Natural fibres as reinforcement of composite have been applied during the last decade. One of natural fibre has been used as reinforcement is coir fibre. As reinforcement of composite, such fibre needs treatment to improve compatibility with its matrix with suitable treatment. In this paper, surface treatment of such fibre was conducted using sodium bicarbonate (NaHCO3) solution with various densities and soaking time differences. Mechanical and morphological properties of coir fibre were investigated. Coir fibres were soaked in the 8 wt.%, 10 wt.%, and 12 wt.% sodium bicarbonate solution for 24 hours and 120 hours. After treatment, coir fibres were characterized with tensile testing, scanning electron microscope (SEM), Fourier transform infrared (FTIR) and x-ray diffraction (XRD). The results suggested that mechanical properties of coir fibre after sodium bicarbonate solution changed for all densities and soaking time. The coir fibre treated in 12 wt.% sodium bicarbonate for soaking time 120 hours has highest tensile strength. The surface morphology of fibre was analyzed by using SEM. It showed micropores on the fibre surface which may influence the mechanical properties of coir fibre.
This research presented the influence of treated coir fiber with sodium bicarbonate on wettability and interfacial shear strength (IFSS) of coir fiber-epoxy composite. Coir fibers were immersed in the solution of sodium bicarbonate with three different densities (8wt%, 10wt%, and 12wt %) for 24 hours and 120 hours. Epoxy resin was utilized as a matrix of composite. Wettability and IFSS of coir fiber-matrix adhesion were evaluated. Fiber wettability to the matrix was performed by measuring the droplet contact angle. In addition, the IFSS of coir fiber - epoxy matrix was investigated by pull out method. The surface morphology of interfacial bonding between fiber and matrix after pull out testing was evaluated by scanning electron microscopy (SEM). The results show that fiber surface wettability was influenced by sodium bicarbonate where the contact angle decrease after treatment. It suggests that good wetting of fiber and matrix. While the density of 12 wt% sodium bicarbonate for 120 hours possessed the highest interfacial shear strength of fiber-epoxy adhesion compared with other densities.
Water power is a type of power obtained from the force created by flowing water. Energy created from flowing water can be harnessed as a form of mechanical energy that can be utilized to generate electricity. Undershot water wheels have been extensively used to take advantage of the water flowing from rivers or waterfalls. This research was conducted by using water turbines with bowl-shaped blades made of iron and acrylic. The diameter of the turbines was 30 cm, and the diameter of the blades was 9 cm. Four, six, and eight blades were used in the three water turbines for this research. The blades were discharged and loaded to turn the turbine to generate force. The results of the study showed that the highest efficiency (η = 74.22%) was found in the six-blade turbine with a discharge of 0.01228 m 3 /s. It can be concluded that water turbines with bowl-shaped blades can be used as an alternative energy in small-scale electric generators.
Drag aerodinamika pada kendaraan disebabkan adanya tekanan rendah dan separasi aliran di bagian belakang, yang berdampak pada menurunnya kecepatan, meningkatnya penggunaan bahan bakar, dan turunnya efisiensi kendaraan. Blowing merupakan salah satu pilihan rekayasa kendali aktif aliran yang dapat diterapkan pada desain kendaraan yang dapat mengendalikan pembentukan separasi aliran dan berefek positif berupa pengurangan hambatan aerodinamis. Penelitian ini bertujuan menganalisis pengaruh penerapan blowing terhadap pola aliran, distribusi tekanan, dan hambatan aerodinamika yang bekerja pada bagian belakang model. Dengan bantuan CFD Fluent 6.3, model uji yang digunakan adalah model kendaraan dengan sudut kemiringan geometri depan (α) 35o dan rasio terhadap model Ahmed bodi original adalah 0.17 (1:6), yang dilengkapi dengan blowing dengan kecepatan 1.0 m/s. Hasil komputasi mengindikasikan bahwa penerapan blowing dapat mengurangi pembentukan wake dan menunda separasi aliran dan dapat meningkatkan koefisien tekanan minimum pada bagian belakang model kendaraan sebesar 24.690%. Pengurangan hambatan aerodinamika diperoleh sebesar 9.583%.
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