Design optimization of a cellular-type noise insulation panel to improve transmission loss at low frequency

Abstract

In this paper, a systematic design method is proposed to improve the sound transmission loss of a cellular-type noise insulation panel, which is a thin rectangular plate with supporting frame. The unit cell of the noise insulation panel generates an anti-resonance effect at a certain frequency and yields a higher sound transmission loss than a flat plate of equivalent mass. Previous studies confirm that the mass ratio between the thin plate and the supporting frame has an important influence on the frequency at which the maximum sound transmission loss occurs. However, no design method to maximize the sound transmission loss at a target frequency has yet been reported, although this issue is very important for noise insulation of mechanical systems. In this regard, sizing optimization is performed using the thickness of the noise insulation panel as a design parameter. Hence, the optimal thickness distribution to maximize the sound transmission loss at a given target frequency is determined. To calculate the sound transmission loss, a finite element model of the noise insulation panel is constructed, considering the vibro-acoustic effect. Several numerical examples are presented to verify the proposed design method. The optimization results confirm that the designed unit cell exhibits high sound transmission loss at given frequencies of interest.