Control of the sound radiation of grid panels with active-passive-hybrid methods

Abstract

The present work deals with the acoustic properties of grid-stiffened aircraft fuselage panels. It aims at the development of passive and active-passive-hybrid (APH) acoustic treatments to improve the low-frequency sound transmission loss of these grid panels. The idea is to exploit the geometric and dynamic properties of grid panels to improve the efficiency of the acoustic treatments. The work is subdivided in several tasks. It starts with the definition and manufacturing of an aircraft relevant test specimen. A laboratory setup is build in a semi-anechoic room which permits a proper mounting, excitation and measurement of the grid panel. A finite element model of the panel is developed and validated by means of experimental modal analysis. An aircraft relevant load case is defined and implemented. For this, a synthesis of the structural vibration induced by a turbulent boundary layer is realized by using a number of loudspeakers. Based on this work, the passive and APH acoustic treatments will be developed and implemented in the sequel of the project.