MODELING AND SIMULATION OF BUCKLING AND POSTBUCKLING OF PLANT STEMS UNDER COMBINED LOADING CONDITIONS

2011 ◽  
Vol 03 (01) ◽  
pp. 119-130 ◽  
Author(s):  
HAO-LEI CUI ◽  
HUI-SHEN SHEN
Keyword(s):  
Axial Compression ◽  
Local Buckling ◽  
Bending Moment ◽  
Wind Pressure ◽  
Combined Loading ◽  
Equilibrium Path ◽  
Governing Equations ◽  
Postbuckling Behavior ◽  
Finite Element Package ◽  
Plant Stem

Numerical simulations for local buckling and postbuckling behavior of plant stems are presented under two combined loading cases: (1) axial compression (caused by axial grains) combined with wind pressure; and (2) bending moment (caused by eccentric axial grains) combined with wind pressure. Based on its microstructure, a hollow plant stem is modeled as a stringer stiffened multiwalled shell. The material properties of the stem are assumed to be orthotropic. The nonlinear governing equations for buckling and postbuckling of plant stems are solved through arc-length method along with Newton–Raphson technique. The numerical calculations are carried out using the finite element package ABAQUS. The results show that the postbuckling equilibrium path is unstable for plant stems subjected to axial compression or bending combined with relatively low values of wind pressure. Large reduction in buckling load and in postbuckling strength can be found even if the applied wind pressure is relatively small, which results in the easy occurrence of stem lodging.

Upheaval Buckling of Small Diameter Pipelines Induced by Strong Ground Shaking

2012 ◽  
Author(s):  
Hiroyuki Horikawa ◽  
Yoji Tsunasawa ◽  
Hajime Shinkai ◽  
Nobuhisa Suzuki
Keyword(s):  
Local Buckling ◽  
Small Diameter ◽  
Field Tests ◽  
Bending Moment ◽  
Design Guidelines ◽  
Combined Loading ◽  
Pipe Material ◽  
Effective Parameters ◽  
Ground Shaking ◽  
Upheaval Buckling

Upheaval buckling of small diameter gas pipeline occurred due to strong seismic excitation during the 2007 Niigata-ken Chuetsu-Oki earthquake whose diameters were 4″ and smaller. This paper deals with investigation of the upheaval buckling of gas pipes conducted by Ministry of Economy, Trade and Industry of Japan to establish seismic design guidelines to mitigate upheaval buckling. Sand box and field tests were conducted using small diameter pipes to simulate the upheaval buckling behaviors and construct a simple finite element model. The results clarified that the tensile properties of pipe material and pipe-soil interaction were the most effective parameters to explain the buckling behaviors. Interaction curve of pipes can be found in the relationship between compression and bending moment in the combined loading tests. The deformation behaviors of the buried pipe tests followed the interaction curve and local buckling of buried pipes occurred in lower bending moment than that of pipes not buried.

scholarly journals Large deformation behavior of functionally graded porous curved beams in thermal environment

2021 ◽  
Author(s):  
S. F. Nikrad ◽  
A. Kanellopoulos ◽  
M. Bodaghi ◽  
Z. T. Chen ◽  
A. Pourasghar
Keyword(s):  
Boundary Conditions ◽  
Volume Fraction ◽  
Thermal Environment ◽  
Ritz Method ◽  
Shear Deformation Theory ◽  
Bending Moment ◽  
Functionally Graded ◽  
Equilibrium Path ◽  
Curved Beams ◽  
Governing Equations

AbstractThe in-plane thermoelastic response of curved beams made of porous materials with different types of functionally graded (FG) porosity is studied in this research contribution. Nonlinear governing equations are derived based on the first-order shear deformation theory along with the nonlinear Green strains. The nonlinear governing equations are solved by the aid of the Rayleigh–Ritz method along with the Newton–Raphson method. The modified rule-of-mixture is employed to derive the material properties of imperfect FG porous curved beams. Comprehensive parametric studies are conducted to explore the effects of volume fraction and various dispersion patterns of porosities, temperature field, and arch geometry as well as boundary conditions on the nonlinear equilibrium path and stability behavior of the FG porous curved beams. Results reveal that dispersion and volume fraction of porosities have a significant effect on the thermal stability path, maximum stress, and bending moment at the crown of the curved beams. Moreover, the influence of porosity dispersion and structural geometry on the central radial and in-plane displacement of the curved beams is evaluated. Results show that various boundary conditions make a considerable difference in the central radial displacements of the curved beams with the same porosity dispersion. Due to the absence of similar results in the specialized literature, this paper is likely to provide pertinent results that are instrumental toward a reliable design of FG porous curved beams in thermal environment.

