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Ditemukan: 5 dokumenTOPOLOGY OPTIMIZATION OF TRIPLY PERIODIC MINIMAL SURFACE STRUCTURES FOR HYDROGEN STORAGE APPLICATIONS
Hydrogen energy storage is a cornerstone of the transition toward sustainable and renewable energy systems, requiring innovative solutions for efficiency and scalability. This research explored the application of Triply Periodic Minimal Surfaces (TPMS) structures, focusing on topology optimization to enhance mechanical integrity, internal volume and material efficiency under high loading conditions. For this study, a gyroid-based TPMS structure was integrated into a storage container geometry and optimized using the Solid Isotropic Material with Penalization (SIMP) method under displacement restraint, internal pressure, and external compressive loading. Both non-optimized and optimized structures were then put through static analysis to evaluate the structural response. The optimization process demonstrated stable convergence across all loading cases, resulting in redistributed material aligned with critical load-paths, with post-optimization analysis indicating increased structural compliance and localized stress concentrations, with a modest increase in internal volume. The results display that topology optimization enhances structural efficiency primarily through material redistribution rather than uniform material reduction, highlighting its potential for improving TPMS-based hydrogen storage structures.
PENINGKATAN FREKUENSI PRIBADI PERTAMA KANTILEVER MENGGUNAKAN PEGAS PENYANGGA MELALUI SIMULASI DAN PENGUJIAN FRF
Peningkatan frekuensi pribadi merupakan cara efektif untuk mencegah resonansi yang dapat merusak struktur seperti kantilever. Resonansi juga kerap terjadi pada mesin rotasi di mana frekuensi putar yang meningkat secara bertahap dapat mengeksitasi di berbagai frekuensi. Salah satu metode yang dapat diterapkan adalah dengan menambahkan pegas penyangga. Penelitian ini bertujuan untuk menentukan posisi optimal dan kekakuan pegas yang efektif dalam meningkatkan frekuensi pribadi pertama kantilever melalui simulasi modal dan pengujian eksperimental fungsi respons frekuensi (FRF). Penelitian ini mencakup optimasi konfigurasi pegas berdasarkan literatur, pemodelan kantilever menggunakan ANSYS, serta simulasi modal dengan metode elemen hingga. Selain itu, dilakukan pengujian FRF secara eksperimental menggunakan palu impak dan sensor akselerometer pada bahan uji, serta simulasi FRF untuk membandingkan hasil eksperimen dan simulasi. Hasil penelitian menunjukkan bahwa posisi optimal pegas penyangga berada di ujung bebas kantilever dengan kekakuan sebesar 12,94 N/mm. Pengujian FRF mengonfirmasi adanya peningkatan frekuensi pribadi, meskipun nilai yang diperoleh masih lebih rendah dibandingkan hasil simulasi. Penambahan kekakuan pegas terbukti efektif hingga batas tertentu, setelahnya perubahan modus getar membatasi peningkatan frekuensi lebih lanjut.
DESAIN DAN OPTIMASI MULTI-OBJEKTIF PANEL SANDWICH HONEYCOMB AUXETIC UNTUK STRUKTUR LAIK-LEDAK
Studi ini melakukan desain dan optimisasi multi-objektif dari auxetic hon- eycomb sandwich panels (AHSPs) yang terkena beban ledakan udara untuk meningkatkan kelaik-ledakan struktur kendaraan lapis baja. Metrik objektif yang digunakan sebagai parameter kelaik-ledakan adalah perpindahan permanen dan penyerapan energi spesik. Empat geometri auxetic diusulkan sebagai inti sandwich: re-entrant honeycomb (REH), double-arrow honeycomb (DAH), star honeycomb (SH), dan tetra-chiral honeycomb (CH). Setiap geometri dievaluasi potensinya untuk meningkatkan penyerapan energi dan meminimalkan deformasi dalam menerima ledakan. Kombinasi simulasi elemen hingga dan metodologi pembelajaran mesin digunakan untuk menilai kelaik-ledakan dari berbagai geometri AHSP. Optimisasi multi-objektif dilakukan menggunakan metode non-dominated sorting genetic algorithm II (NSGA-II) berdasarkan metamodel jaringan saraf tiruan. Pareto front dari hasil optimisasi menunjukkan kongurasi yang kelaik-ledakannya meningkat secara signikan, dengan penurunan yang drastis dalam perpindahan permanen dan peningkatan SEA dibandingkan dengan model dasar. Selain itu, struktur DAH memberikan kinerja lebih baik dibanding geometri auxetic lainnya. Kongurasi AHSP DAH optimal terdiri 15 sel pada arah horizontal dan 5 sel dalam arah vertikal, dengan sudut 0.1?, dan ketebalan 1.72 mm. Kongurasi ini mengungguli desain panel sandwich berinti busa aluminium optimal pada pengurangan perpindahan permanen dan peningkatan penyerapan energi spesik, dengan peningkatan sebesar 36.7% dan 155.13%, berturut-turut. Analisis sensitivitas global menggunakan SHapley Additive exPlanations (SHAP) mengungkapkan bahwa ketebalan sel adalah faktor paling kritikal yang mempengaruhi performa kelaik-ledakan, diikuti oleh jumlah sel dalam arah horizontal dan vertikal, serta sudut atau radius nodal untuk model CH. Selain itu, studi ini mengamati bahwa perilaku negative Poisson's ratio (NPR) global dari AHSP di bawah beban ledakan udara tidak konsisten karena kecepatan sangat tinggi dari impuls ledakan, terjadi terutama dalam kondisi khusus seperti kerapatan relatif kecil. Hasil menunjukkan bahwa perilaku NPR yang lebih
