Numerical Analysis of Active Vibro-Acoustic Control in an Enclosed Cavity

A numerical model is applied to study the application of active vibro-acoustic control in an enclosed cavity. The vibro-acoustic problem is composed of a free-free beam, representing the windshield, coupled with a rectangular planar acoustic cavity, representing the passenger compartment. Forces at the windshield boundaries are actively applied to reduce noise due to floor panel vibrations and sound from a monopole source. Noise transfer functions are used to calculate the control forces based on their ability to minimize the acoustic energy distribution in the total region and within the region of interest. Results show that noise is substantially reduced in the low frequency range accompanied with some reduction at the higher frequencies as well. Results also show that applied forces based on partial area control have more potential in reducing noise within the region of interest than those based on global area control. It was also observed that this control strategy performs better in vibration induced noise problems than in monopole source problems. The proposed model can be applied to noise control problems involving the transmission of vibratory energy into a cavity through fluid-structural coupling that relates structural vibration to cavity acoustics.