American Institute of Aeronautics and Astronautics 1 A NEW APPROACH IN STACKING SEQUENCE OPTIMIZATION OF COMPOSITE LAMINATES USING GENESIS STRUCTURAL ANALYSIS AND OPTIMIZATION SOFTWARE Juan Pablo Leiva * , Dipankar K. Ghosh + and Naveen Rastogi ⊥ * GENESIS Project Manager, Vanderplaats Research and Development, Inc., Senior Member AIAA + Product Manager, Vanderplaats Research and Development, Inc., Member AIAA ⊥ Technical Fellow, CAE & Optimization, Visteon Corporation, Senior Member AIAA Copyright 2002 by Vanderplaats Research and Development, Inc. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission ABSTRACT A simple approach to stacking sequence optimization of composite laminates is presented. The original stacking sequence problem is solved using an equivalent sizing optimization problem with continuous design variables. INTRODUCTION The composite laminate design process typically involves optimization of the following four parameters: 1. Ply (or lamina) material, 2. Ply thickness, 3. Ply orientation, and 4. Stacking (or lay-up) sequence. The true optimization of a composite laminate, simultaneously considering the coupling effects of the four design parameters mentioned above, is a mathematical challenge in structural optimization. The optimization of ply material is, perhaps, the most complex of all because of the inherent possibility of designing a hybrid laminate consisting of two or more material types. Recent work by Grosset, Venkataraman and Haftka 1 is an attempt to address the issue of multi-material optimization for hybrid composite laminates. Numerous analytical techniques are available to optimize the ply thickness and orientation of a composite laminate. While majority of the commercially available structural optimization codes treat ply thickness and orientation as continuous design variables, GENESIS 2 has been recently enhanced to handle them as discrete and/or continuous design variables during the laminate design process. Once ply material, thicknesses and orientations in the laminate are known, a certain sequence of layers, known as laminate lay-up or stacking sequence, is assumed. However, this assumed laminate stacking sequence might not produce the optimal laminate design for a composite structure. This is especially true when the response of the laminated structure is NOT dominated by its membrane properties. One straightforward approach to stacking sequence optimization may be to evaluate all the candidate designs after material, thickness and orientation optimization has been performed, and then pick the best one. This approach, however, is computationally intensive for most practical applications, because the total number of possibilities in a laminate stacking sequence design is normally huge. For example, if a 9th AIAA/ISSMO Symposium on Multidisciplinary Analysis and Optimization 4-6 September 2002, Atlanta, Georgia AIAA 2002-5451 Copyright © 2002 by the author(s). Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.