Sensor—actuator tile for underwater surface impedance control studies

Abstract

An actuator—sensor tile has been developed for use in studies examining the issues involved in actively controlling the reflection and transmission characteristics of generic underwater structures. The tile is 25 cm square and contains a full area actuator, acoustic pressure sensor, and (acoustic particle) velocity sensor. This paper presents the predictive models used in the tile design. Issues addressed include transducer performance, spatial sampling, near-field sensing, internal resonances, and both direct and extraneous coupling mechanisms, all of which can contribute to complicate the system transfer functions. The acoustic characteristics of the final tile were evaluated at the NRL Laboratory for Structural Acoustics (LSA) and these results are compared with predictions.

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

“…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].…”

“…Photiadis et al [8] presented a simple centre-of-mass representation (SCMR) for a double-layer actuator, which can provide a direct view of the actuator operation. Furthermore, the authors extended this technique to study the in#uence of backing compliance on the performance of surface mounted actuator [9] and to predict the acoustic characteristics of each transducer component [10].…”

Hybrid vibration isolator: Single axis control study

“…The model used is the equivalent network model of Tims 12 as applied in previous studies. 13 Comparing these modeling results, the sensor material chosen was type PR-305 piezorubber ͑NTK Piezoelectric Ceramics Division, NGK Spark Plug Co.͒ This material is readily available with silver ink electrodes. The sensor consists of two 1.25 mm thick layers of this material, forming a 6.45 cm 2 area sensor.…”

Active sound control on boundary layers

“…GRP is used for both the sensor and the actuator to reduce the lateral strain and enhance the uniformity of thickness velocity and are also required in order to shield the actuator and sensors from electromagnetic interference. A thin metallic decoupling layer is put between the sensor layer and the damping layer as recommended by Corsaro et al [10] .…”

“…A stable control system can be developed since the difference between pressure signal and acoustic impedance times velocity signal serves as an error signal. Gentilman et al [8,9] and Corsaro et al [10] have been investigating the fabrication and packaging issues of such underwater acoustic impedance control titles.…”