A distributed active vibration absorber for sound radiation and vibration control

Abstract

This paper discusses the analytical and experimental development of a distributed active vibration absorber (DAVA) designed to reduce sound radiation and vibration over extended areas of elastic structures. The distributed vibration absorber, in contrast to the classical vibration absorber, consists of a continuous active elastic layer covered with a continuous mass distribution. The distribution of the mass layer can be optimally designed to reduce either sound radiation or vibration over selected areas or frequency bands for particular structures. The paper first discusses an analytical model of the DAVA based upon variational techniques and used in conjunction with a genetic algorithm to design the mass distribution optimally. Simulated results on vibration and sound radiation control for a vibrating beam are presented and are compared to experimental realizations of the DAVA. The analytical and experimental tests confirm that the DAVA can passively attenuate vibration and sound radiation through an extended area and over an extended frequency range. The DAVA is shown to outperform the classical point vibration absorber significantly. The introduction of an active signal to the DAVA is seen to provide significant additional sound and vibration reduction. The DAVA is demonstrated to provide effective passive and active vibration and sound control in a conformal, compact, skin treatment. [Work funded by the ONR, Dr. Kam Ng, Technical Monitor.]