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Buckling Constraint

The Experts below are selected from a list of 84 Experts worldwide ranked by ideXlab platform

Chunxiao Zhou – 1st expert on this subject based on the ideXlab platform

  • fast procedure for non uniform optimum design of stiffened shells under Buckling Constraint
    Structural and Multidisciplinary Optimization, 2017
    Co-Authors: Bo Wang, Kuo Tian, Gang Li, Chunxiao Zhou

    Abstract:

    For tailoring the non-uniform axial compression, each sub-panel of stiffened shells should be designed separately to achieve a high load-carrying efficiency. Motivated by the challenge caused by numerous variables and high computational cost, a fast procedure for the minimum weight design of non-uniform stiffened shells under Buckling Constraint is proposed, which decomposes a hyper multi-dimensional problem into a hierarchical optimization with two levels. To facilitate the post-Buckling optimization, an efficient equivalent analysis model of stiffened shells is developed based on the Numerical Implementation of Asymptotic Homogenization Method. In particular, the effects of non-uniform load, internal pressure and geometric imperfections are taken into account during the optimization. Finally, a typical fuel tank of launch vehicle is utilized to demonstrate the effectiveness of the proposed procedure, and detailed comparison with other optimization methodologies is made.

Bo Wang – 2nd expert on this subject based on the ideXlab platform

  • fast procedure for non uniform optimum design of stiffened shells under Buckling Constraint
    Structural and Multidisciplinary Optimization, 2017
    Co-Authors: Bo Wang, Kuo Tian, Gang Li, Chunxiao Zhou

    Abstract:

    For tailoring the non-uniform axial compression, each sub-panel of stiffened shells should be designed separately to achieve a high load-carrying efficiency. Motivated by the challenge caused by numerous variables and high computational cost, a fast procedure for the minimum weight design of non-uniform stiffened shells under Buckling Constraint is proposed, which decomposes a hyper multi-dimensional problem into a hierarchical optimization with two levels. To facilitate the post-Buckling optimization, an efficient equivalent analysis model of stiffened shells is developed based on the Numerical Implementation of Asymptotic Homogenization Method. In particular, the effects of non-uniform load, internal pressure and geometric imperfections are taken into account during the optimization. Finally, a typical fuel tank of launch vehicle is utilized to demonstrate the effectiveness of the proposed procedure, and detailed comparison with other optimization methodologies is made.

  • non probabilistic reliability based design optimization of stiffened shells under Buckling Constraint
    Thin-walled Structures, 2015
    Co-Authors: Zeng Meng, Bo Wang, Gang Li, Kai Zhang

    Abstract:

    Stiffened shells are affected by numerous uncertainty factors, such as the variations of manufacturing tolerance, material properties and environment aspects, etc. Due to the expensive experimental cost of stiffened shell, only a limited quantity of statistics about its uncertainty factors are available. In this case, an unjustified assumption of probabilistic model may result in misleading outcomes of reliability-based design optimization (RBDO), and the non-probabilistic convex method is a promising alternative. In this study, a hybrid non-probabilistic convex method based on single-ellipsoid convex model is proposed to minimize the weight of stiffened shells with uncertain-but-bounded variations, where the adaptive chaos control (ACC) method is applied to ensure the robustness of search process of single-ellipsoid convex model, and the particle swarm optimization (PSO) algorithm together with smeared stiffener model are utilized to guarantee the global optimum design. A 3 m-diameter benchmark example illustrates the advantage of the proposed method over RBDO and deterministic optimum methods for stiffened shell with uncertain-but-bounded variations.

József Farkas – 3rd expert on this subject based on the ideXlab platform

  • 8 – Welded Stiffened Cylindrical and Conical Shells
    Design and Optimization of Metal Structures, 2020
    Co-Authors: József Farkas, Karoly Jarmai

    Abstract:

    This chapter discusses welded stiffened cylindrical and conical shells. The economy of some structural types is demonstrated by the comparison of minimum costs of different structural versions. Such a comparison has been performed for various kinds of stiffened cylindrical shells, such as ring stiffeners, external pressure, ring stiffeners, bending, stringer stiffeners, axial compression and bending, stringer stiffeners, bending, ring and stringer stiffeners, axial compression, and external pressure. The optimum design problem is solved for a slightly conical shell loaded in external pressure with equidistant ring-stiffeners of a welded square box section. The optimum number of shell segments is found, which minimizes the cost function and fulfils the design Constraints. The thickness of each shell segment is calculated from the shell Buckling Constraint. This Constraint is similar to that for circular cylindrical shells, but an equivalent thickness and segment length is used according to the DNV design rules. The dimensions of ring-stiffeners for each shell segment are determined on the basis of the ring Buckling Constraint. This Constraint is expressed by the required moment of inertia of the ring-stiffener cross-section. The cost function includes the cost of material, forming of plate elements into shell shape, assembly, welding, and painting. The fabrication cost function is formulated according to the fabrication sequence. The forming, welding, and painting costs play an important role in the total cost.

  • Minimum cost design of a cellular plate loaded by uniaxial compression
    Structural and Multidisciplinary Optimization, 2012
    Co-Authors: Karoly Jarmai, József Farkas

    Abstract:

    Cellular plates are constructed from two base plates and an orthogonal grid of stiffeners welded between them. Halved rolled I-section stiffeners are used for fabrication aspects. The torsional stiffness of cells makes the plate very stiff. In the case of uniaxial compression the Buckling Constraint is formulated on the basis of the classic critical stress derived from the Huber’s equation for orthotropic plates. The cost function contains the cost of material, assembly and welding and is formulated according to the fabrication sequence. The unknown variables are the base plate thicknesses, height of stiffeners and numbers of stiffeners in both directions. The cellular plate is lighter and cheaper than the plate stiffened on one side. The Particle Swarm Optimization and the IOSO techniques are used to find the optimum. PSO contains crazy bird and dynamic inertia reduction criteria, IOSO is based on a response surface technology.