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All Journal Jurnal Teknologi Dirgantara
Nur M. Ula
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Aerospace Engineering Chemical Engineering, Chemistry & Bioengineering Computer Science & IT Mechanical Engineering Physics

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Frequency Mapping of Square Head Expander for Vibration Testing Mikhael Gilang Pribadi Putra Pratama; Muksin Muksin; Yusuf Giri Wijaya; Nur M. Ula; Agus Harno Nurdin Syah
Jurnal Teknologi Dirgantara Vol 20, No 1 (2022)
Publisher : National Institute of Aeronautics and Space - LAPAN

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30536/j.jtd.2022.v20.a3709

Abstract

Head expander is a component of an electro-dynamic shaker used for vibration tests in the vertical direction for large-size specimens. This study aims to determine the natural frequency distribution of the head expander across a certain number of predetermined points. This distribution map needs to be known to determine the better placement of future specimens on the head expander. In this study, the determination of natural frequency distribution is done through harmonic analysis (simulation) and experiment to form a contrast between the head expander's ideal condition and the actual condition. The frequency range in the middle of the Head Expander has almost the same value for both data types at 1550-1650 Hz. These results recommend that the best sample placement is in the middle of the Head Expander. The difference between the experimental and simulation low points has a not too far difference, which is 62.5 Hz. In contrast, at the highest value, the two have a quite far difference, which is 180.27 Hz. this difference can be caused by the improper installation of sensors on the Head Expander at certain points.
Investigation of the Mechanical Properties of Vinyl ester Carbon Composites Through Immersion in Seawater and Freshwater Using the VARI (Vacuum Assisted Resin Infusion) Method Nurul Lailatul Muzayadah; Taufiq S. Nurtiasto; Kosim Abdurrahman; Afid Nugroho; Nur M. Ula; Rezky Agung P.; Redha A. Ramadhan; Rozi Hendrawan
Jurnal Teknologi Dirgantara Vol 20, No 1 (2022)
Publisher : National Institute of Aeronautics and Space - LAPAN

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30536/j.jtd.2022.v20.a3579

Abstract

The carbon-vinyl ester composites have made for the development of the base material for Amphibious floats. The properties of this composite have strength, lighter weight and resistant to corrosion. This study was aimed to report the effect of two different water immersion treatment namely seawater and freshwater on the mechanical properties of composite made from fiber twill and vinyl ester resin using the vacuum assisted resin infusion (VARI) method. Experiments were carried out on tensile, compressive, and shear tests. The specimens were immersed in seawater and freshwater for ten days. The results have shown that Ultimate Tensile Strength of the composite with seawater immersion declined 1.27% compare with the composite without immersion treatment, while the composite in freshwater got greater 3.56%. The decrement of compressive and shear strength was more significant than tensile strength. The compressive strength declined 17.89% and 16.7% for freshwater and seawater treatment, respectively.  The shear strength decreased 27.87 % and 25.77% for freshwater and seawater treatment, respectively.
Co-Authors Afid Nugroho Agus Harno Nurdin Syah Kosim Abdurrahman Mikhael Gilang Pribadi Putra Pratama Nurul Lailatul Muzayadah Redha A. Ramadhan Rezky Agung P. Rozi Hendrawan Taufiq S. Nurtiasto Yusuf Giri Wijaya