DESIGN, TESTING AND VALIDATION OF A COMPOSITE BOX UNDER COMBINED LOADING UP TO COLLAPSE

2010 ◽  
Vol 10 (04) ◽  
pp. 853-869 ◽  
Author(s):  
POTITO CORDISCO ◽  
CHIARA BISAGNI
Keyword(s):  
Axial Compression ◽  
Combined Loading ◽  
Structural Safety ◽  
Fe Model ◽  
Test Results ◽  
Postbuckling Behavior ◽  
Highly Nonlinear ◽  
Box Structure ◽  
Curved Panels ◽  
Restrictive Hypothesis

This paper presents part of the activities performed by Politecnico di Milano within the European research project COCOMAT, consisting of the design, testing and validation of a closed box structure made up of CFRP stringer-stiffened curved panels. The design phase is carried out using ABAQUS/Explicit with the purpose of obtaining a structure with a ratio between the collapse and the buckling load that is greater than 3 under axial compression and greater than 2 under torque. The box is manufactured by Agusta/Westland and tested at Politecnico di Milano. The first test results are used to validate the FE model, removing some restrictive hypothesis formulated during the design process. Finally, a comparison between the results under combined axial compression and torque loads obtained in the collapse test and in the FE analysis reproducing the collapse is shown. A good correlation is obtained, both in the buckling and postbuckling behavior and in the collapse modality, demonstrating the capability of the dynamic explicit analyses to capture the highly nonlinear response of the aeronautical panels. The results also show the possibility of CFRP structures working deeply in the postbuckling region if properly designed and, consequently, the possibility of a weight reduction of aerospace structures thanks to the possibility of moving up the ultimate load toward the collapse load without any loss in the structural safety.

Extending the Limits for Thick Walled Pipe (D/t<20) for External Pressure and Combined Loading

2017 ◽  
Author(s):  
Henk Smienk ◽  
Erwan Karjadi ◽  
Steven Huiskes
Keyword(s):  
Limit State ◽  
Local Buckling ◽  
Bending Moment ◽  
External Pressure ◽  
Combined Loading ◽  
Load Path ◽  
Material Models ◽  
Axial Tension ◽  
Geometrical Imperfections ◽  
2D And 3D

During the operational and installation phase of submarine pipelines, the collapse and local buckling behaviour is of interest. Existing research [1] shows conservatism in the pure collapse DNV formula for thick walled pipe. The first part of the paper will focus on the collapse behaviour of empty thick walled pipe under external pressure. Using 2D and 3D FE Analysis an investigation into the collapse behaviour of pipe with a D/t < 20 is conducted. The analysis also covers an extensive sensitivity analysis with regard to geometrical imperfections and different material models. The local buckling behaviour during the combined external pressure, bending moment and effective axial force loading encountered in the sagbend is also investigated. To obtain a realistic load path for the sagbend loading, static Flexcom analyses are performed. If the load case is not sufficient to initiate collapse because of the stiffness of the catenary due to the low D/t, the pipe will be bent to the limit state while setting the effective tension to zero. The effect of each sensitivity on the collapse and local buckle behaviour of thick walled pipe in the sagbend including effective axial tension is discussed.

Local Buckling Behavior of X100 Linepipes

2003 ◽  
Author(s):  
Nobuhisa Suzuki ◽  
Ryuji Muraoka ◽  
Alan Glover ◽  
Joe Zhou ◽  
Masao Toyoda
Keyword(s):  
Finite Element ◽  
Axial Compression ◽  
Critical Strain ◽  
Axial Stress ◽  
Local Buckling ◽  
Bending Moment ◽  
Finite Element Analyses ◽  
Design Factor ◽  
Shell Elements ◽  
Buckling Behavior

Local buckling behavior of API 5L X100 grade linepipes subjected to axial compression and/or bending moment is discussed in this paper based on results obtained by finite element analyses. Yield-to-tensile strength (Y/T) ratio and design factor were taken into account in the finite element analyses in order to discuss their effects on the local buckling behavior. The local bucking behavior of such lower strength linepipes as X60 and X80 grade linepipes is also discussed for comparison. Two-dimensional solid elements and four-node shell elements were used for the finite element modeling of the linepipes subjected to axial compression and bending moment, respectively. The study has improved the understanding of local buckling behavior of the X100 grade linepipes and observed the following trends. When a linepipe is subjected to axial compression, the critical axial stress decreases with increasing design factor and Y/T ratio. However, the nominal critical strain increases with increasing design factor and decreasing Y/T ratio. When a linepipe is subjected to bending moment, the critical bending moment decreases with increasing design factor and Y/T ratio. Similarly, the nominal critical strain increases with increasing design factor. However, the nominal critical strain increases with decreasing Y/T ratio when the design factor is less than and equal to 0.6 and decreases with decreasing Y/T ratio when the design factor is equal to 0.8.

