The Ultimate Strength of Stiffened Panel with Overall Buckling

2011 ◽  
Vol 308-310 ◽  
pp. 1297-1301
Author(s):  
Bao Zhang ◽  
Qin Sun
Keyword(s):  
Ultimate Strength ◽  
Orthotropic Plate ◽  
Plate Theory ◽  
Stiffened Panel ◽  
Buckling Mode ◽  
Element Analysis ◽  
Buckling Behavior ◽  
Eigenvalue Method ◽  
Post Buckling ◽  
Overall Buckling

The post-buckling behavior of a stiffened panel is investigated in this paper. Firstly, the buckling mode of the stiffened panel is obtained using the linear buckling eigenvalue method. Then, the collapsing strength of the stiffened panel is calculated using the ultimate strength method based on large deflection orthotropic plate theory. In addition, nonlinear finite element analysis is performed to predict the post-buckling behavior of the stiffened panel. By comparing the model prediction and the analytical results of ultimate strength, it is shown that good accuracy can be achieved, especially for the method referring to membrane stress in mid-thickness of equivalent orthotropic plate. It suggests that the proposed method can predict the ultimate strength of whole stiffened panel accurately and effectively.

scholarly journals Effects of plies orientations and initial geometric imperfections on buckling strength of a composite stiffened panel

2018 ◽  
Vol 191 ◽  
pp. 00008
Author(s):  
Ikram Feddal ◽  
Abdellatif Khamlichi ◽  
Koutaiba Ameziane
Keyword(s):  
Stiffened Panel ◽  
Buckling Mode ◽  
Element Analysis ◽  
Geometric Imperfections ◽  
Stiffened Panels ◽  
Specific Strength ◽  
Euler Buckling ◽  
Buckling Behavior ◽  
Composite Stiffened Panel ◽  
Strength And Stiffness

The use of composite stiffened panels is common in several activities such as aerospace, marine and civil engineering. The biggest advantage of the composite materials is their high specific strength and stiffness ratios, coupled with weight reduction compared to conventional materials. However, any structural system may reach its limit and buckle under extreme circumstances by a progressive local failure of components. Moreover, stiffened panels are usually assembled from elementary parts. This affects the geometric as well as the material properties resulting in a considerable sensitivity to buckling phenomenon. In this work, the buckling behavior of a composite stiffened panel made from carbon Epoxy Prepregs is studied by using the finite element analysis under Abaqus software package. Different plies orientations sets were considered. The initial distributed geometric imperfections were modeled by means of the first Euler buckling mode. The nonlinear Riks method of analysis provided by Abaqus was applied. This method enables to predict more consistently unstable geometrically nonlinear induced collapse of a structure by detecting potential limit points during the loading history. It was found that plies orientations of the composite and the presence of geometric imperfections have huge influence on the strength resistance.

Comparative Study of Post-Buckling Load Redistribution in Stiffened Aircraft Panel With and Without Material Nonlinearity

2018 ◽  
Author(s):  
Enes Aydin ◽  
Altan Kayran
Keyword(s):  
Finite Element ◽  
Material Nonlinearity ◽  
Stiffened Panel ◽  
Effective Width ◽  
Element Analysis ◽  
Buckling Behavior ◽  
The Finite Element Analysis ◽  
Post Buckling ◽  
Buckling Coefficient ◽  
Clamped Edge

In this article, a comparative study is presented on the post-buckling load redistribution in stiffened aircraft panels modeled with and without material nonlinearity. In the first part of the study, a baseline stiffened panel is generated for further investigation of the material nonlinearity on the post-buckling behavior and on the effective width of the stiffened panel. In this respect, a stiffener section which provides classical clamped edge condition is designed by matching the compression buckling coefficient determined by the finite element analysis closely with the analytically determined buckling coefficient of the clamped edge panel. Post-buckling analysis of the stiffened panel is then performed utilizing linear and nonlinear material models in the finite element analysis and the effect of material plasticity on the post-buckling behavior of the panel is ascertained. The load distribution in the stiffened panel is investigated just before the buckling of the panel and before the collapse of the panel in the post-buckled stage. The effective widths of the panel are calculated before the collapse of the panel using the load distributions determined by the finite element analyses of the panel models with and without material nonlinearity and comparisons are made with the effective width calculated by the classical effective width formulation. It is shown that material nonlinearity accounts for higher effective width and in general the classical empirical approach gives the smallest effective width.

