What is the effect of the thickness of the GMT sheet on the sound absorption effect?
The thickness of the GMT board determines the magnitude and frequency range of the sound absorption coefficient. Increasing the thickness can increase the sound absorption coefficient, especially the middle and low frequency sound absorption coefficient. The figure below shows the sound absorption coefficient-frequency curve corresponding to the low, medium and high air permeability GMT automotive interior ceilings with thicknesses of 3, 4, and 5 mm. Among them, the lightweight GMT sheet used in the interior of the car interior has an areal density of 800g/m2.
As can be seen from the above figure, the forming thickness of the automotive interior ceiling has a great influence on the sound absorption coefficient, whether it is in the low frequency (0 ~ 2000Hz) section, the intermediate frequency (2000 ~ 4000Hz) section or the high frequency (4000 ~ 6000Hz) section , sound absorption The coefficient generally increases with the increase of the forming thickness because the expansion ratio of the GMT sheet increases as the forming thickness increases, so that the porosity of the sheet increases, thereby not only increasing the amount of sound waves but also causing sound waves. There is a longer propagation path in the plate, more sound waves are converted into heat energy during the friction and oscillation with the glass fiber, and the sound waves passing through the ceiling of the car interior are less, showing an increase in the sound absorption coefficient.
Therefore, increasing the forming thickness is a very effective means of increasing the sound absorption coefficient.