Judul: The Effect of Core Shape and Dimensions on the Physical and Mechanical Properties of Tali Bamboo Sandwich Panels
Abstrak: Bahan untuk produk mebel dan bangunan yang saat ini disukai adalah yang ringan tetapi kuat, salah satunya teknologi kayu komposit. Pengembangan material dengan struktur sandwich bertujuan untuk memperoleh material dengan bobot yang ringan dengan kekuatan serta kekakuan yang besar. Penelitian ini bertujuan mengetahui pengaruh bentuk core terhadap sifat fisis dan mekanis panel sandwich dari bambu tali serta mengetahui pengaruh dimensi core terhadap sifat fisis dan mekanis panel sandwich dari bambu tali. Pengukuran sifat fisis seperti kerapatan, kadar air, daya serap air, dan pengembangan tebal. Pengujian mekanisnya yaitu kuat tekan, MOR sejajar serat dan tegak lurus serat, MOE sejajar serat dan tegak lurus serat serta internal bond menggunakan UTM (Universal Testing Machine). Variasi dimensi contoh uji berukuran 3 cm, 4 cm, dan 5 cm, sedangkan variasi bentuk core yaitu heksagonal, persegi, dan segitiga. Berdasarkan data yang diperoleh dan analisis yang dilakukan, contoh uji terbaik memiliki core dengan dimensi sedang (4 cm) dan berbentuk segitiga., The currently preferred materials for furniture and building products are light but strong, one of which is composite wood technology. The development of materials with a sandwich structure aims to obtain materials with a light weight with great strength and stiffness. This research aims to determine the effect of core shape on the physical and mechanical properties of sandwich panels made of bamboo rope and to determine the influence of core dimensions on the physical and mechanical properties of sandwich panels made of bamboo rope. Measurement of physical properties such as density, water content, water absorption capacity, and thickness expansion. The mechanical tests are compressive strength, modulus of rupture parallel to the fiber and perpendicular to the fiber, modulus of elasticity parallel to the fiber and perpendicular to the fiber and internal bond using UTM (Universal Testing Machine). The variations in the dimensions of the test samples are 3 cm, 4 cm and 5 cm, while the variations in core shape are hexagonal, square and triangular. Based on the data obtained and the analysis carried out, the best test samples have cores with medium dimensions and a triangular shape.
Keyword: core dimensions, core shape, sandwich panels, tali bamboo

Judul: Characteristics of Physical and Mechanical Properties with Differences on the Thickness of Core and Skin from Tali Bamboo Sandwich Panels
Abstrak: Kebutuhan kayu yang semakin meningkat ditengah ketersediaannya yang terbatas saat ini, telah mendorong dibutuhkannya suatu bahan alternatif lain pengganti kayu yang memiliki kekuatan yang baik serta melimpah ketersediaannya. Bambu dapat menjadi salah satu alternatif bahan baku pengganti kayu yang dapat digunakan dengan potensi yang berlimpah. Penelitian ini bertujuan untuk menganalisis pengaruh ketebalan skin dan core terhadap sifat fisis dan mekanis panel sandwich bambu tali. Variabel yang diuji terdiri atas 6 variasi pasangan ukuran tebal skin dan core yang berukuran 1 mm dan 18 mm, 2 mm dan 16 mm, 3 mm dan 14 mm, 4 mm dan 12 mm, 5 mm dan 10 mm, serta 6 mm dan 8 mm. Perekat yang digunakan dalam pembuatan panel sandwich ini adalah polyvinyl acetate (PVAc). Pengujian contoh uji yang meliputi sifat fisis dan mekanis panel, masing-masing mengacu pada standar SNI 03-2105-2006. Sifat fisis yang diuji meliputi kadar air, kerapatan, pengembangan tebal, dan daya serap air. Sementara, pengujian sifat mekanis meliputi MOE, MOR, kuat tekan, dan keteguhan rekat. Hasil penelitian menunjukkan kualitas panel yang dibuat belum memenuhi syarat SNI 03-2105-2006 untuk papan partikel, kecuali kadar air dan pengembangan tebal. Panel sandwich tidak mengalami kerusakan baik pada bagian core maupun skin. Kerusakan terjadi pada ikatan garis rekat antar skin dan core. Penggunaan jenis perekat yang lebih kuat namun tetap ramah lingkungan diharapkan dapat memperbaiki karakter panel sandwich yang dihasilkan., The increasing need for wood amidst its current limited availability has prompted the need for an alternative substitute for wood that has good strength and is abundantly available. Bamboo is the one of alternative raw materials that can be used with abundant potential. This study aims to analyze the effect of skin and core thickness on the physical and mechanical properties of tali bamboo sandwich panels. The variables tested consisted of 6 variations of skin and core thickness pairs measuring 1 mm and 18 mm, 2 mm and 16 mm, 3 mm and 14 mm, 4 mm and 12 mm, 5 mm and 10 mm, as well as 6 mm and 8 mm. The adhesive used in making this sandwich panel was polyvinyl acetate (PVAc). The obtained panels were tested for their physical and mechanical properties by referring to the SNI 03-2105-2006 standard. The physical properties tested include water content, density, thickness expansion, and water absorption capacity. Meanwhile, mechanical properties testing includes MOE, MOR, compressive strength, and internal bond. Results revealed that the quality of the panels produced did not meet the SNI 03-2105-2006 requirements for particle board, except for moisture content and thickness swelling. The sandwich panel did not undergo damage to either the core or skin. Damage occurred at the bond line between the skin and core. The use of a stronger but still environmentally friendly type of adhesive is expected to improve the character of sandwich panels production.
Keyword: core thickness, polyvinyl acetate, sandwich panel, skin thickness, tali bamboo

Judul: A Continuous Vaccination Strategy in the SVIR Epidemic Model
Abstrak: Vaccination is conducted to minimize the spread of a disease. The vaccination is usually done several times within a fixed time interval. In the SVIR model, it is assumed that individuals do not get immediate immunity following a vaccination program. So according to process of vaccination on SVIR model, there are two strategies, i.e. the continuous vaccination strategy (CVS) and the pulse vaccination strategy (PVS). In this study, only the CVS strategy in epidemic model SVIR is considered. Results of the study indicate that dynamics of the CVS system depends on the basic reproductive number. If the basic reproductive number is less than one, then the disease-free fixed point is asymptotically stable. It means that the disease will eventually disappear from the population. Conversely, if the basic reproductive number is greater than one, then the endemic fixed point is asymptotically stable, which means that the disease will remain exist in the population. Simulation result shows that the vaccination would minimize the spread of disease by reducing the basic reproductive number. If the time for the vaccinated recipients to obtain the immunity, as well as a possibility of vaccinated recipients to be infected are neglected, then the disease will be eradicated. This condition is called an over-evaluating effect of vaccination.
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