Active sound irradiation reduction into cavities

• Applicant: Professor Dr.-Ing. Michael Sinapius
• Subject Area: Acoustics ; Lightweight Construction, Textile Technology
• Term: since 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 381936987

The transmission of sound into cavities such as vehicles or aircraft is usually through plane structures, e.g. the outer skin of an airplane. For the description of the sound radiation of planar structures, extensive knowledge is available in the technical literature, which describes an energy transport into the acoustic far field. Therefore, a large part of the approaches for the active reduction of sound radiation of vibrating structures in interiors is based on these findings. Numerous analytical, numerical and experimental investigations exist. In fact, however, the structural vibration interacts with the internal acoustic medium. An energy exchange takes place. In order to reduce the sound pressures in the entire interior, the interior dynamics must be considered. This can be realized, for example, by modal coupling theory in the form of decoupled acoustic eigenvectors and structural modes. The previous work of the applicants shows that it is possible to estimate the acoustic potential energy by means of frequency independent sound radiation modes. A controller, which aims at the suppression of the acoustic potential energy, has to consider only one mode shape per sound radiation mode for all frequencies and no longer one mode per discrete frequency step. This fact puts a global acoustic control with structural sensor technology into the field of the feasible. However, it is unclear to what extent parameters such as cavity dimension, structural mass and stiffness, and structural anisotropy influence the sound radiation modes. Also unexplained is the influence of irregular cavity geometries (e.g. cylinder with bottom) on the frequency dependence of the sound radiation modes.The systematic elucidation of these relationships by analytical and numerical methods as well as experimental validation are goals of the planned work.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr.-Ing. Hans Peter Monner