Tuesday, 12 October 2004 - 5:35 PM

This presentation is part of : Damage and Composites II

Buckling Optimization of a Lattice Cylindrical Shell

Georges Duvaut1, F. Lene2, and A. Noureddine2. (1) ESILV, Pôle Universitaire Léonard de Vinci, Paris-La Défense, LM2S, Université P. et M. Curie, 4 Place Jussieu, Paris, 75252, France, (2) LM2S, Université P. et M. Curie, 4 Place Jussieu, Paris, 75252, France

Lattice structures are often made in the form of thin-walled cylindrical shells reinforced with helical and circumferential ribs. In this research, an integrated equivalent stiffness model is developed to describe such a structure. The structure is defined by the following independent design variables: thickness of the lattice layer, angle of helical ribs, spacing of helical ribs, thichnesses of ribs, thickness of the skin, angle-ply of the skin. Method of Moving Asymptotes (MMA) is used to model a cylindrical lattice shell with external laminated skin. Compression axial force and global and local buckling of the shell are considered. Solution methodology is described. A numerical example of optimization of the design variables to provide the minimum value of the shell mass and to satisfy the following constraint: acting compression axial force should not cause the general buckling of the shell neither the local buckling of the helical ribs, is given. The proposed model allows analysis of the lattice structures and is not based on the finite element method which is still of little use for overall design due to model complexity and the inability to easily changes rib geometry (angle, spacing).

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