Effect of Vacuum Percentage on Sound Insulation of Composite Board

Due to the advantages of light weight, more and more carbon fiber materials are applied to different products such as automobile and train. The research on the sound insulation performance of carbon fiber panel has also become a key point. In this paper, the hollow seal composite board made of double-layer carbon fiber panel and air layer was taken as the research object and different ratio of the air was pumped to create different vacuum percentage. With the purpose of studying the relationship between the sound transmission lose (STL) and the vacuum percentage, the STL and the vibration of the composite panel were tested. The test results showed that the STL gradually decreased with the increase of vacuum, and the STL curves were shifted to the right mainly from 315 Hz to 1000 Hz. The reason is that both the reduction of the air damping effect and the increase of the vibration transmission efficiency of the composite board cause the reduction of sound insulation.