Verification of acoustic superiority of MDI-based gradient structural material on high water pressure

Abstract

Considering the limitation on high water pressure resistance of traditional underwater acoustic material, an optimization on material structure is conducted so as to improve the ability of sound absorption. Monolayer Acoustic Samples (MAS) and Gradient Acoustic Sample (GAS) are produced with the raw materials, such as diphenylmethane diisocyanate(MDI) polyurethane prepolymer(PUP) and butylene glycol (BDO). The samples are tested in the frequency range from 1000Hz to 4000Hz under pressure from 0 MPa to 2MPa. Then the differences of acoustic performance between MAS and GAS are analyzed and compared. The tests results show that the stability of GAS sound absorption coefficient increases gradually with the increasing of frequency under various pressures and the value of GAS sound absorption coefficient tends to be 1 in high frequency range. On the other hand, the value of MAS sound absorption coefficient fluctuates obviously. Compared with average sound absorption coefficient of two samples at 1000Hz, 2000Hz and 4000Hz, the GAS has a better sound absorption performance than the MAS.