Active Vibration Control Applications Research Articles

Synthesis and Properties of Magnetorheological (MR) Fluids for Active Vibration Control

ABSTRACTMagnetorheological (MR) fluids represent an exciting class ofsmart materials for use in active vibration control and other applications. This paper discusses some of the fundamental materials science concepts that define the scientific basis for designing MR fluids. Preliminary experimental data and observations concerning the synthesis as well as the rheological behavior of MR fluids based on carbonyl iron and iron oxide particulates are presented and discussed.

Measurement of the modal shapes of inhomogeneous cantilevers using optical beam deflection

The study of free vibrations of systems such as simple cantilevers has been mainly concerned with the determination of the eigenvalues (frequencies) and eigenfunctions (modal shapes). A technique has been developed, using optical beam deflection, to measure the modal shape of a cantilever non-invasively at each modal frequency. A knowledge of the modal shapes of very small cantilevers incorporating suitable actuators is important in the application of active vibration control to micromechanical structures.

Smart Ceramics for Broadband Vibration Control

The broadband control of compliance coefficient S33 of a hard ceramic has direct applications in active vibration control. A collocated smart system consisting of ceramic sensor, actuator and a feedback amplifier is developed with 3.5 kHz bandwidth of compliance control without using filter in the feedback circuit. It is found that modified lead titanate with very low planar coupling coefficient kp is most suited as a sensor material for this type of system. The require ments of the feedback amplifier for such a system are discussed and an amplifier design presented. The bandwidth of compliance control is experimentally determined by bench tests using a B and K shaker.

Smart Ferroelectrics for Acoustic and Vibration Control

The dynamic compliance coefficient S33 of hard ceramic structures can be changed by incorporating them as sensor-actuator combinations and applying electronic feedback in proper phase. These smart ceramic structures can sense and react to pressure fluctuations by changing their compliance so that energy can be removed from the stimulus. Some basic geometries of smart struc tures in which there is negligible field coupling between the sensor and the actuator and a basic smart structure with very high field coupling are developed and their applications in active vibration control investigated. Results for narrowband vibration control are presented which clearly show that ceramic structures can be made harder or softer depending on the phase of the feedback signal.

Actuator for active vibration control

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