ACTIVE CONTROL OF VIBRATION ENERGY TRANSMISSION IN AN INHOMOGENEOUSLY DAMPED PLATE

Abstract

The global attenuation of noise in an aircraft cabin for instance, is usually bound to the application of several sensors and actuators on the entire inner structure. However, if there are sharply localized noise and vibration sources in the overall system, the transfer paths from those to the radiating surfaces may be blocked actively. Therefore, by using structural intensity (SI) as a cost function for active control of transferred energy, previous studies show a benefit towards global attenuation of a downstream structure compared to conventional Active Vibration Control using a more centralized set-up of actuators and sensors. These approaches rely on the measurement of SI using finite differences by means of a simple Kirchhoff plate and the assumption of energy transfer mainly by flexural waves. However, these finite differences -approximating local derivatives of displacement- are prone to errors with increasing order of derivatives needed. Hence, a simplification of structural intensity measurement is needed, for the worse of accuracy. Preliminary numerical studies have shown a better attenuation performance than AVC even with simplified methods, especially for inhomogeneously damped structures. Hence, this paper presents the experimental studies on a damped rectangular plate using different sets of sensors and actuators to measure and control structural intensity. A feedforward approach is used for tonal and multi-tonal. Ultimately, the approach is compared to a simple velocity control.