Active control of composite fuselage type structures with enclosed acoustic cavity

An active structural-acoustic control system for a composite fuselage type structure is developed in this paper. The focus of the active control system is the global reduction of the sound field in an enclosed acoustic cavity using structure-integrated sensors and actuators. Active structural-acoustic control systems are commonly designed based on the acoustic radiation modes which diagonalize a radiation operator. In the case of interior sound radiation, this radiation operator is derived in this paper from the coupled acoustic modes, which take into account the boundary conditions of the coupled velocity from the fuselage type structure. This results in frequency-independent radiation modes which do not rely on the validity of the modal interaction approach. The latter one violates the continuity condition of the velocity along the coupling surface. Parameter studies regarding active control implementations are conducted in order to evaluate how many radiation modes need to be considered for achieving a global sound attenuation.