Coupling functions treatment in a bi-level optimization process

International audience ; The increasing complexity of industrial products and the economic competition have led to deep changes in the way industries work. The designer has to face two main problems : on the first hand the optimization of the product quality, and on the second hand the organization between the different services that work together to produce the final product. The optimization of complex engineering systems is often both a multi-objective optimization process - each service, discipline has to fulfill several objectives - and a multidisciplinary optimization process - several disciplines are required. Methodologies that can perform simultaneously multi-objective and multidisciplinary optimization while discipline autonomy is guaranteed are needed. COSMOS methodology has been developed for this purpose. It tries to give the maximum of freedom to each discipline and so, the way coupling between discipline is handled plays a crucial role. However, the treatment of coupling functions in COSMOS has not been studied yet. In this paper, based on a simplified model of a multidisciplinary multi-objective problem, test problems have been implemented with COSMOS in order to study how it deals with coupled functions. We show that under some assumptions on the objective functions, satisfying results are found, but they cannot be guaranteed in the general case.