나선형 흡진기로 구성된 진동 메타물질을 이용한 방사 소음 저감 = Radiation Noise Reduction Using Vibrating Metamaterial Comprising a Spiral Absorber

다국어 초록 (Multilingual Abstract)

In this paper, we propose a vibration metamaterial that effectively reduces radiated noise and demonstrate its performance in reducing radiated noise through experiments. Using a spiral beam-shaped absorber as a unit cell, local vibration is generated in the target frequency band. The dispersion curve calculated using the plane wave expansion method is compared with the finite element analysis result, and the relationship between the band gap and the radiated noise reduction band is identified. The effects of the dimensions, mass, and resonant frequency of the spiral absorber on the band gap are investigated. Based on these results, a unit cell for reducing radiation noise generated by the first natural mode of the beam is designed. The validity of the design result is verified through the vibro-acoustic reciprocity-based experiment for the vibration metamaterial. The results of this study can be applied to the suppression of radiated noise generated outside by panel vibration by mounting it inside the panel surrounding the mechanical product.

국문 초록 (Abstract)

본 논문에서는, 목표 주파수 대역에서 방사 소음을 효과적으로 저감시키는 진동 메타물질을 제안하고 실험으로 방사 소음 저감 성능을 입증한다. 나선형 흡진기를 진동 메타물질의 단위체로 사용하여 목표 주파수 대역에서 국부적인 진동을 일으킨다. 평면파 확장법을 사용하여 계산된 분산 곡선은 유한요소 해석 결과와 비교하여 그 유효성을 확인하고, 밴드 갭과 방사 소음 저감 구간의 관계를 파악한다. 나선형 흡진기의 주요 치수 변화, 질량 변화, 공진 주파수 변화가 밴드 갭에 미치는 영향을 고찰한다. 이 결과를 바탕으로 보의 1차 고유 모드에 의해 발생하는 방사 소음을 저감시키기 위한 단위체를 설계한다. 이렇게 설계된 진동 메타물질에 대한 진동-음향 상반성 기반 실험을 통해 설계 결과의 유효성을 검증한다. 본 연구 결과는 기계 제품을 둘러싸는 패널의 내부에 장착하여 패널 진동에 의해 외부로 발생하는 방사 소음 억제를 위해 사용될 수 있다.

참고문헌 (Reference)

1 Wyckaert, K, "Vibro-Acoustical Modal Analysis: Reciprocity, Model Symmetry, and Model Validity" 100 (100): 3172-3181, 1996

2 Lee, S, "Vibro-Acoustic Metamaterial for Longitudinal Vibration Suppression in a Low Frequency Range" 144 : 223-234, 2018

3 Gürgöze, M, "On the Representation of a Cantilevered Beam Carrying a Tip Mass by an Equivalent Spring-Mass System" 282 (282): 538-542, 2005

4 Huang, H. H, "On the Negative Effective Mass Density in Acoustic Metamaterials" 47 (47): 610-617, 2009

5 Ewins, D. J, "Modal Testing: Theory, Practice and Application" Research Studies Press Ltd 2000

6 An, B. H, "Metamaterial-based Muffler with Broadband Tunability in a Lmited Space:Optimal Design, Theoretical Investigation and Experiment" 205 : 2021

7 Rao, S. S, "Mechanical Vibrations" Pearson 2011

8 Xiao, Y, "Longitudinal Wave Band Gaps in Metamaterial-based Elastic Rods Containing Multi-Degree-of-Freedom Resonators" 14 (14): 2012

9 Liu, Z, "Locally Resonant Sonic Materials" 289 (289): 1734-1736, 2000

10 Yu, D, "Flexural Vibration Band Gaps in Euler-Bernoulli Beams with Locally Resonant Structures with Two Degrees of Freedom" 73 (73): 2006

11 Yao, S, "Experimental Study on Negative Effective Mass in a 1D Mass-Spring System" 10 (10): 2008

12 Xiao, Y, "Broadband Locally Resonant Beams Containing Multiple Periodic Arrays of Attached Resonators" 376 (376): 1384-1390, 2012

13 Peng, H, "Acoustic Multi-Stopband Metamaterial Plates Design for Broadband Elastic Wave Absorption and Vibration Suppression" 103 : 104-114, 2015

14 Lee, S. H, "Acoustic Metamaterial with Negative Density" 373 (373): 4464-4469, 2009

15 Jung, J. W, "Acoustic Metamaterial Panel for Both Fluid Passage and Broadband Soundproofing in the Audible Frequency Range" 112 (112): 2018