This research applies a numerical study of topology optimization of laminate composite structures by using a finite element method (FEM). In this methodology, the plies orientation is excluded from the optimization. The geometry-based optimization from frames of a MALE UAV fuselage structure is presented. The minimum strain energy with an optimization constraint of 20% of weight reduction is used in the objective function. Before the primary analysis, benchmark studies of topology optimization without considering orientations from previously published literature are performed. The convergence studies were taken to acquire the appropriate mesh size in the FEM technique, which utilized a four-noded shell element. The finite element analysis and optimization results showed that the structural design of the newly framed composite fuselage MALE UAV meets the structural strength requirements specified in the airworthiness standard STANAG 4671.
The rocket nozzle is a crucial and complicated part of a rocket, primarily for rocket RX320. Its function is to control the exhaust flow, so the rocket gets the maximum possible forward thrust. However, graphite materials are used inside rockets due to good mechanical properties and high melting temperature resistance. This study discussed the effect of post-static rocket fire testing on the mechanical properties of graphite materials and compared them with the technical data sheet (TDS) of its graphite. Mechanical properties testing has been done to determine the average flexural strength value with the flexural test method and the average value of the compressive test. The graphite has an average flexural test value of 40.185 MPa, with an average elastic modulus of 0.656 GPa. Furthermore, the average compressive test of graphite has a value of 67.71 MPa, with an average load of 1,560 N. The mechanical properties trends are slightly decreasing due to post static fire testing compared to TDS. It was around 41.2% for flexural strength and 50.7% for compressive strength.
In order to know about vibration characteristics of a combination between engine and propeller used in LAPAN Surveillance UAV (LSU) series, it needs a test apparatus called the engine vibration test stand. The engine vibration test stand structure must be strong and stiff to get good result in engine vibration test. In the initial phase, the engine vibration test stand was made of 1 meter length of ASTM A36 material with H shape and the lower part of it was bolted to the reinforced floor.By using a finite element method software and inputting some parameters from engine DA-170 and mechanical properties of ASTM A36, the engine vibration test stand had safety factor of 26,24.Furthermore, the top five natural frequencies were 61,94 Hz, 77,18 Hz, 93,79 Hz, 212,23 Hz and 286,24 Hz.
Penggunaan ply drop-off telah banyak digunakan untuk mengoptimalkan struktur komposit sehingga memiliki massa yang lebih ringan dibandingkan dengan struktur komposit dengan penggunaan ketebalan seragam. Tulisan ini akan memprediksi kekuatan dan potensi pengurangan massa struktur komposit dengan menggunakan ply drop-off pada roda pendarat utama pesawat nir awak terhadap beban operasional menggunakan metode elemen hingga. Beban operasional diasumsikan merupakan beban statik akibat landing sebesar 245 N arah vertikal dan sebesar 78.75 N arah horizontal. Struktur roda pendarat utama dimodelkan menggunakan elemen Quad4 dengan memasukkan sifat mekanis dari material e-glass Woven Roving 185 pada software MSC. Patran/Nastran. Kriteria kegagalan yang digunakan adalah berdasarkan kriteria kegagalan Tsai-Wu dalam indeks kegagalan dan margin of safety. Hasil yang didapatkan adalah struktur roda pendarat utama memiliki indeks kegagalan 0.62 dan margin of safety sebesar 1.39. Dari hasil tersebut menandakan struktur roda pendarat utama cukup kuat dan tidak terjadi kegagalan dalam menerima beban operasional yang diberikan. Di samping itu, potensi pengurangan massa pada struktur roda pendarat utama menggunakan ply drop-off adalah sebesar 18%.
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