Designing Hierarchical IsoTruss Column Based on Controlling Multi-Buckling Behaviors

2021 ◽  
Author(s):  
Changliang Lai ◽  
Qianqian Sui ◽  
Hualin Fan
Keyword(s):  
Finite Element ◽  
Parametric Design ◽  
Local Buckling ◽  
Fe Model ◽  
The Finite Element Method ◽  
Buckling Modes ◽  
Buckling Behavior ◽  
Global Buckling ◽  
Buckling Failure ◽  
Theoretical Analyses

To develop large-span but ultralight lattice truss columns, a hierarchical IsoTruss column (HITC) was proposed. The multi-buckling behavior of the axially compressed HITC was analyzed by the finite element method (FEM) using a parametric approach in the framework of ANSYS parametric design language (APDL). It was demonstrated that the program enables efficient generation of the finite element (FE) model, while facilitating the parametric design of the HITC. Using this program, the effects of helical angles and brace angles on the buckling behavior of the HITC were investigated. Depending on the helical angles and brace angles, the HITCs mainly have three buckling modes: the global buckling, the first-order local buckling and the second-order local buckling. Theoretical multi-buckling models were established to predict the critical buckling loads. Buckling failure maps based on the theoretical analyses were also developed, which can be useful in preliminary design of such structures.

scholarly journals Numerical Simulation of Multi-Span Greenhouse Structures

Agriculture ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 499
Author(s):  
María S. Fernández-García ◽  
Pablo Vidal-López ◽  
Desirée Rodríguez-Robles ◽  
José R. Villar-García ◽  
Rafael Agujetas
Keyword(s):  
Matrix Method ◽  
Local Buckling ◽  
External Pressure ◽  
Climatic Conditions ◽  
Wind Loads ◽  
Buckling Modes ◽  
First Order ◽  
Global Buckling ◽  
Computational Fluid Dynamics Cfd ◽  
Buckling Failure

Greenhouses had to be designed to sustain permanent maintenance and crop loads as well as the site-specific climatic conditions, with wind being the most damaging. However, both the structure and foundation are regularly empirically calculated, which could lead to structural inadequacies or cost ineffectiveness. Thus, in this paper, the structural assessment of a multi-tunnel greenhouse was carried out. Firstly, wind loads were assessed through computational fluid dynamics (CFD). Then, the buckling failure mode when either the European Standard (EN) or the CFD wind loads were contemplated was assessed by a finite element method (FEM). Conversely to the EN 13031-1, CFD wind loads generated a suction in the 0–55° region of the first tunnel and a 60% reduction of the external pressure coefficients in the third tunnel was not detected. Moreover, the first-order buckling eigenvalues were reduced (32–57%), which resulted in the need for a different calculation method (i.e., elastoplastic analysis), and global buckling modes similar to local buckling shape were detected. Finally, the foundation was studied by the FEM and a matrix method based on the Wrinkler model. The stresses and deformations arising from the proposed matrix method were conservative compared to those obtained by the FEM.

Effect of Implanted Delamination and Core Density on the Buckling Behavior of Sandwich Composites

2000 ◽  
Author(s):  
Hassan Mahfuz ◽  
Syful Islam ◽  
Leif Carlsson ◽  
Makeba Atkins ◽  
Shaik Jeelani
Keyword(s):  
Finite Element ◽  
Local Buckling ◽  
Sandwich Composites ◽  
Core Density ◽  
Sandwich Construction ◽  
Buckling Behavior ◽  
The Face ◽  
Global Buckling ◽  
Plane Compression ◽  
Overall Buckling

Abstract Foam core sandwich composites have been fabricated using innovative co-injection resin infusion technique and tested under in-plane compression. The sandwich construction consisted of Klegcell foam as core materials and S2-Glass/Vinyl ester composites as face sheets. Tests were conducted with various foam densities and also with implanted delamination between the core and the face sheet. The intent was to investigate the effect of core density, and the effect of core-skin debonds on the overall buckling behavior of the sandwich. Analytical and finite element calculations were also performed to augment the experimental observations. It has been observed that core density has direct influence on the global buckling of the sandwich panel, while embedded delamination seem to have minimal effect on both global as well as local buckling. Detailed description of the experimental work, finite element modeling and analytical calculations are presented in this paper.

