The Study Of The Theory For A New Functional Type Of Underwater Sound Absorption Coating

The underwater anechoic coating is the main equipment enhancing submarine' s concealing ability, and its anechoic materials must have the high absorbability and low reflection in order to eliminate the sound wave. Traditionally anechoic coating eliminates sound wave by using the single cylinder cavity resonance construct, but its frequency width is narrow. Now most sound absorption layers are impedance transition constructs, which have been used widely, but their thickness is limit and cannot meet the need of absorbing sound at low frequency. Nowadays underwater anechoic coatings are developing at low frequency, broad band, damping of vibration and sound insulation. In recent years, many countries' scholars pay more attentions to study sound absorption by using the piezoelectric effect of a piezoelectric composite in order to absorbing sound at low frequency and broad band. The investigation on both theory and experiment has just now begun. Therefore, in this thesis the emphasis of research is the theory of sound absorption, on the same time we simply carry through the experiment.In this thesis piezoelectric composites are simply introduced. 0-3 piezoelectric composites, 1-3 piezoelectric composites and 3-3 piezoelectric composites are introduced in detail. For the new functional type of underwater sound absorption coating, it helps us to study the theory and the analysis of model after the parameter' s model of piezoelectric composites is introduced.Firstly, in this thesis the theory of sound absorption of a piezoelectric composite (shortened form is piezorubber) consisting of the piezoelectric ceramic and the rubber is investigated. Secondly,...