Research On Effect Of Filling Granular Material In Built-in Cavities On Sound Absorption And Sound Insulation Performance Of Sandwich Plate

The development of new acoustic structures and studies on the acoustic properties and influencing mechanisms of them has been a research hotspot in the field of noise control.This study proposed a sandwich plate structure with built-in cavities that were filled with granular materials,and then produced a series of samples with different aperture sizes of built-in cavities and different types of granular materials inside the cavities.The sound absorption coefficient and sound insulation of the samples were measured by the transfer function method and the four-sensor method,respectively.Then the differences in sound absorption and insulation performance between the sandwich plate structure proposed in this study and the homogeneous plate were compared.Moreover,the influence of the aperture sizes of built-in cavities and the types of granular materials inside the cavities on sound absorption and insulation performance was analyzed.Finally,COMSOL Multiphysics software was used to simulate the sound insulation performance of some samples.Results of this study are listed as follows.(1)Compared with the homogeneous plate,the peak sound absorption coefficient(sound absorption coefficient at resonance frequency)and the average sound absorption coefficient(mean value of sound absorption coefficients at all measured frequency points)of the sandwich plate with built-in cavities that were filled with granular materials were not improved.However,the width of the effective sound absorption band(sound absorption coefficient was greater than 0.2)of the structure was broadened by introducing additional sound absorption.The advantage is that the sound absorption performance indices such as the maximum sound absorption coefficient,resonance frequency,and effective sound absorption bandwidth of the structure can be adjusted by changing the parameters of the sandwich plate,such as changing the aperture sizes or changing the material types.(2)Compared with the homogeneous plate,the sound insulation performance of the sandwich plate structure was effectively improved by installing cavities in the plate body and filling the cavities with granular materials.When the other conditions vwere the same,the sound insulation at the first resonance frequency of the structure increased,and the average sound insulation(mean value of sound insulation at all measured frequency points)decreased.with the increase of the aperture sizes of built-in cavities.The sound insulation at the first resonance frequency of the structure increased as the densities of the fillincg materials in the cavities became larger.(3)The results of sound insulation simulation showed that there were differences between the simulation results and the measurement results,which may be because the boundary conditions of the measurement and the simulation calculation were not completely consistent,and the materials filled in the cavities were treated equivalently during the simulation calculation.However,the influence rule of the aperture sizes of built-in cavities and the types of granular materials inside the cavities on the sound insulation performance of the proposed sandwich plate obtained from these two methods was almost the same.