Numerical Analysis of Debonded Honeycomb Sandwich Structure under Compressive Load

2013 ◽  
Vol 658 ◽  
pp. 227-231
Author(s):  
Tao Zhu ◽  
Jin Long Chen ◽  
Wen Ran Gong
Keyword(s):  
Finite Element ◽  
Local Buckling ◽  
Compressive Load ◽  
Sandwich Panels ◽  
Element Model ◽  
Damage Propagation ◽  
Buckling Behavior ◽  
Honeycomb Sandwich ◽  
Global Buckling ◽  
Honeycomb Sandwich Structure

In this paper, the finite element method (FEM) was applied to predict the local buckling behavior and the debond propagation in honeycomb sandwich panels with face-core debond under in-plane compressive load. The finite element model of the sandwich panel was built, the cohesive element was used to model the adhesive between faces and core, the influence of the debond shape and size on the failure mode, critical buckling load and residual compressive strength of the sandwich panels was investigated, the rule of the damage propagation was summarized. The compression strength of the sandwich panels with through-width face-core debond decreases with increasing debond length. For the panels with central circular debond, when the diameter is less than 15mm, the panels will failure by global buckling and the debond will not grow. When the diameter is greater than 15mm, the panels will failure by local buckling and the critical load strongly decreases with increasing debond diameter. In addition, the direction of debond growth is predominantly perpendicular to the applied load.

scholarly journals ESTUDO NUMÉRICO DA FLAMBAGEM LOCAL NA MESA EM PERFIS DE ALMA SENOIDAL SUBMETIDOS À COMPRESSÃO AXIAL [Numerical Study of the Flange Local Buckling in Sinusoidal Web Profiles under Compressive Strength]

2018 ◽  
Vol 14 (2) ◽  
Author(s):  
Melina Guimarães Alves ◽  
Francisco Carlos Rodrigues ◽  
Ricardo Hallal Fakury ◽  
Ana Lydia Reis de Castro e Silva
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Compressive Strength ◽  
Numerical Study ◽  
Local Buckling ◽  
Numerical Results ◽  
Relative Performance ◽  
The Finite Element Method ◽  
Buckling Modes ◽  
Critical Tension

RESUMO: Este trabalho avaliou o desempenho relativo de perfis de alma senoidal quando comparados aos perfis de alma plana através do estudo numérico da flambagem local em mesas (FLM) de barras submetidas à compressão axial. Para a realização deste estudo foram discretizados dois modelos via Método dos Elementos Finitos (MEF) com o emprego do programa ABAQUS®. A metodologia numérica baseou-se em realizar análise de carga crítica de flambagem local, mantendo-se fixo os valores de largura de mesas, espessura e altura de alma para cada perfil e alterar gradativamente a espessura das mesas, sendo possível atingir vários resultados de tensão crítica para cada esbeltez, definindo-se a curva tensão versus esbeltez da fase elástica. A partir dos resultados numéricos obtidos foi possível realizar a parametrização analítica com as prescrições da norma ABNT NBR 8800:2008 e fazer uma proposição de metodologia de cálculo para os parâmetros de esbeltez das mesas. Posteriormente, realizaram-se comparativos entre o desempenho dos perfis de alma senoidal e o dos perfis de alma plana. Os resultados numéricos mostraram que o desempenho de um perfil de alma senoidal pode ser até 8% mais eficiente que o dos perfis de alma plana, no que tange a possibilidade de colapso do perfil sem a ocorrência de FLM quando submetidos à compressão axial.ABSTRACT: This work evaluated the relative performance of sinusoidal web profiles through the numerical study of flange local buckling (FLB) for simple bars under compressive strength, when compared to flat web profiles. For this study, two models were discretized using the Finite Element Method (FEM) through the ABAQUS® program. The numerical methodology was based on Buckle analysis, maintaining the values of table width, web thickness and web height for each profile and gradually changing the thickness of the flanges, this way was possible to reach several results of critical tension for each slenderness, being defined the curve of the elastic phase. From the numerical results obtained it was possible to perform the analytical parameterization with the norm ABNT NBR8800:2008 and to make a proposition of calculation for the parameters of slenderness that limit each buckling modes of the flanges. Considering these results, comparisons were made between the performance of the sinusoidal web profiles and those from the flat web profiles. The numerical results showed that the performance of a sinusoidal web profile can be up to 8% more efficient than flat soul profiles, regarding the possibility of collapse of the structure without the occurrence of FLB when subjected under compressive strength.

