Sound Transmission Loss Enhancement in an Inorganic-Organic Laminated Wall Panel Using Multifunctional Low-Density Nanoporous Polyurea Aerogels: Experiment and Modeling


Recently, the authors have reported an exceptional normal incidence sound transmission loss characteristic for a class of low density, highly porous, and mechanically strong polyurea aerogels. Herein, a laminated composite comprising the organic low-density aerogels bonded with an inorganic compound (e.g., gypsum materials) is considered to investigate the constrained damping effects of the aerogels on the airborne sound insulation behavior of the composite using the standard chamber-based diffuse sound field measurements. Huge improvement in the sound transmission loss is obtained due to the use of aerogel without a significant increase in the overall weight and thickness of the composite panel (e.g., more than 10 dB increase by reaching 40 dB sound transmission loss at 2 kHz after the implementation of only two 5 mm-thick aerogel layers at bulk densities 0.15 and 0.25 g cm-3). This uncommon behavior breaks the empirical "Mass Law" nature of the most conventional acoustic materials. In addition, an exact analytical time-harmonic plane-strain solution for the diffused wave propagation through the multilayered structure is provided using theories of linear elasticity and Biot's dynamic poroelasticity. The theoretical results are well supported by the experiments which can be utilized for the design of the future light-weight multifunctional composite structures.




The support by AFOSR FA9550-14-1-0227, NSF CMMI-1636306, CMMI-1661246, and ECCS-1307997, and Nashi New Materials, Inc. China is acknowledged. N. L. and C. S.-L. thank the Army Research Office for financial support under Award Number W911NF-14-1-0369

Keywords and Phrases

Biot's poroelasticity; composite structures; diffuse field sound transmission loss; nanoporous materials; polyurea aerogel

International Standard Serial Number (ISSN)

1438-1656; 1527-2648

Document Type

Article - Journal

Document Version


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© 2018 Wiley-VCH Verlag, All rights reserved.

Publication Date

01 Jun 2018