Sound insulation performance and modal analysis of asymmetrical insulating laminated glass

Abstract

Windows are commonly the primary way for noise to enter the building environment. Most windows achieve higher sound insulation targets by simply increasing glass thickness or laminate. However, the glass thickness cannot be increased freely due to the window frame’s limitation. This research selects eleven kinds of asymmetric insulating laminated glass (glass + polyvinyl butyral + glass + air + glass) within 27 mm, which are the typical thicknesses of window frames. The three pieces of glass have equal thicknesses. The half-space acoustics method investigated the acoustic properties and modal behavior of the glass with finite thickness. The results show that when PVB or three glass increases simultaneously, and the sound insulation of each glass can be improved by 0.9∼3.4 dB or 3.7∼21.8 dB at first resonant frequencies, respectively. The glass with the best sound insulation is 7 mm glass + 0.76 mm polyvinyl butyral + 7 mm glass + 5 mm air + 7 mm glass (7 + 0.76 + 7 + 5A + 7 for short). Its sound transmission loss (TL) is 38.5 dB from 125 to 4000 Hz and 16.8 dB in the first resonant frequency (200 Hz). In addition, its first resonant frequency is the highest among eleven kinds of glass, and the number of natural frequencies in the low frequency range is only 9. These findings can provide a basis for designing asymmetric insulating laminated glass to improve the low frequency noise reduction effect effectively.