In several industrial applications, the vibrating structures are in contact with a fluid (fluid around the hulls of a boats, reservoirs, heat exchangers in power plants, ...), but the dynamic behavior of the structure can be significantly modified by the presence of the fluid. The sizing must take into account the effects of fluid-structure interaction. These applications require an effective coupling. In addition, the dynamic analysis of the industrial systems is often expensive from the numerical point of view. For the coupling fluid structure finite elements models, the importance of the size reduction becomes obvious because the fluid’s freedom degrees will be added to those of the structure. A proposed condensation method will be used to reduce the matrixes size. Traditionally, the study of the fluid-structure interaction is based on a deterministic approach where all the parameters used in the model have a fixed value. But it suffices having conducted a few experimentations to realize the limitations of such modeling. Hence it need to take into accounts the uncertainty on the parameters of mechanical systems. In this thesis, we deal with the simulation of vibro-acoustic problems. The first part presents a numerical and analytical study of deterministic problems without model’s reduction, based on a non-symmetric formulation displacement/pressure and on a symmetric formulation displacement/pressure and velocity potential. In the second part of this work, two methods are proposed to reduce the model : modal analysis and modal synthesis for solving vibro-acoustic problems of large sizes modeled by finite elements method. The developed modal synthesis method is coupling dynamic substructure of Craig and Bampton type and acoustic subdomain based on a pressure formulation. To take into account the parameter’s uncertainties of the coupled system, we have developed a numerical stochastic method of the modal synthesis and modal analysis extended to reliability study, based on the FORM and SORM approaches. These approaches will allow us to solve the vibro-acoustic problems without using classical procedure. It may become prohibitive in terms of computation time. Several academic and industrial examples are studied to validate the proposed methods. The numerical study is performed using a code developed with MATLAB coupled with the commercial code ANSYS in order to evaluate the reliability of systems. The comparison of numerical, analytical and experimental results enables us to jointly validate the calculation process and the proposed methods in the domain of frequency analysis and reliability study of submerged structures. From the industrial point of view, our research work aim is to promote the introduction of the uncertainty’s culture during modeling in the context of design processes.