The Influence of Loads Superposition, Deterioration Due to Cracks and Residual Stresses on the Strength of Tubular Junction

2017 ◽  
Vol 68 (6) ◽  
pp. 1267-1273
Author(s):  
Valeriu V. Jinescu ◽  
Angela Chelu ◽  
Gheorghe Zecheru ◽  
Alexandru Pupazescu ◽  
Teodor Sima ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Residual Stresses ◽  
Bending Moment ◽  
Combined Loading ◽  
Torsional Moment ◽  
Calculation Methods ◽  
State Of Stress ◽  
Cracked Structures ◽  
Total Participation ◽  
Theoretical Results

In the paper the interaction of several loads like pressure, axial force, bending moment and torsional moment are analyzed, taking into account the deterioration due to cracks and the influence of residual stresses. A nonlinear, power law, of structure material is considered. General relationships for total participation of specific energies introduced in the structure by the loads, as well as for the critical participation have been proposed. On these bases: - a new strength calculation methods was developed; � strength of tubular cracked structures and of cracked tubular junction subjected to combined loading and strength were analyzed. Relationships for critical state have been proposed, based on dimensionless variables. These theoretical results fit with experimental date reported in literature. On the other side stress concentration coefficients were defined. Our one experiments onto a model of a pipe with two opposite nozzles have been achieved. Near one of the nozzles is a crack on the run pipe. Trough the experiments the state of stress have been obtained near the tubular junction, near the tip of the crack and far from the stress concentration points. On this basis the stress concentration coefficients were calculated.

Buckling of Circular Cylindrical Shells Using a Displacement Function

1974 ◽  
Vol 96 (4) ◽  
pp. 1322-1327
Author(s):  
Shun Cheng ◽  
C. K. Chang
Keyword(s):  
Boundary Conditions ◽  
Axial Compression ◽  
Cylindrical Shells ◽  
External Pressure ◽  
Displacement Function ◽  
Combined Loading ◽  
Trial Solution ◽  
Governing Differential Equation ◽  
Circular Cylindrical Shells ◽  
The Stability

The buckling problem of circular cylindrical shells under axial compression, external pressure, and torsion is investigated using a displacement function φ. A governing differential equation for the stability of thin cylindrical shells under combined loading of axial compression, external pressure, and torsion is derived. A method for the solutions of this equation is also presented. The advantage in using the present equation over the customary three differential equations for displacements is that only one trial solution is needed in solving the buckling problems as shown in the paper. Four possible combinations of boundary conditions for a simply supported edge are treated. The case of a cylinder under axial compression is carried out in detail. For two types of simple supported boundary conditions, SS1 and SS2, the minimum critical axial buckling stress is found to be 43.5 percent of the well-known classical value Eh/R3(1−ν2) against the 50 percent of the classical value presently known.

Modelling hollow pultruded FRP profiles under axial compression: Local buckling and progressive failure

2021 ◽  
Vol 262 ◽  
pp. 113650
Author(s):  
Mohammad Alhawamdeh ◽  
Omar Alajarmeh ◽  
Thiru Aravinthan ◽  
Tristan Shelley ◽  
Peter Schubel ◽  
...  
Keyword(s):  
Axial Compression ◽  
Progressive Failure ◽  
Local Buckling

scholarly journals Confinement effects for rubberised concrete in tubular steel cross-sections under combined loading

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
A. Mujdeci ◽  
D. V. Bompa ◽  
A. Y. Elghazouli
Keyword(s):  
Axial Compression ◽  
Cross Section ◽  
Cross Sections ◽  
Image Correlation ◽  
Combined Loading ◽  
Test Results ◽  
Compression Tests ◽  
Confinement Effects ◽  
Rubber Content ◽  
Dependent Modification

AbstractThis paper describes an experimental investigation into confinement effects provided by circular tubular sections to rubberised concrete materials under combined loading. The tests include specimens with 0%, 30% and 60% rubber replacement of mineral aggregates by volume. After describing the experimental arrangements and specimen details, the results of bending and eccentric compression tests are presented, together with complementary axial compression tests on stub-column samples. Tests on hollow steel specimens are also included for comparison purposes. Particular focus is given to assessing the confinement effects in the infill concrete as well as their influence on the axial–bending cross-section strength interaction. The results show that whilst the capacity is reduced with the increase in the rubber replacement ratio, an enhanced confinement action is obtained for high rubber content concrete compared with conventional materials. Test measurements by means of digital image correlation techniques show that the confinement in axial compression and the neutral axis position under combined loading depend on the rubber content. Analytical procedures for determining the capacity of rubberised concrete infilled cross-sections are also considered based on the test results as well as those from a collated database and then compared with available recommendations. Rubber content-dependent modification factors are proposed to provide more realistic representations of the axial and flexural cross-section capacities. The test results and observations are used, in conjunction with a number of analytical assessments, to highlight the main parameters influencing the behaviour and to propose simplified expressions for determining the cross-section strength under combined compression and bending.

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