Combination of Acoustic Black Holes with point masses

Abstract

Passive acoustic measures are suitable for the targeted improvement of the vibration behaviour of technical products. In this context, Acoustic Black Holes (ABH) as innovative measures have shown great effect for an efficient damping of vibrations and a simultaneous mass reduction. The vibration reducing effect, however, is primarily apparent in the higher frequency range. The thickness reduction results in a mass reduction of the system, which could worsen the vibroacoustic behaviour in the lower frequency range. The idea of the approach here is to use the saved material in form of point masses to counteract this disadvantage at low frequencies by a targeted placement or direct consideration in the manufacturing process. The result is a mass-neutral acoustic design measure. In order to investigate the effectiveness of the ABH point mass combination, finite element models of generic beam and plate structures with ABH are used in this paper. In addition, the influence of point masses in terms of their position and number on the vibroacoustic behaviour is simulated. One focus is the assessment of the advantage by combining ABH with point masses. To validate the results, experimental investigations are carried out and compared with the numerical results.