Piezocomposite coating for active underwater sound reduction

Abstract

An active acoustic coating is presented for layering over objects in a fluid medium. The design of the active coating prevents an incident sound wave from reflecting off the acoustic boundary of a submerged object. The acoustic energy associated with the incident disturbance is absorbed out of the medium through a piezocomposite device in the coating and dissipated by internal electrical means. The components encapsulated inside the elastomer coating are a piezocomposite actuator and piezoelectric polymer sensors. The sensor arrangement detects and separates the acoustic field into a signal in terms of the incident acoustic pressure wave. The signal is manipulated through an electronic network to generate an appropriate driving voltage. This output drives a thickness extensional mode piezocomposite transducer (actuator) with a linear velocity profile over a broad frequency band. The actuator excitation results in a dynamic impedance matching with the incident disturbance such that the coating appears as a nonreflective acoustic surface. An advanced coating design includes an actuator that can be simultaneously driven to reduce the reflected and transmitted sound fields. Experimental results are presented for one-dimensional incident planar acoustic waves propagating in a water filled pulse tube.

Algorithm for Active Suppression of Radiation and Acoustical Scattering Fields by Some Physical Bodies in Liquids

“…This paper represents an attempt at solving the edge problem of active wave suppression under initial conditions. Such a problem statement (plus stable promotion of technological developments of very fast, very small and highly accurate elements of hard electronics) gave several new possibilities to find the solutions, more close to practice, if the conditions (18), (32) are fulfilled.…”

“…This represents two-layer plane segments [31][32][33][34][35] of a piezocomposite material. Longitudinal impedance and speed of propagation of longitudinal sound are the same for an active coating and the external fluid respectively [33,36,38].…”

A Transfer Matrix Approach for Acoustic Analysis of a Multilayered Active Acoustic Coating

“…The resulting signal is therefore a superposition of the two components. Therefore, the dual arrangement is preferred for separating the incident sound wave [23,24]. The dual sensor may be in other forms, such as one sensor layer for sound pressure and one accelerometer for particle velocity [10].…”

Low-Frequency Active Echo Reduction Using a Tile Projector

“…[ [1][2][3][4][5][6] 대표적으로 Howarth et al [1] 은 톤필츠 트랜스듀서와 1-3형 압전복합체 트랜 스듀서를 이용해 반사면에서 능동 임피던스 정합을 이룸으로써 반사파를 감소시키는 실험을 수행하였다.…”