NUMERICAL INVESTIGATION OF ACOUSTIC ISOLATION IN PERFORMANCE HALLS THROUGH COVERING WITH PHONONIC CRYSTALS

Öz

Sound isolation via covering walls with phononic crystal composed of periodic triangular wooden protrusions is demonstrated through numerical calculations. Sound isolation is achieved by surface modes of the phononic crystal. Band structure calculations through the Finite Element Method revealed a surface band with a maximum of 553 Hz when the periodicity, wall thickness and triangle apex angle are 25 cm, 15 mm and 60 degrees, respectively. Surface band the modes of which are localized in the flat regions between triangles covers the accord frequency at 440 Hz. Stationary Finite Element analyses demonstrate that plane waves with frequency between approximately 300 Hz and 550 Hz incident at small angles with the surface can be guided over the surface with low reflection and scattering. Guiding at 440 Hz can be achieved up to 30 degrees angle of incidence

Anahtar Kelimeler

• Acoustic isolation, Phononic crystal, surface mode

FONONİK KRİSTAL KAPLAMA İLE GÖSTERİ SALONLARINDA AKUSTİK YALITIMIN SAYISAL İNCELENMESİ

Öz

Periyodik üçgensel ahşap çıkıntılardan oluşan fononik kristal ile duvarların kaplanmasının ses yalıtımına katkı sağlayacağı sayısal hesaplarla gösterilmiştir. Ses yalıtımı fononik kristalin yüzey kipleri ile gerçekleştirilmektedir. Sonlu Elemanlar Yöntemi ile yürütülen band yapısı hesapları fononik kristal periyodu 25 cm, ahşap et kalınlığı 15 mm ve üçgen tepe açısı 60 derece iken tepe frekansı 553 Hz olan yüzey bandını göstermektedir. Yüzey kiplerinin üçgenler arasındaki düzlüklerde yerelleştiği yüzey bandı 440 Hz frekansındaki akort notasını kapsamaktadır. Durağan Sonlu Elemanlar analizleri yaklaşık olarak 300 Hz ile 550 Hz arasında yüzey ile küçük açılar yaparak gelen düzlem dalgaların az yansıma ile ve saçılmadan yüzeyde kılavuzlanabildiğini göstermiştir. Kılavuzlama 440 Hz frekansında 30 dereceye kadar olan geliş açılarında sağlanabilmektedir

Anahtar Kelimeler

• Akustik yalıtım, Fononik kristal, Yüzey kipi, Sonlu Elemanlar Yöntemi

Kaynakça

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