Buckling Analysis

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Rakesh K. Kapania - One of the best experts on this subject based on the ideXlab platform.

  • Buckling Analysis of unitized curvilinearly stiffened composite panels
    Composite Structures, 2016
    Co-Authors: Wei Zhao, Rakesh K. Kapania
    Abstract:

    Abstract Innovative manufacturing technology has led to the fabrication of complex shape and multi-functional structures by using the concept of integrated and bonded unitized structural components. To study the stability behavior of such structural designs, this paper presents an efficient finite element Buckling Analysis of unitized stiffened composite panel stiffened by arbitrarily shaped stiffeners. A first-order shear-deformation theory is employed for both the panel and the stiffeners. Displacement compatibility conditions are imposed at the panel-stiffeners interfaces. To obviate remeshing when the stiffener shape changes, the stiffeners’ geometry and displacement are expressed in terms of those of the panel middle surface through compatibility conditions that make use of the interpolation polynomials employed in the finite element method. To accommodate any shaped stiffeners, a generalized geometry parametrization tool is developed to parameterize the shape of the stiffeners including the stiffener placement and the stiffener geometric curvature. Convergence and validation studies using the present method for the Buckling Analysis of stiffened isotropic and composite panels are conducted to illustrate the accuracy of the present method. Parametric studies show that the stiffener placement, the stiffener geometric curvature, the stiffener depth ratio (height-to-width ratio) and laminates fiber ply orientation influence both the plate bucking load and the correspond Buckling mode shape. The tailoriability of the stiffeners shape and the laminates fiber ply orientation provides an enhanced design space in the structural design for improving the structural stability.

  • Buckling Analysis of Curvilinearly Stiffened Composite Panels with Cracks
    55th AIAA ASME ASCE AHS ASC Structures Structural Dynamics and Materials Conference, 2014
    Co-Authors: Mohamed Jrad, Arafat I. Khan, Rakesh K. Kapania
    Abstract:

    STIFFENERS attached to composite panels may significantly increase the overall Buckling load of the resultant stiffened structure. First, Buckling Analysis of a composite panel with attached longitudinal stiffeners under compressive loads is performed using Ritz method with trigonometric functions. Results are then compared to those from ABAQUS FEA for different shell elements. The case of composite panel with one, two, and three stiffeners is investigated. The effect of the distance between the stiffeners on the Buckling load is also studied. The variation of the Buckling load and Buckling modes with the stiffeners’ height is investigated. It is shown that there is an optimum value of stiffeners’ height beyond which the structural response of the stiffened panel is not improved and the Buckling load does not increase. Furthermore, there exist different critical values of stiffener’s height at which the Buckling mode of the structure changes. Next, Buckling Analysis of a composite panel with two straight stiffeners and a crack at the center is performed. Finally, Buckling Analysis of a composite panel with curvilinear stiffeners and a crack at the center is also conducted. ABAQUS is used for these two examples and results show that panels with a larger crack have a reduced Buckling load. It is shown also that the Buckling load decreases slightly when using higher order 2D shell FEM elements.

Wei Zhao - One of the best experts on this subject based on the ideXlab platform.

  • Buckling Analysis of unitized curvilinearly stiffened composite panels
    Composite Structures, 2016
    Co-Authors: Wei Zhao, Rakesh K. Kapania
    Abstract:

    Abstract Innovative manufacturing technology has led to the fabrication of complex shape and multi-functional structures by using the concept of integrated and bonded unitized structural components. To study the stability behavior of such structural designs, this paper presents an efficient finite element Buckling Analysis of unitized stiffened composite panel stiffened by arbitrarily shaped stiffeners. A first-order shear-deformation theory is employed for both the panel and the stiffeners. Displacement compatibility conditions are imposed at the panel-stiffeners interfaces. To obviate remeshing when the stiffener shape changes, the stiffeners’ geometry and displacement are expressed in terms of those of the panel middle surface through compatibility conditions that make use of the interpolation polynomials employed in the finite element method. To accommodate any shaped stiffeners, a generalized geometry parametrization tool is developed to parameterize the shape of the stiffeners including the stiffener placement and the stiffener geometric curvature. Convergence and validation studies using the present method for the Buckling Analysis of stiffened isotropic and composite panels are conducted to illustrate the accuracy of the present method. Parametric studies show that the stiffener placement, the stiffener geometric curvature, the stiffener depth ratio (height-to-width ratio) and laminates fiber ply orientation influence both the plate bucking load and the correspond Buckling mode shape. The tailoriability of the stiffeners shape and the laminates fiber ply orientation provides an enhanced design space in the structural design for improving the structural stability.

Broderick H Coburn - One of the best experts on this subject based on the ideXlab platform.