Effect of Matching Buckling Loads on Post-Buckling Behavior in Compliant Mechanisms

2021 ◽  
Author(s):  
A. Numić ◽  
T. W. A. Blad ◽  
F. van Keulen
Keyword(s):  
Compliant Mechanisms ◽  
Relative Length ◽  
Optimal Designs ◽  
Element Analysis ◽  
Buckling Loads ◽  
Actuation Force ◽  
Stepped Beam ◽  
Buckling Behavior ◽  
Post Buckling ◽  
Novel Method

Abstract In this paper, a novel method for stiffness compensation in compliant mechanisms is investigated. This method involves tuning the ratio between the first two critical buckling loads. To this end, the relative length and width of flexures in two architectures, a stepped beam and parallel guidance, are adjusted. Using finite element analysis, it is shown that by maximizing this ratio, the actuation force for transversal deflection in post-buckling is reduced. These results were validated experimentally by identifying the optimal designs in a given space and capturing the force-deflection characteristics of these mechanisms.

Delamination Suppression in Sandwich Beams Using Translaminar Reinforcements

1999 ◽  
Author(s):  
Brian T. Wallace ◽  
Bhavani V. Sankar ◽  
Peter G. Ifju
Keyword(s):  
Axial Compression ◽  
Sandwich Beam ◽  
Sandwich Beams ◽  
Thickness Direction ◽  
Compression Tests ◽  
Honeycomb Core ◽  
Element Analysis ◽  
Buckling Loads ◽  
Buckling Behavior ◽  
Post Buckling

Abstract The present study is concerned with translaminar reinforcement in a sandwich beam for preventing buckling of a delaminated face-sheet under axial compression. Graphite/epoxy pins are used as reinforcement in the thickness direction of sandwich beams consisting of graphite/epoxy face-sheets and a Aramid honeycomb core. Compression tests are performed to understand the effects of the diameter of the reinforcing pins and reinforcement spacing on the ultimate compressive strength of the delaminated beams. A finite element analysis is performed to understand the effects of translaminar reinforcement on the critical buckling loads and post-buckling behavior of the sandwich beam under axial compression.

Comparative Design of Orthogonally Stiffened Plates for Production and Structural Integrity—Part 1: Size Optimization

1994 ◽  
Vol 10 (03) ◽  
pp. 146-155
Author(s):  
Nicholas Hatzidakis ◽  
Michael M. Bernitsas
Keyword(s):  
Structural Integrity ◽  
Plate Theory ◽  
Plate Thickness ◽  
Stiffened Plates ◽  
Size Optimization ◽  
Element Analysis ◽  
Total Cost ◽  
Plate Buckling ◽  
Design Variables ◽  
Overall Buckling

Five alternative configurations of orthogonally stiffened plates are compared in order to identify the total cost optimum design including material and fabrication cost. Size optimization is performed within the limitations of structural component standardization for each of the five alternatives. The five optimal structures are then compared in terms of weight, fabrication, and total cost. Discrete sizing optimization is performed in this paper with two design variables, i.e., plate thickness and standardized beam cross section. Constraints are imposed on secondary and tertiary stresses computed by finite-element analysis (FEA); and on primary stresses to prevent plate buckling, stiffener tripping, and overall buckling. Confidence is established in the FEA results by making comparisons with FEA results using the effective breadth method and orthotropic plate theory. Producibility constraints dictated by standardization in shipyard practice are imposed as well.

