A bending stiffness criterion for sandwich panels with high sound insulation and its realization through low specific modulus layers. (13th October 2022)

• Record Type: Journal Article
• Authors: Kang, Ludi; Sun, Chengpu; An, Fengyan; Liu, Bilong
• Is Part Of: Journal of sound and vibration. Volume 536(2022)
• Publication Date: 2022-10-13
• Subjects: Sandwich panel -- Sound transmission -- Bending stiffness -- Vibro-acoustics; Sound -- Periodicals; Vibration -- Periodicals; Son -- Périodiques; Vibration -- Périodiques; Sound; Vibration; Periodicals; Electronic journals; 620.205
• DOI: 10.1016/j.jsv.2022.117149
• Languages: English
• ISSNs: 0022-460X

Abstract

Abstract: The sound transmission loss of a sandwich panel is usually much lower than that given by the mass law for a homogeneous panel with the same weight in the mass-controlled frequency range. How to make the sound transmission loss of the sandwich panel close to the mass law and maintain a high static stiffness is a key acoustic issue in its design. In this paper, the critical apparent bending stiffness is defined as the apparent bending stiffness at which the sound transmission loss of a sandwich panel approaches that of the mass law. Then, a method is given to determine the critical apparent bending stiffness of sandwich panels, based on which a range of structural parameters can be obtained to guide the design of sandwich panels with high acoustic performance. Compared with the apparent bending stiffness of a typical sandwich panel, the critical apparent bending stiffness decays more rapidly with the increase of frequency, exhibiting a relatively high static stiffness and a relatively low dynamic stiffness. In order to make the apparent bending stiffness of a typical sandwich panel close to the critical apparent bending stiffness, the concept of introducing an elastic layer with low specific modulus in the middle of the core layer is proposed. Both theoretical and experimental results show that the introduced elastic layer with low specific modulus reduces the dynamic bending stiffness of the sandwich panel while a high static bending stiffness is maintained, thus significantly improving the broadband sound-insulation performance of the panel. Highlights: A criterion for designing sandwich panels with high transmission loss is proposed. An idea of introducing an additional layer with low specific modulus is proposed. The idea reduces dynamic bending stiffness while keeping high static stiffness. The idea is verified through predictions and tests for hand-made beams and panels.