled ◽  
Shell Finite Element ◽  
Generalised Beam Theory

A 2nd order inelastic Generalised Beam Theory (GBT) formulation based on the J2 flow theory is proposed, being a promising alternative to the shell finite element method. Its application is illustrated for an I-section beam and a lipped-C column. GBT results were validated against ABAQUS, namely concerning equilibrium paths, deformed configurations, and displacement profiles. It was concluded that the GBT modal nature allows (i) precise results with only 22% of the number of dof required in ABAQUS, as well as (ii) the understanding (by means of modal participation diagrams) of the behavioral mechanics in any elastoplastic stage of member deformation .

scholarly journals Eigenproblem Versus the Load-Carrying Capacity of Hybrid Thin-Walled Columns with Open Cross-Sections in the Elastic Range

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3468
Author(s):  
Zbigniew Kolakowski ◽  
Andrzej Teter
Keyword(s):  
Cross Sections ◽  
Carrying Capacity ◽  
Ultimate Load ◽  
Equilibrium Path ◽  
Load Carrying Capacity ◽  
Nonlinear Buckling ◽  
Elastic Range ◽  
Load Carrying ◽  
Thin Walled ◽  
Ultimate Load Carrying Capacity

The phenomena that occur during compression of hybrid thin-walled columns with open cross-sections in the elastic range are discussed. Nonlinear buckling problems were solved within Koiter’s approximation theory. A multimodal approach was assumed to investigate an effect of symmetrical and anti-symmetrical buckling modes on the ultimate load-carrying capacity. Detailed simulations were carried out for freely supported columns with a C-section and a top-hat type section of medium lengths. The columns under analysis were made of two layers of isotropic materials characterized by various mechanical properties. The results attained were verified with the finite element method (FEM). The boundary conditions applied in the FEM allowed us to confirm the eigensolutions obtained within Koiter’s theory with very high accuracy. Nonlinear solutions comply within these two approaches for low and medium overloads. To trace the correctness of the solutions, the Riks algorithm, which allows for investigating unsteady paths, was used in the FEM. The results for the ultimate load-carrying capacity obtained within the FEM are higher than those attained with Koiter’s approximation method, but the leap takes place on the identical equilibrium path as the one determined from Koiter’s theory.

scholarly journals Manufacturing, Characterisation and Mechanical Analysis of Polyacrylonitrile Membranes

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2378
Author(s):  
Mertol Tüfekci ◽  
Sevgi Güneş Durak ◽  
İnci Pir ◽  
Türkan Ormancı Acar ◽  
Güler Türkoğlu Demirkol ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Main Idea ◽  
Mechanical Analysis ◽  
Operating Conditions ◽  
Load Carrying Capacity ◽  
The Finite Element Method ◽  
Load Carrying ◽  
The Impact ◽  
Static Behaviour ◽  
Modelling Process

To investigate the effect of polyvinylpyrrolidone (PVP) addition and consequently porosity, two different sets of membranes are manufactured, since PVP is a widely used poring agent which has an impact on the mechanical properties of the membrane material. The first set (PAN 1) includes polyacrylonitrile (PAN) and the necessary solvent while the second set (PAN 2) is made of PAN and PVP. These membranes are put through several characterisation processes including tensile testing. The obtained data are used to model the static behaviour of the membranes with different geometries but similar loading and boundary conditions that represent their operating conditions. This modelling process is undertaken by using the finite element method. The main idea is to investigate how geometry affects the load-carrying capacity of the membranes. Alongside membrane modelling, their materials are modelled with representative elements with hexagonal and rectangular pore arrays (RE) to understand the impact of porosity on the mechanical properties. Exploring the results, the best geometry is found as the elliptic membrane with the aspect ratio 4 and the better RE as the hexagonal array which can predict the elastic properties with an approximate error of 12%.

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