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Developed countries are currently developing unmanned aerial vehicles (UAV), and the ability to fly these aircraft is still limited, especially in terms of distance and length of the flight. This capability can be increased by various technological developments, one of which is reducing the weight of the aircraft body by using lightweight and strong materials. So that the aircraft becomes lighter and stronger so that can reach longer distances, the material can use a polymer composite formed from polymer resin with carbon fiber reinforcement. This polymer composite material has been used in several parts of commercial aircraft and has even been used in fighter aircraft.t. This study aims to determine how much influence the curing time and type of carbon fiber composite forming process have on the mechanical strength and to observe the microstructure of the carbon fiber bond with the resin in its formation. The results of the mechanical characterization by means of a tensile test with the ASTM 3039 standard showed that the difference in curing time had no significant effect on the mechanical strength, whereas the curing time of 2 hours showed the highest strength. The difference in the process of forming these composites shows that the mechanical strength of the composite formed by VARI (Vacuum Assisted Resin Infusion) shows a high value, which is around 501 MPa, while the carbon fiber composite formed by the manual method, hand layup has a strength of only up to 288 MPa. From the observation of the microstructure of the carbon fiber composites, it can be seen that the carbon fiber composites formed by the VARI method have very good, compact, uniform, and non-porous surfaces. [ABSTRACT FROM AUTHOR]

Aircraft material usually uses light and strong metal alloys. This type of material will be damaged quickly when used in the marine environment, one of which is caused by corrosion which can erode the aircraft's structure. Therefore, a replacement material is needed for winged ships with the criteria of being a strong and light material, having a specific thickness, and being resistant to corrosion. Sandwich composite materials consisting of epoxy and woven roving E-glass fiber as the facing layer and polyurethane foam as the core material have been investigated. The materials with four types of panels having different fiber geometrical orientations of the facing were fabricated using vacuum assisted resin infusion (VARI) method. Tensile and flexural tests were performed on the materials to understand their mechanical properties and failure mechanisms. The resulting mechanical properties were best obtained from the panel facing having four layers of fiber orientation of 0°, 90°, +45°, -45° with tensile and flexural strengths of 28.18 and 5.75 MPa, respectively. Scanning Electron Microscope (SEM) examination was subsequently performed and showed that the failure of the materials started from the core and propagated to the facing layer. [ABSTRACT FROM AUTHOR]

Limited and expensive land aqusitions require the development of buildings in city areas that are built vertically upwards. So that the building structure is designed to be able to accommodate the loads that work on the building. In addition to the strength of the structure, the building must also fulfill the stiffness requirements. This work studied the effect of the use of Fixed Base and Base Isolation supports in highrise building structures. The calculation of earthquake loads used is based on the Response Spectrum Design of the earthquake in the South Jakarta area. The numerical simulation of the combined dead load, live load and earthquake load was carried out using the finite element based design tool, Etabs version 17. The lateral earthquake load was calculated using the static equivalent load principle. The number of floor of the building studied is 40 floors with a total height of 141 m. The results showed a decrease in shear forces and moments in buildings using Base Isolation was encountered in this study. Likewise on the top floor there is a decrease in the relative lateral drift between adjacent floors in buildings that use the base isolation. [ABSTRACT FROM AUTHOR]