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  • Structural Design and Developme,nt of ISOGRID Cylinder for Propellant Tank

    Paper number

    IAC-05-C2.1.A.08

    Author

    Mr. Joon-Tae Yoo, Korea Aerospace Research Institute, Korea

    Coauthor

    Dr. Young-Soon Jang, Korea Aerospace Research Institute, Korea

    Coauthor

    Dr. Yeong-Moo Yi, Korea Aerospace Research Institute, Korea

    Year

    2005

    Abstract
    There are several methods to reinforce the cylindrical structure of fuel tank for light weight design, like skin-stringer structure and semi-monocoque structure. Isogrid is one of the reinforced structures to improve buckling load of structures.  It has advantages for the complex load cases of internal pressure loads and external loads. It is a reinforced structure using a lattice of intersecting ribs forming an array of equilateral triangles. The cylindrical isogrid structure acts as an isotropic material. So it can be averaged to form an equivalent stiffness of an isotropic layer. To form the isogrid structure, triangle shaped grids are cut by mechanical milling from a flat plate or a chemically milled plate. So the isogrid structure concept is used in such aerospace structures as nose fairings, adapters, cylindrical sections of propellant tanks. Structural design, development and structural test results of aluminum isogrid structures are described in this paper. Two kinds of isogrid structures are made, which are panels and cylinders with 1 m in diameter and 2 4m in diameter . Formability and structural strength of isogrid panels are studied. Several panels are made in different shapes of grids and are tested for the compressive buckling load of the panels. Local buckling and global buckling are observed during buckling test of the panels. From the results of test, formability, buckling mode and strength of the isogrid panels are obtained. Finally, isogrid cylinder with 2 4m in diameter and 1 5m in height was prepared and is tested to find the buckling strength of the cylinder. From the results of test, formability, buckling mode and strength of the isogrid cylinder structure are obtained. Every test results are compared with those of nonlinear finite element analysis.  MSC/MARC is used for nonlinear FE analysis. Initial imperfection, which might be occurred in the panel during plastic forming, is also considered in the analysis.
    Abstract document

    IAC-05-C2.1.A.08.pdf

    Manuscript document

    IAC-05-C2.1.A.08.pdf (🔒 authorized access only).

    To get the manuscript, please contact IAF Secretariat.