Post-Buckling Analysis of Stiffened Laminated Panel

1988 ◽  
Vol 55 (3) ◽  
pp. 635-640 ◽  
Author(s):  
Izhak Sheinman ◽  
Yeoshua Frostig
Keyword(s):  
Variational Principle ◽  
Finite Difference ◽  
Difference Scheme ◽  
Lateral Displacement ◽  
Numerical Procedure ◽  
Stiffened Panel ◽  
Airy Stress Function ◽  
Buckling Behavior ◽  
Plate Elements ◽  
Post Buckling

An analytical-numerical procedure is applied to investigate the post-buckling behavior of a composite laminated stiffened panel. The panel is modeled by plate elements for which the nonlinear equations are derived (via a variational principle) in terms of the lateral displacement and Airy stress function, and treated by resolving the variables into eigenfunctions in conjunction with a finite-difference scheme.

LOCAL/DISTORTIONAL/GLOBAL MODE INTERACTION IN SIMPLY SUPPORTED COLD-FORMED STEEL LIPPED CHANNEL COLUMNS

2011 ◽  
Vol 11 (05) ◽  
pp. 877-902 ◽  
Author(s):  
P. B. DINIS ◽  
D. CAMOTIM
Keyword(s):  
Shell Element ◽  
Mode Interaction ◽  
Buckling Mode ◽  
Global Mode ◽  
Simply Supported ◽  
Elastic Plastic ◽  
Buckling Behavior ◽  
Geometrical Imperfections ◽  
Post Buckling ◽  
Cold Formed Steel

This paper reports the results of a numerical investigation concerning the elastic and elastic-plastic post-buckling behavior of cold-formed steel-lipped channel columns affected by local/distortional/global (flexural-torsional) buckling mode interaction. The results presented and discussed are obtained by means of analyses performed in the code ABAQUS and adopting column discretizations into fine four-node isoparametric shell element meshes. The columns analysed (i) are simply supported (locally/globally pinned end sections with free warping), (ii) have cross-section dimensions and lengths ensuring equal local, distortional, and global (flexural-torsional) critical buckling loads, thus maximizing the mode interaction phenomenon under scrutiny, and (iii) contain critical-mode initial geometrical imperfections exhibiting different configurations, all corresponding to linear combination of the three "competing" critical buckling modes. After briefly addressing the lipped channel column "pure" global post-buckling behavior, one presents and discusses in detail numerical results concerning the post-buckling behavior of similar columns experiencing strong local/distortional/global mode interaction effects. These results consist of (i) elastic (mostly) and elastic-plastic equilibrium paths, (ii) curves and figures providing the evolution of the deformed configurations of several columns (expressed as linear combinations of their local, distortional, and global components) and, for the elastic-plastic columns, (iii) figures enabling a clear visualization of (iii1) the location and growth of the plastic strains, and (iii2) the characteristics of the failure mechanisms more often detected in this work.

scholarly journals Numerical Simulation of Buckling and Post-Buckling Behavior of a Central Notched Thin Aluminum Foil with Nonlinearity in Consideration

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 582 ◽  
Author(s):  
Mahdieh Shahmardani ◽  
Per Ståhle ◽  
Md Shafiqul Islam ◽  
Sharon Kao-Walter
Keyword(s):  
Mode Shape ◽  
Tensile Loading ◽  
Width Ratio ◽  
Plastic Behavior ◽  
Yield Limit ◽  
Buckling Mode ◽  
Buckling Stress ◽  
Buckling Behavior ◽  
Sheet Width ◽  
Post Buckling

In thin notched sheets under tensile loading, wrinkling appears on the sheet surface, specifically around the cracked area. This is due to local buckling and compression stresses near the crack surfaces. This study aims to numerically study the buckling behavior of a thin sheet with a central crack under tension. A numerical model of a notched sheet under tensile loading is developed using the finite element method, which considers both material and geometrical nonlinearity. To overcome the convergence problem caused by the small thickness-to-length/width ratio and to stimulate the buckling, an imperfection is defined as a small perturbation in the numerical model. Both elastic and elasto-plastic behavior are applied, and the influence of them is studied on the critical buckling stress and the post-buckling behavior of the notched sheet. Numerical results for both elastic and elasto-plastic behavior reflect that very small perturbations need more energy for the activation of buckling mode, and a higher buckling mode is predominant. The influences of different parameters, including Poisson’s ratio, yield limit, crack length-to-sheet-width ratio, and the sheet aspect ratio are also evaluated with a focus on the critical buckling stress and the buckling mode shape. With increase in Poisson’s ratio. First, the critical buckling stress reduces and then remains constant. A higher yield limit results in increases in the critical buckling stress, and no change in the buckling mode shape while adopting various crack length-to-sheet-width ratios, and the sheet aspect ratio changes the buckling mode shape.

