Hybrid FE-SEA Modeling and Experimental Validation of an Aircraft Floor Structure for the Analysis of Vibration Isolators

The Hybrid FE-SEA method is a recently developed numerical technique that deals with the so-called mid-frequency problem. Such problems involve the dynamic analysis of systems that include, at the same frequency range, components with high and low modal density. Systems with a reduced number of modes are usually modeled using deterministic methods, as the Finite Element (FE) Method, while modal dense systems need to be treated by means of statistical methods such as the Statistical Energy Analysis (SEA). Neither FE nor SEA can properly describe a system that displays the mid-frequency behavior due to a prohibitive computational cost (FE) or the lack of accuracy (SEA). The floor structure of an aircraft is a typical case of a mid frequency problem, where the floor beams are relatively rigid and have very few modes while the floor panels have a very high modal density. These characteristics considerably complicate the design of the vibration isolators installed between the floor beams and the floor panels. In this study, the floor structure is modeled using the Hybrid FE-SEA method, with the floor beams as FE subsystems and the floor panels as SEA subsystems. The model of each component is separately validated through experimental tests, and later coupled as a Hybrid FE-SEA model. Finally, the numerical results from the Hybrid FE-SEA model are compared with experimental results validating its performance.