Uporaba vibroakustičnih metamaterialov v strukturni dinamiki za nižanje ravni hrupa

Košir, Tilen (author), Slavič, Janko (mentor), Boltežar, Miha (co-mentor)

V delu je predstavljena uporaba metamaterialov za namene zniževanja hrupa na področju akustike in strukturne dinamike. Preko obravnave osnovnega gradnika oz. bazne celice, ki sestoji iz osnovne strukture in resonatorja, so obravnavane lastnosti neskončnega 2D periodičnega metamateriala. Ob pravilni zasnovi je le-ta sposoben formirati pasovno zavrnitveni filter (PZF) v željenem frekvenčnem območju, kjer prosto širjenje valovanj ni dovoljeno. PZF smo identificirali s pomočjo disperzijskih krivulj, ki smo jih izračunali z uporabo direktnega in inverznega pristopa. Preračunan koncept metamateriala se je kasneje tudi izdelal s pomočjo FFF tehnike 3D tiskanja. Izračunano in izmerjeno frekvenčno območje PZF se zadovoljivo ujemata. Ob masnem razmerju resonatorja in osnovne strukture 0.1 je metamaterial v območju PZF zmožen hrup znižati za 4 dB več kot le njegova osnovna struktura ekvivalentne mase.

• Language: Slovenian
• Keywords: metamaterial, pasovno zavrnitveni, hrup, vibroakustika, Blochov teorem, periodične strukture, strukturna dinamika, metoda končnih elementov
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FS - Faculty of Mechanical Engineering
• Place of publishing: Ljubljana
• Publisher: [T. Košir]
• Year: 2020
• Number of pages: XXIV, 62 str.
• PID: 20.500.12556/RUL-118610
• UDC: 519.61:534(043.2)
• COBISS.SI-ID: 27796995
• Publication date in RUL: 28.08.2020

Secondary language

• Language: English
• Title: Vibroacoustic metamaterials for noise reduction in structural dynamics

Abstract

This thesis describes metamaterials for noise reduction in acoustics and structural dynamics. Through analysis of the unit cell of a 2D periodic metamaterial consisting of the base structure and carefully placed resonating structures, the dynamic characteristics of the whole structure were obtained via dispersion curves. Appropriately sized metamaterials can exhibit band gaps in which free wave propagation is not allowed. Band gaps were identified via dispersion curves which were calculated using a direct and inverse approach. Metamaterial design was also manufactured using FFF 3D printing technique. A good agreement between calculated and measured band gap frequency region was identified. 4 dB stronger noise reduction was measured by metamaterial with a mass ratio of 0.1 between resonators and base structure compared to only its base structure with equivalent mass.

• Keywords: metamaterial, band gap, noise, vibroacoustics, Bloch theorem, periodic structures, structural dynamics, finite element method