Imperfection Sensitivity of Post-Buckling Behavior and Vibration Response in Pre- and Post-Buckled Regions of Nanoscale Plates Considering Surface Effects

2018 ◽  
Vol 10 (03) ◽  
pp. 1850027 ◽  
Author(s):  
Raheb Gholami ◽  
Reza Ansari
Keyword(s):  
Thermal Environment ◽  
Plate Theory ◽  
Displacement Vector ◽  
Vibration Response ◽  
Hamilton’S Principle ◽  
Imperfection Sensitivity ◽  
Hamilton's Principle ◽  
External Work ◽  
Buckling Behavior ◽  
Post Buckling

This paper aims to investigate the imperfection sensitivity of the post-buckling behavior and the free vibration response under pre- and post-buckling of nanoplates with various edge supports in the thermal environment. Formulation is based on the higher-order shear deformation plate theory, von Kármán kinematic hypothesis including an initial geometrical imperfection and Gurtin–Murdoch surface stress elasticity theory. The discretized nonlinear coupled in-plane and out-of-plane equations of motion are simultaneously obtained using the variational differential quadrature (VDQ) method and Hamilton’s principle. To this end, the displacement vector and nonlinear strain–displacement relations corresponding to the bulk and surface layers are matricized. Also, the variations of potential strain energies, kinetic energies and external work are obtained in matrix form. Then, the VDQ method is employed to discretize the obtained energy functional on space domain. By Hamilton’s principle, the discretized quadratic form of nonlinear governing equations is derived. The resulting equations are solved employing the pseudo-arc-length technique for the post-buckling problem. Moreover, considering a time-dependent small disturbance around the buckled configuration, the vibrational characteristics of pre- and post-buckled nanoplates are determined. The influences of initial imperfection, thickness, surface residual stress and temperature rise are examined in the numerical results.

Onset and Post Buckling of Pipe-in-Pipe’s Helical Buckling Using Improved Energy Method

2018 ◽  
Author(s):  
Lixin Gong
Keyword(s):  
Potential Energy ◽  
Energy Method ◽  
Normal Force ◽  
Horizontal Wells ◽  
Energy Methods ◽  
Buckling Mode ◽  
Buckling Behavior ◽  
Post Buckling ◽  
Helical Buckling ◽  
Remarkable Agreement

The purpose of this paper is to present theoretical solutions based on an improved energy method for predicting the helical buckling (HB) behavior of pipes in vertical, inclined, and horizontal wells. The energy method has been applied to solve the pipe-in-pipe’s (PIP) helical buckling behavior since Lubinski, et al [2] in the 1950’s. However, in the preceding studies, the energy methods are not yet completely correct because the pipe’s potential energy of the distributed contact normal force induced by the helical buckling was considered to be negligible. This deficiency caused improper deductive procedures. In this paper, the energy method is improved by adding the term of the potential energy of the distributed contact normal force. With this improvement, not only can the PIP’s critical helical buckling forces be successfully derived, but it also provides a deeper insight on the PIP’s helical buckling onset, as well as the post helical buckling behavior. For inclined and horizontal wells, equations are provided to determine the critical forces required to initiate the helical buckling mode for both “long” and “short” pipes. In addition, the post buckling behavior is also described, and a new concept of helical buckling zone (HBZ) for “short” pipes is introduced based on the force-pitch plots as an area in-between the helical buckling’s onset curve and the classical Lubinski curve. Finite element ABAQUS models have also been utilized to confirm the analysis using the improved energy method. And the ABAQUS results show remarkable agreement with the theoretical solutions.

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