Elucidation of innovative sound absorption mechanism with lightweight and fine powder

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04359
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 20010:Mechanics and mechatronics-related
• Research Institution: Niigata University
• Principal Investigator: Sakamoto Shuichi 新潟大学, 自然科学系, 准教授 (40211932)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 軽量な粉体 / 微細な粉体 / 粒状体 / 吸音率

Outline of Final Research Achievements

We proposed a noise control method focusing on lightweight powders. Specifically, we theoretically clarified how the effects of sound absorption by lightweight powders, which propagate sound waves by longitudinal vibration like gas molecules, are superimposed on those of sound absorption by vibration of the powder and sound absorption by gaps between particles. We searched for the conditions for powders in which this special sound absorption effect appears.
A mathematical model for the sound absorption of granular and flaky biomass materials, which are smaller than the wavelength of sound waves, was presented. A mathematical model was developed for the sound absorption characteristics of regularly arranged granular materials. Theoretical calculations for randomly arranged and irregularly shaped granular materials were performed based on geometric data measured by micro CT scans.

Free Research Field

機械音響工学

Academic Significance and Societal Importance of the Research Achievements

吸音材料は同じ性能であれば、軽く薄く安価である事が求められる。粉体は一般に生産性・輸送性が良く、形状が自在に変わるため異形部分への設置が容易という工学的利点がある。
提案する粉体による吸音方法では、軽量な粉体であり気体より重い程度の粉体が音響媒質となるため、縦波速度が劇的に遅くなり、吸音材料の厚さを遙かに薄くできる。
現状を打開するため、今まで用いられてこなかったこのような原理による吸音方法を実験的・理論的に示すことが本研究の目的である。