Active Control of Sound Transmission through a Curved Carbon-Fiber-Reinforced-Plastic (CFRP) Panel

Abstract

This article is focused on the development and experimental realization of an active structural acoustic control (ASAC) system for a curved carbon-fiber-reinforced-plastic (CFRP) panel. The research aims at the development of a smart lightweight fuselage structure for future aircrafts with an improved sound transmission loss at frequencies well below 1 kHz. A numerical pre-design is performed in order to define the transducers of the active system and to derive optimal sensor and actuator locations with regard to an acoustically relevant performance metric. The optimization of the type, number and location of the actuators is based on a full system description using numerical models for the disturbance excitation (diffuse sound field), the passive composite structure, the actuators (piezoceramic patch transducers) and sensors (accelerometers) as well as the fluid-structure interaction causing the sound radiation. A simulation of the system in the frequency domain yields a numerical performance prediction for a specific transducer configu-ration. A genetic search algorithm is used for the derivation of optimal positions for the selected actuators. The optimal number of sensors is determined by using the singular values of the cross-power spectral density matrix. All potential sensor positions are spanned by a fine sensor grid. The optimal placement is guided by a combination of the Observability Gramian and the superposed modal amplitudes weighted by their corresponding radiation efficiency. For the experiments, the active CFRP panel is mounted in an acoustic transmission loss test facility with a reverberant sending and a semi-anechoic receiving room. High-order system models are derived by the use of a multiple-reference test and subsequent system identification. Different con-trollers are designed and implemented on a rapid-control-prototyping system. The acoustic per-formance is evaluated by means of sound power measurements in the receiving room.