OPTIMAL DESIGN OF STRUCTURAL INTERFACES BY A POWER FLOW MODE APPROACH

Abstract eng:
Complex mechanical structures usually encountered in the automotive or aerospace industries are composed of an assembly of several components, often exhibiting different mechanical properties and joined at their interfaces by different junction types. The various dynamic behaviors of these substructures and the applied external loadings may generate important forces on the main structure, resulting in high acceleration responses of the on-board equipment, potentially affecting their performance, reliability and security. It is therefore necessary to protect these components from these harsh interface loadings by isolating them from the rest of the structure. A variant of power flow mode methods, dedicated to low frequency vibrations, is presented which enables to dynamically characterize these structural interfaces. It is based on the imaginary part of the dynamic flexibility matrix, allowing to determine eigenvalues and eigenforces which represent qualitative and quantitative information on the power flowing inside the structure, respectively. This method is applied to study the power transmitted at the interface, making it possible to identify the direction associated to some dominant power flow patterns and to quantify their contributions. An optimal design procedure of such interfaces, with regard to their mechanical parameters (i.e. stiffness), is further proposed. Both mono-objective and robust multi-objective procedures are implemented and compared to optimize the derived power flow variables. The whole procedure is applied to a simplified coupled structure illustrating structural vibration phenomena on space-launchers.

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