Analisis Kinerja Diffusorber Dekoratif Berlapis Serbuk Sabut Kelapa dengan Penambahan Rangkaian Helmholtz Resonator

Penelitian ini berfokus pada penambahan lapisan serbuk sabut kelapa dan penambahan rangkaian helmholtz resonator untuk meningkatkan koefisien serap bunyi pada diffusorber. Sampel diffusorber terbuat dari bola plastik yang berbentuk seperti telur dengan berbagai ukuran. Koefisien serap bunyi diuji dengan menggunakan tabung impedansi B&K 4206 dengan standar ASTM E-1050. Hasil yang diperoleh menunjukkan bahwa penambahan serbuk sabut kelapa meningkatkan koefisien serap bunyi tanpa terjadi pergeseran puncak penyerapan bunyi. Semakin besar volume diffusorber memiliki nilai koefisien serap semakin tinggi dan puncak penyerapan bunyi bergeser ke frekuensi lebih rendah dari sebelumnya. Penambahan rangkaian helmhotz resonator meningkatkan koefisien serap bunyi dan menyebabkan terjadinya pergeseran puncak koefisien serap bunyi. Perbedaan bentuk lubang pada permukaan diffusorber menyebabkan pola penyerapan yang berbeda-beda. Penambahan rongga pada bagian dalam diffusorber menyebabkan terjadinya puncak penyerapan bunyi yang baru

Kinerja Akustik dan Mekanik Panel Sandwich Berbasis Ampas Tebu dan Bambu

Telah dilakukan pengujian kinerja akustik dan kinerja mekanik panel sandwich berbasis ampas tebu dan bambu. Pengujian kinerja akustik dilakukan secara eksperimen mengacu pada prosedur ASTM E-1050-98dan kinerja mekanik menggunakan material testing machine. Pada penelitian ini dilakukan variasi ketebalan komposit ampas tebu dan pengaruh penambahan lapisan bambu di permukaan atas dan bawah komposit ampas tebu. Hasil penelitian menunjukkan bahwa pengaruh ketebalan sampel adalah menggeser penyerapan bunyi efektif pada frekuensi rendah sedangkan penambahan lapisan bambu pada komposit ampas tebu mempengaruhi penurunan nilai koefisien serapan bunyi yang dikarenakan tingkat kekerasan tinggi dan porositas rendah pada lapisan bambu. Adapun pengaruh ketebalan terhadap kinerja mekaniknya adalah menurunkan nilai MOR dan MOE sementara pengaruh penambahan lapisan bambu membuat nilai MOR naik dan nilai MOE turun. Pengaruh ketebalan dan penambahan lapisan bambu juga mengubah nilai densitas sampel.AbstractSound absorption performance and mechanical performance have been conducted in panel sandwich based bagasse and bamboo. The testing acoustic performance was conducted experimentally refer to ASTM E-1050-98 standard procedure and mechanical performance using a material testing machine. In this research, thickness variation bagasse composite and bamboo effect of adding a layer on the surface of the upper and lower composite bagasse. The results showed that the influence of the thickness of the sample is to shift the effective sound absorption at low frequencies while adding a layer of bamboo composite bagasse impairment affects the sound absorption coefficient due to a high degree of hardness and low porosity of the lining of bamboo. The effect of thickness on the mechanical performance is to lower the value of MOR and MOE while the effect of adding a layer of bamboo create value MOR MOE values rise and fall. The influence of the layer thickness and the addition of bamboo also change the value of the density of the sample

On the Sound Absorption Improvement of Water Hyacinth and Coconut Husk based Fiber Reinforced Polymer Panel

This paper emphasizes on the sound absorption improvement of the water hyacinth and coconut husk based fiber reinforced polymer (FRP) panel. The dry water hyacinth and coconut husk were milled and sieved before it mixed with polyester and methyl ethyl ketone peroxide as the catalyst. The composition is 200 ml, 25 grams, and 20 ml for the polyester, fiber, and catalyst respectively. The mixture casting is by using a square tray to form a flat FRP panel through open air drying without any compaction process. Three different approaches i.e. multiple quarter wavelength resonators, air cavity, and front fibrous layer inclusion are implemented to the FRP to improve its sound absorption performance. The entire measurements conducted by using transfer function based impedance tube technique refer to ASTM E-1050-98 standard. B&K 4206. It found that the proposed approaches are increase sound absorption coefficient of the bulk FRP significantly. The best performance occurred on the coconut husk based FRP when the 8 of quarter wavelength resonators combined with the fibrous layer. Sound absorption increased accordingly to above of 0.7 starting from 1.5 kHz. On the other side, the air cavity shows similar influence on the entire test sample due to Helmholtz resonance mechanism