1 Copyright © 1999 by Instituto Nacional de Pesquisas Espaciais (INPE). All rights reserved. Instituto Nacional de Pesquisas Espaciais, owner of the copyright of the work “Application of Structural Optimization on Redesigning the French-Brazilian Micro Satellite” on this 30 th day of March 1999, grants to The MacNeal-Schwendler Corporation a royalty-free, irrevocable, non-exclusive, worldwide license to publish the work in MSC’s proceedings for its 1999 Aerospace User’s Conference. APPLICATION OF STRUCTURAL OPTIMIZATION ON REDESIGNING THE FRENCH-BRAZILIAN MICRO SATELLITE Fernanda M. N. Ravetti * ; Mário Kataoka Filho * and Creto A. Vidal + * Instituto Nacional de Pesquisas Espaciais – DMC/INPE Av. dos Astronautas, 1758 12.227-010 São José dos Campos, SP – Brazil e-mail: {fernanda, kataoka}@dem.inpe.br – phone: +55-12-345-6245 + Universidade Federal do Ceará – DC/UFC Campus do PICI, Bloco 910, 60455-760 Fortaleza, CE – Brazil e-mail: cvidal@lia.ufc.br – phone:+55 85 287-1333 ABSTRACT The French-Brazilian Micro Satellite (FBMS) is a scientific satellite, which will be piggyback launched by the rocket Ariane 5. Its most critical design constraints are: the lower bound of 40.0 Hz on the first natural frequency, in order to avoid coupling between the rocket excitation modes and the natural vibration modes of the satellite; and the upper bound of 10.5 kg on the structural mass. The structure of the FBMS is composed of a cylindrical aluminum alloy adapter for connection with the rocket, and eight sandwich panels (each composed of three layers) that define its topology. In this paper, we show the importance of structural optimization and design sensitivity analysis in the redesign cycles of Space Structures, by presenting all the steps taken and the difficulties encountered as we tried to maximize the first natural frequency from the low value of 18.78 Hz obtained with the first trial design, while maintaining the structural mass bellow the predefined upper bound. All the modal and sensitivity analyses as well as the optimization steps were performed using MSC/NASTRAN. The design variable space for the structural optimization steps was composed of the thicknesses of the faces and core of the sandwich panels.