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Optimisation multi-objectifs à base de métamodèle pour les procédés de mise en forme

Abstract : Cost saving and product improvement have always been important goals in the metal forming industry. To achieve them, metal forming processes need to be optimized, which consequently requires solving optimization problems. Usually these problems have multiple objectives; they aim at minimizing several objective functions in the presence of several explicit and implicit constraints. Each function evaluation is quite time consuming. To solve this type of problems, a robust and efficient algorithm is developed. It consists in coupling an evolutionary algorithm (a multi-objective genetic algorithm) with a metamodel (an approximation of the problem functions). Then, the number of expensive function evaluations can be significantly reduced by partly replacing exact evaluations with fast approximates of the objective functions. In this report, we first present the multi-objective optimization problem, multi-objective optimization (evolutionary) algorithms and the most commonly used metamodels (Chapter I). We select the elitist non-dominated sorting genetic algorithm (NSGA-II) to be coupled with the metamodel based on the meshless finite difference method. This metamodel, which is presented and enhanced within this thesis, is presented in Chapter II. In Chapter III, different coupling strategies between NSGA-II and the metamodel are investigated, C-Constant, C-Actualise, C-Updated-H1 and C-Updated-MC. The different studied methods differ in the choice of master points (the exact evaluations of the objective functions), the evolution of the metamodel, and the utilized approximation error. They are studied and compared on several analytical functions, mono-objective functions, multi-objective functions and constrained functions. The best method, C-Updated-MC, is then used to optimize metal forming processes in Chapter IV. The obtained results show the efficiency of our method.
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Submitted on : Wednesday, April 6, 2011 - 4:32:08 PM
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  • HAL Id : pastel-00583805, version 1

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Mohsen Ejday. Optimisation multi-objectifs à base de métamodèle pour les procédés de mise en forme. Matériaux. École Nationale Supérieure des Mines de Paris, 2011. Français. ⟨NNT : 2011ENMP0009⟩. ⟨pastel-00583805⟩

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