  • Buckling Analysis of stiffened variable angle tow panels
    Composite Structures, 2014
    Co-Authors: Broderick H Coburn, Zhangming Wu, Paul M Weaver
    Abstract:

    Variable angle tow (VAT) laminates have previously shown enhanced Buckling performance compared to conventional straight fibre laminates. In this study, an analytical method is developed for the Buckling Analysis of a novel blade stiffened VAT panel to allow this potential to be more fully exploited. The preBuckling and Buckling Analysis, performed on a representative section of a blade stiffened VAT panel, are based on a generalised Rayleigh–Ritz procedure. The Buckling Analysis includes a first order shear deformation theory by introducing additional shape functions for transverse shear and is therefore applicable to structures with thick skins relative to characteristic length. Modelling of the stiffener is achieved with two approaches; idealisation as a beam attached to the skin’s midplane and as a rigidly attached plate. Comparing results with finite element Analysis (Abaqus) for selected case studies, local Buckling errors for the beam model and plate model were found to be less than 3% and 2% respectively, whilst the beam model error for global Buckling was between 3% and 10%. The analytical model provides an accurate alternative to the computationally expensive finite element Analysis and is therefore suitable for future work on the design and optimisation of stiffened VAT panels.

Paul M Weaver - One of the best experts on this subject based on the ideXlab platform.

  • Buckling Analysis of stiffened variable angle tow panels
    Composite Structures, 2014
    Co-Authors: Broderick H Coburn, Zhangming Wu, Paul M Weaver
    Abstract:

    Variable angle tow (VAT) laminates have previously shown enhanced Buckling performance compared to conventional straight fibre laminates. In this study, an analytical method is developed for the Buckling Analysis of a novel blade stiffened VAT panel to allow this potential to be more fully exploited. The preBuckling and Buckling Analysis, performed on a representative section of a blade stiffened VAT panel, are based on a generalised Rayleigh–Ritz procedure. The Buckling Analysis includes a first order shear deformation theory by introducing additional shape functions for transverse shear and is therefore applicable to structures with thick skins relative to characteristic length. Modelling of the stiffener is achieved with two approaches; idealisation as a beam attached to the skin’s midplane and as a rigidly attached plate. Comparing results with finite element Analysis (Abaqus) for selected case studies, local Buckling errors for the beam model and plate model were found to be less than 3% and 2% respectively, whilst the beam model error for global Buckling was between 3% and 10%. The analytical model provides an accurate alternative to the computationally expensive finite element Analysis and is therefore suitable for future work on the design and optimisation of stiffened VAT panels.

Dong-ho Choi - One of the best experts on this subject based on the ideXlab platform.

  • Iterative Buckling Analysis for Steel Tower Members in Cable-Stayed Bridges
    IABSE Symposium Report, 2009
    Co-Authors: Dong-ho Choi, Soo-ho Song
    Abstract:

    A new method of iterative Buckling Analysis is proposed for obtaining the effective length of steel tower members in cable-stayed bridges. The concept of a fictitious axial force, which is derived from the relation between the individual Buckling limit of each member and the overall Buckling of the bridge, is introduced to overcome the problem associated with system Buckling Analysis. After presenting the proposed method, it is applied to an example cable-stayed bridge with different girder depths. The results demonstrate that the proposed method not only provides reasonable outcomes by correcting the inaccuracies seen in system Buckling Analysis, but is also convenient for practical applications.

  • New method of inelastic Buckling Analysis for steel frames
    Journal of Constructional Steel Research, 2008
    Co-Authors: Dong-ho Choi
    Abstract:

    Abstract In general, the concept of bifurcation stability cannot be used to evaluate the critical load of typical steel frames that have geometric imperfections and primary bending moment due to transverse loads. These cases require a plastic zone or plastic hinge Analysis based on the concept of limit-load stability instead. However, such analyses require large computation times and complicated theories that are unsuitable for practical designs. The present paper proposes a new method of inelastic Buckling Analysis in order to determine the critical load of steel frames. This inelastic Analysis is based on the concept of modified bifurcation stability using a tangent modulus approach and the column strength curve. Criteria for an iterative eigenvalue Analysis are proposed in order to consider the primary bending moment as well as the axial force by using the interaction equation for beam–column members. The validity and applicability of the proposed inelastic Buckling Analysis were evaluated alongside elastic Buckling Analysis and refined plastic hinge Analysis. Simple columns with geometric imperfections and a four-story plane frame were analyzed as benchmark problems. The results show that the proposed inelastic Buckling Analysis suitably evaluates the critical load and failure modes of steel frames, and can be a good alternative for the evaluation of critical load in the design of steel frames.

  • Applicability of Inelastic Buckling Analysis for Evaluation of Ultimate Load Carrying Capacity of Cable-Stayed Bridges
    2005
    Co-Authors: Dong-ho Choi, Dong-hyun Ha
    Abstract:

    This paper performed elastic Buckling Analysis, inelastic Buckling Analysis and nonlinear elasto-plastic Analysis to evaluate load carrying capacity of cable-stayed bridges. Elastic Buckling Analysis uses numerical eigenvalue calculation without considering nonlinear and inelastic behavior of main members. Inelastic Buckling Analysis can predict inelastic behavior of main members approximately using column strength curve prescribed in Korean Highway Bridge Specifications (2000) and numerical iterative-eigenvalue calculation. Nonlinear elasto-plastic Analysis that considers nonlinear and elasto-plastic behavior of main members are performed using incremental-iterative method in ABAQUS to obtain load carrying capacities for numerical models of ideal cable-stayed bridges and the model of Dolsan Great bridge. Applicability of inelastic Buckling Analysis is examined compared to nonlinear elasto-plastic Analysis. As a result, the converged eigenvalues of inelastic Buckling Analysis show good approximation for the load proportional factors of nonlinear elasto-plastic Analysis.