DESIGN OPTIMIZATION OF A NOVEL AUXETIC STRUCTURE BASED ON OCTAGONAL ANTI-CHIRAL GEOMETRY FOR BATTERY PROTECTION
The increasing population of electric vehicles is also accompanied by a rise in the accident rate caused by components in electric vehicles, one of which is battery damage. To minimize battery damage, a crashworthy protection system is needed. This is achieved by using materials that can absorb a large amount of energy. One such material with these properties is auxetic material, which is a structure with a negative Poisson's ratio, lightweight, and capable of absorbing large amounts of energy. This study is conducted by combining various types of auxetic materials or its base structure which then be optimized to obtain maximum Specific Energy Absorption (SEA). This study is carried out by conducting simulation using LS-Dyna. In this study, there are five new designs evaluated to analyze which design have an auxetic behavior. There are the combinations of chiral and hierarchical honeycomb, anti-chiral and half of hierarchical honeycomb, anti-chiral and half of hierarchical honeycomb with direction changes, anti-chiral and half of hierarchical honeycomb with ligament shape changes, and the combination of octagon base structure with anti-tri-chiral unit cell that connected with quadratic and hexagon base structure as addition. The design with octagonal base structure combined with anti-tri-chiral unit cell that connected with quadratic and hexagon base structure giving auxetic behavior, where the deformation kinematics in the form of rotating nodes appear and the lateral deformation of the structure is inward and resulting in a negative Poisson's ratio. Therefore, the novel auxetic design has been discovered and optimized with DFSS. In this study, DFSS together with Taguchi’s method and ANOVA will be employed to optimize structural design by leveraging simulation data. The most contributing factor in the simulation is the octagon ligament length and material with contribution percentage are 37.93% and 37.63%, respectively. The optimum configuration obtained from the study is the configuration with nodes diameter of 6.25 mm, octagon ligament length of 10 mm, quadratic vertical ligament length of 12 mm, and Al-Si12 material with thickness of 3 mm. This optimized design’s S/N ratio gain is 13.75 dB and yields 382.63% higher SEA compared to the baseline model, also it can protect the battery from failure by avoiding excessive deformation and have been proven by conducting the battery protection system simulation that the battery deformation is less than 2.9 mm which is under the deformation limit of battery before failure.
OPTIMIZATION OF DOUBLE-WALLED SANDWICH CRASH BOX COLUMNS WITH AUXETIC CORE USING DESIGN FOR SIX SIGMA METHOD
<p align="justify">With the increasing emphasis on vehicle safety, there is a critical need to enhance the crashworthiness of automotive components. One such component is the crash box, which has a vital part in absorbing energy during collisions and protecting vehicle occupants. Improving the crash box design is essential for effectively absorbing impact energy during collisions, thereby reducing the forces transmitted to vehicle occupants and improving overall safety. This research addresses this need by optimizing the crashworthiness of double-walled sandwich crash box columns through the incorporation of an auxetic core with a re-entrant geometry and the application of the Design for Six Sigma (DFSS) methodology, specifically Taguchi’s method. Employing numerical simulations with LS-DYNA, the study explores the crashworthiness response of thin-walled columns with auxetic cores, focusing on their unique energy absorption properties. The DFSS utilizes an L18 Taguchi orthogonal array using the Signal-to-Noise (S/N) ratio with the criteria of larger-the-better. For the optimization, the factors used include adhesive bonding, core and wall material, re-entrant width and angle, and the thicknesses of the inner wall, outer wall, and core are selected as optimization parameters. The optimized crash box design features tied contact adhesive bonding, core, and wall materials of AL 6061-T6 and Ti-6Al-4V respectively, an auxetic width of 7 mm, an auxetic angle of 60 degrees, inner and outer wall thicknesses of 2 mm, and a core thickness of 1.5 mm. The main aspect analyzed is the Specific Energy Absorption (SEA) of the crash box, chosen for its effectiveness in quantifying energy absorption efficiency relative to the weight of the crash box. Therefore, the results shows that the optimized crash box with an auxetic structure and double walls shows significant improvement over the baseline design, with a yield gain of 35.84 and 11.53 for SEA and S/N ratio, respectively. These findings underscore the potential of advanced materials and structured design methodologies in enhancing vehicle safety and pave the way for future innovations in crashworthy structures.<p align="justify">