Analysis and measurement of a matched volume velocity sensor and uniform force actuator for active structural acoustic control

Abstract

This paper presents a theoretical and experimental study of the frequency response function of a matched volume velocity sensor and uniform force actuator for active structural acoustic control. The paper first reviews the design of a volume velocity sensor and uniform force actuator on a panel, using piezoelectric film with quadratic shaping of the electrodes. The frequency response function of a matched volume velocity sensor and uniform force actuator bonded on either sides of a panel is then studied in detail. This analysis shows that below 100 Hz the sensor-actuator response is controlled by the bending vibration of the panel and a good estimate of the volumetric component of the transverse vibration of the panel is achieved. At higher frequencies, however, the sensoractuator response is controlled by the in-plane longitudinal and shear vibration of the panel, which causes the real part of the frequency response function to be not strictly positive and to be characterized by large amplitudes at higher frequencies. These two phenomena are important since they limit the possibility of implementing a stable direct velocity feedback control system using these transducers.

Robust active sound radiation control of a piezo-laminated composite circular plate of arbitrary thickness based on the exact 3D elasticity model

“…[36][37][38][39]68,70 A fairly effective method in active suppression of low-frequency acoustic radiation for prediction of the first radiation mode magnitude is to use uniformly spread piezoelectric sensor materials which essentially respond to the velocity distribution associated with such radiation pattern. 37,38,40 Therefore, a single-input singleoutput (SISO) volume velocity control system 38,40,71 employing an integrated piezoceramic sensor layer collocated with a constantly distributed volume velocity (uniform force) piezoelectric actuator layer (see Figure 1(b)) can be advantageously configured to effectively reduce the total volume velocity vibration of the panel at such lowexcitation frequencies. 23,24,[37][38][39][40] The electric charge accessible through the closed-circuit electrodes of the sensor lamina may be determined by simple integration of z-component of electrical displacement upon the electrode surface area, 72 i.e.…”

“…37,38,40 Therefore, a single-input singleoutput (SISO) volume velocity control system 38,40,71 employing an integrated piezoceramic sensor layer collocated with a constantly distributed volume velocity (uniform force) piezoelectric actuator layer (see Figure 1(b)) can be advantageously configured to effectively reduce the total volume velocity vibration of the panel at such lowexcitation frequencies. 23,24,[37][38][39][40] The electric charge accessible through the closed-circuit electrodes of the sensor lamina may be determined by simple integration of z-component of electrical displacement upon the electrode surface area, 72 i.e.…”

“…Such matched distributed actuator/sensor pair configuration will be seen later (section 'System Identification and Controller Design') to primarily measure and excite the first radiation mode of the composite panel. [37][38][39][40] Also, the associated control system, which essentially reduces the total volume velocity, is then anticipated to attain decent mitigations in the low-frequency sound power radiation, while avoiding the control spillover effects. 4,23,40 Before outlining the control method, we shall briefly describe the basic elastoacoustic model 50,51 (i.e.…”

“…[37][38][39][40] Also, the associated control system, which essentially reduces the total volume velocity, is then anticipated to attain decent mitigations in the low-frequency sound power radiation, while avoiding the control spillover effects. 4,23,40 Before outlining the control method, we shall briefly describe the basic elastoacoustic model 50,51 (i.e. the governing equations for the piezo-laminated circular panel structure coupled with the surrounding fluid mediums) in the next two subsections.…”

“…24 In this control configuration, the total volume velocity that is known to have the largest contribution to the low-frequency acoustic power emission can effectively be cancelled. [37][38][39] Furthermore, the common problems frequently associated with the conventional spatially discrete sensors and actuators, such as the weight/volume/support requirements, line moment excitation effects, 8 observability/controllability problems, and control spillover effects, 4,40 are avoided.…”