Critical Strain of Carbon Nanotubes: An Atomic-Scale Finite Element Study

2006 ◽  
Vol 74 (2) ◽  
pp. 347-351 ◽  
Author(s):  
X. Guo ◽  
A. Y. T. Leung ◽  
H. Jiang ◽  
X. Q. He ◽  
Y. Huang
Keyword(s):  
Carbon Nanotubes ◽  
Finite Element ◽  
Critical Strain ◽  
Local Buckling ◽  
Atomic Scale ◽  
Energy Curve ◽  
Outer Diameter ◽  
Covalent Bonds ◽  
Buckling Behavior ◽  
Global Buckling

This paper employs the atomic-scale finite element method (AFEM) to study critical strain of axial buckling for carbon nanotubes (CNTs). Brenner et al. “second-generation” empirical potential is used to model covalent bonds among atoms. The computed energy curve and critical strain for (8, 0) single-walled CNT (SWNT) agree well with molecular dynamics simulations. Both local and global buckling are achieved, two corresponding buckling zones are obtained, and the global buckling behavior of SWNT with a larger aspect ratio approaches gradually to that of a column described by Euler’s formula. For double-walled CNTs with smaller ratio of length to outer diameter, the local buckling behavior can be explained by conventional shell theory very well. AFEM is an efficient way to study buckling of CNTs.

Study on the Local Buckling Behavior of Steel Equal Angle Members under Axial Compression with the Steel Strength Variation

2011 ◽  
Vol 374-377 ◽  
pp. 2430-2436
Author(s):  
Gang Shi ◽  
Zhao Liu ◽  
Yong Zhang ◽  
Yong Jiu Shi ◽  
Yuan Qing Wang
Keyword(s):  
Finite Element ◽  
Axial Compression ◽  
High Strength Steel ◽  
Local Buckling ◽  
Steel Structures ◽  
High Strength ◽  
Element Analysis ◽  
Equal Angle ◽  
Buckling Behavior ◽  
Steel Strength

High strength steel sections have been increasingly used in buildings and bridges, and steel angles have also been widely used in many steel structures, especially in transmission towers and long span trusses. However, high strength steel exhibits mechanical properties that are quite different from ordinary strength steel, and hence, the local buckling behavior of steel equal angle members under axial compression varies with the steel strength. However, there is a lack of research on the relationship of the local buckling behavior of steel equal angle members under axial compression with the steel strength. A finite element model is developed in this paper to analyze the local buckling behavior of steel equal angle members under axial compression, and study its relationship with the steel strength and the width-to-thickness ratio of the angle leg. The finite element analysis (FEA) results are compared with the corresponding design method in the American code AISC 360-05, which provides a reference for the related design.

Collapse of Tubes Under Combined Bending and Axial Compression Loads

2018 ◽  
Author(s):  
Shan Jin ◽  
Shuai Yuan ◽  
Yong Bai
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Axial Compression ◽  
Local Buckling ◽  
Practical Application ◽  
Buckling Modes ◽  
Combined Loads ◽  
Bending Loads ◽  
Good Agreement

In practical application, pipelines will inevitably experience bending and compression during manufacture, transportation and offshore installation. The mechanical behavior of tubes under combined axial compression and bending loads is investigated using experiments and finite element method in this paper. Tubes with D/t ratios in the range of 40 and 97 are adopted in the experiments. Then, the ultimate loads and the local buckling modes of tubes are studied. The commercial software ABAQUS is used to build FE models to simulate the load-shortening responses of tubes under combined loads. The results acquired from the ABAQUS simulation are compared with the ones from verification bending experiment, which are in good agreement with each other. The models in this paper are feasible to analyze the mechanical properties of tubes under combined axial compression and bending loads. The related results may be of interest to the manufacture engineers.

