Viscoelastic and acoustic characterization of polyurethane‐based acoustic absorber panels for underwater applications

Abstract

Acoustic absorbers that can have applications in a desired frequency band are a challenge often encountered in underwater acoustic absorber panel design. Polyurethane-based sound absorbing composite panels were designed with the help of finite element method (FEM) modeling using COMSOL for material formulations that can give optimum performance of echo reduction (ER) with minimum thickness. Polyurethanes of different compositions were evaluated for their acoustic performance using FEM modeling and experimental validation of the modeling results was done. The frequency-dependent modulus and damping properties were generated using dynamic mechanical analyzer and time-temperature superposition were performed to generate the material properties in the high frequency range (up to 25 kHz), which are significant for underwater acoustic detection applications and these data were used as inputs for modeling studies. Acoustic properties of the samples were experimentally evaluated using a water-filled pulse tube in 2-15 kHz frequency range as well as in an acoustic tank test facility for bigger dimension panels. These are nonresonant type absorbers capable to overcome limitations arising from environmental factors such as high hydrostatic pressures and also they are effective over a broad range of frequency (500 Hz-15 kHz) with ER > 15 dB.

Development and Applications of a Pressurized Water-Filled Impedance Tube

“…Determining the relationships between pore size, pore structure, and sound-absorbing performance can aid in the manufacturing of porous materials with a high sound-absorbing performance; however, the investigation of these relationships is beyond the scope of the present study. Additional information on underwater sound-absorbing materials can be obtained from the studies of Jayakumari et al [ 28 ], Guillermic et al [ 29 ], Dong and Tian [ 30 ], and Fu et al [ 18 ].…”

Polyurethane: Recent Engineering Contributions

“…With the finite element method PU sound absorbing panels were designed using for material formulation Comsol able to provide optimum performance of echo reduction with minimum thickness. The research shows that by judicious choice of matrix/ filler combination it is possible to achieve selective/broadband absorber for underwater applications [90]. Using Tung oleic acid-base polyol and polyether polyols a new biobased PU foam different from common PU foam was prepared.…”

Underwater metamaterial absorber with impedance-matched composite

“…Besides the experimental obstacles, designing an underwater absorber itself can be a challenge for theoretical modeling, because of the diversity of solid elastic vibration modes ( 32 ) that can give rise to difficulty in focusing on the absorption functionality absent of any undesired features. In addition, the acoustic energy density of the conventional materials ( 33 , 34 ) for underwater applications is relatively low, which hinders the efficient dissipation of the low-frequency waves within an acoustically thin sample. In other words, the potential of reducing the thickness of the underwater absorber has not yet been fully explored.…”