On the improvement measures of interior noise reduction of minivan’s roof based on acoustic modal analysis

Abstract

In this work, three types of measures, i.e., 1) adding the damping adhesive, 2) changing the local beads and 3) utilizing the dynamic vibration absorber (DVA), are performed to investigate and improve the acoustic quality of the minivan's interior noise. For adding the damping adhesive, the difference of the adhesive location directly affects the mode of minivan's roof. For changing the local beads, eight cases of beads are selected. The results indicate that the change trend of the first natural frequency is parabolic as the number of beads increases. For adding the 33 Hz DVA, the results show that the sound pressure levels (SPLs) of the minivan's response points located at the front, middle and rear seat in the critical frequency are approximately reduced by 2.1 dB, 1.5 dB and 1.1 dB in the minivan's simulation, and by 2.6 dB(A), 1.4 dB(A) and 2.7 dB(A) in the minivan's road experiment, respectively. By contrast, the DVA with a certain frequency should be chosen if the reduction of sound pressure level (SPL) is only considered. Furthermore, if the SPL's reduction and the additional mass are taken into account at the same time, the measure with local flatted beads should be selected. The obtained results could provide a certain practical guiding significance for improving the mode and interior noise of minivan's roof.