Finite Element Simulation Analysis on Space KX-Joint

2014 ◽  
Vol 915-916 ◽  
pp. 146-149
Author(s):  
Yong Sheng Wang ◽  
Li Hua Wu
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Simulation Analysis ◽  
Local Buckling ◽  
Element Model ◽  
Ansys Software ◽  
Element Simulation ◽  
Calculation Results ◽  
Buckling Failure ◽  
The Finite Element Model

The finite element model of the space KX-Joint was established using ANSYS software, and the failure mode and ultimate bearing capacity of KX-joint were researched. Calculation results show that the surface of chord wall on the roots of compression web members was into the plastic in K plane, and the holding pole without the plastic area and the local buckling failure happened in the surface of chord wall on the roots of Compression Web Members in X plane; The bearing capacity of the joint increased with the Chord diameter, which was appears in the form of power function.

scholarly journals A robust 3D finite element model for concrete columns confined by FRCM system

2019 ◽  
Vol 281 ◽  
pp. 01006 ◽  
Author(s):  
Majid M.A. Kadhim ◽  
Mohammed J Altaee ◽  
Ali Hadi Adheem ◽  
Akram R. Jawdhari
Keyword(s):  
Finite Element ◽  
Cement Mortar ◽  
Three Dimensional ◽  
Concrete Columns ◽  
Element Model ◽  
Fe Model ◽  
3D Finite Element ◽  
Composite Failure ◽  
Global Buckling ◽  
Fibre Reinforced Polymer

Fibre reinforced cementitious matric (FRCM) is a recent application of fibre reinforced polymer (FRP) reinforcement, developed to overcome several limitations associated with the use of organic adhesive [e.g. epoxies] in FRPs. It consists of two dimensional FRP mesh saturated with a cement mortar, which is inorganic in nature and compatible with concrete and masonry substrates. In this study, a robust three-dimensional (3D) finite element (FE) model has been developed to study the behaviour of slender reinforced concrete columns confined by FRCM jackets, and loaded concentrically and eccentrically. The model accounts for material nonlinearities in column core and cement mortar, composite failure of FRP mesh, and global buckling. The model response was validated against several laboratory tests from literature, comparing the ultimate load, load-lateral deflection and failure mode. Maximum divergence between numerical and experimental results was 12%. Following the validation, the model will be used later in a comprehensive parametric analysis to gain a profound knowledge of the strengthening system, and examine the effects of several factors expected to influence the behaviour of confined member.

GBT FORMULATION TO ANALYZE THE BUCKLING BEHAVIOR OF THIN-WALLED MEMBERS SUBJECTED TO NON-UNIFORM BENDING

2007 ◽  
Vol 07 (01) ◽  
pp. 23-54 ◽  
Author(s):  
RUI BEBIANO ◽  
NUNO SILVESTRE ◽  
DINAR CAMOTIM
Keyword(s):  
Finite Element ◽  
Major Axis ◽  
Shear Stresses ◽  
Longitudinal Stress ◽  
Stress Gradients ◽  
Stiffness Reduction ◽  
Buckling Behavior ◽  
Global Buckling ◽  
Thin Walled ◽  
Uniformly Distributed Loads

In this paper, one investigates the local-plate, distortional and global buckling behavior of thin-walled steel beams subjected to non-uniform bending moment diagrams, i.e. under the presence of longitudinal stress gradients. One begins by deriving a novel formulation based on Generalized Beam Theory (GBT), which (i) can handle beams with arbitrary open cross-sections and (ii) incorporates all the effects stemming from the presence of longitudinally varying stress distributions. This formulation is numerically implemented by means of the finite element method: one (i) develops a GBT-based beam finite element, which accounts for the stiffness reduction associated to applied longitudinal stresses with linear, quadratic and cubic variation, as well as to the ensuing shear stresses, and (ii) addresses the derivation of the equilibrium equation system that needs to be solved in the context of a GBT buckling analysis. Then, in order to illustrate the application and capabilities of the proposed GBT-based formulation and finite element implementation, one presents and discusses numerical results concerning (i) rectangular plates under longitudinally varying stresses and pure shear, (ii) I-section cantilevers subjected to uniform major axis bending, tip point loads and uniformly distributed loads, and (iii) simply supported lipped channel beams subjected to uniform major axis bending, mid-span point loads and uniformly distributed loads — by taking full advantage of the GBT modal nature, one is able to acquire an in-depth understanding on the influence of the longitudinal stress gradients and shear stresses on the beam local and global buckling behavior. For validation purposes, the GBT results are compared with values either (i) yielded by shell finite element analyses, performed in the code ANSYS, or (ii) reported in the literature. Finally, the computational efficiency of the proposed GBT-based beam finite element is briefly assessed.

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