Minimization of sound radiation from plates using adaptive tuned vibration absorbers

Vibration absorbers have widely been used to minimize the vibration of structures, either globally for rigid structures or locally for flexible structures. This paper presents novel experimental work by applying the use of vibration absorbers to minimize sound radiated by a simply supported plate. Experimental results are presented comparing the effectiveness of sound attenuation by an adaptive tuned vibration absorber (ATVA) using two different tuning algorithms. The first algorithm “tunes” the ATVA to the excitation frequency of the plate. The second control algorithm adapts the ATVA tuning frequency to minimize the radiated sound field. Results indicate that “tuning” the ATVA to the excitation frequency can guarantee reduction of the vibration level near the base of the ATVA, but cannot guarantee reduction of the radiated sound field. In fact, it is shown that “tuning” the ATVA can actually increase the sound levels. Using an acoustic cost function to optimize the resonant frequency of the ATVA is a more effective procedure to guarantee a reduction of the radiated sound field. As a result of using this cost function, the ATVA was “detuned”, i.e., the resonant frequency of the ATVA was not equal to the excitation frequency.