Wave impedance characteristic analysis of composite wave impedance techniques

A wave dynamic response matrix method is proposed in this paper to investigate the problem of impeding structure-borne sound transmission from wave impedance facilities based on the wave approach, the impedance method, and the finite element idea. First, the structure is discretized into many wave elements and a general equilibrium equation of wave dynamic response is developed according to the displacement compatibility, force, and moment equilibrium at the junction node. Then, the wave dynamic response matrices of wave elements and the added wave dynamic response matrices of wave impedance facilities are deduced. The vibration amplitudes of wave elements are obtained by resolving the equilibrium equation, and the transmission efficiencies and transmission loss are then obtained. The method is then illustrated by a series of wave attenuation models such as blocking mass, elastic interlayer, and dynamic vibration absorber. Finally, numerical analysis focusing on the attenuation of structure-borne sound through the composite wave impedance facilities is conducted. The numerical simulation results show that the wave transmission loss within the full frequency domain is greatly reduced by using the composite wave impedance technique with a reasonable selection of design parameters and an optimal layout. The study provides certain guidance and a new control policy for the structural acoustic design of composite wave impedance facilities, which further offers guidance for the acoustic design of impedance techniques.