Stéphane Grihon

TL;DR: An automatic method to combine several local surrogate models to build accurate and smooth approximation of discontinuous functions that are to be used in structural optimization problems and is found to improve the accuracy of the approximation.

Abstract: In this paper, an optimization procedure based on multi-phase topology optimization is developed to determine the optimal stacking sequence of laminates made up of conventional plies oriented at ?45°, 0°, 45 and 90°. The formulation relies on the SFP (Shape Functions with Penalization) parameterization, in which the discrete optimization problem is replaced by a continuous approach with a penalty to exclude intermediate values of the design variables. In this approach, the material stiffness of each physical ply is expressed as a weighted sum over the stiffness of the candidate plies corresponding to ?45°, 0°, 45 and 90° orientations. In SFP, two design variables are needed for each physical ply in the laminate to parameterize the problem with respect to the 4 candidate orientations. Even if only constant stiffness laminates of constant thickness are considered in this paper, specific design rules used in aeronautics for composite panels (i.e., no more than a maximum number of consecutive plies with the same orientation in the stacking sequence) are however formulated and taken into account in the optimization problem. The methodology is demonstrated on an application. It is discussed how the different design rules can affect the solution.

TL;DR: A review of methods and tools developed and applied at AIRBUS to deliver automated sizing for aircraft structures along their development is presented in this paper, where the major stakes for the future are discussed.

TL;DR: Sequential Convex Programming, Derivative Free Optimization techniques (DFO), Surrogate Based Optimization and Genetic Algorithm approaches are compared in the design of stiffened aircraft panels with respect to local and global instabilities (buckling and collapse).