Impediment To Structure-Borne Sound Propagation Using Vibration Absorbers

The impediment to propagation of a flexural vibration wave in structures using vibration absorbers was studied. The power attenuation of the flexural vibration wave with the effect of the vibration absorbers was discussed in an infinite beam and an infinite strip.The formulae of transmission coefficient for an infinite beam and an infinite strip with an incident flexural wave and impeded by one and two vibration absorbers were derived respectively. The effects of the mass, the damping, the natural frequency and the number of the vibration absorbers on impediment to structure-borne sound propagation were discussed. For the infinite beam, the absorbers suppressing the vertical motion of the structures and the absorbers suppressing the rotation of the structures were used separately and then jointly. For the infinite strip, the power flow was introduced in defining the transmission coefficient of the flexural wave in the strip.The numerical computations in this paper were achieved by the mathematical software MATLAB. Numerical results show that the impeding effect of the vibration absorbers reveals strong selectivity on frequency. Either for the absorbers suppressing the vertical motion of the structures or for the absorbers suppressing the rotation of the structures, increase in mass is good for the impeding effect. Increase in damping weakens the maximum impeding effect, but it widens the frequency band of impediment and improves the frequency selectivity accordingly. For the same total mass, the impeding effect of multiple vibration absorbers is better than that of single vibration absorber. This paper provides a new method on the impediment to structure-borne sound propagation.