23 research outputs found

    Sifat Mekanik Packaging Kertas Berbahan Dasar Selulosa Alga Cladophora

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    Alga cladophora merupakan salah satu alga yang banyak tumbuh di pesisir pantai Indonesia. Alga cladophora memiliki kandungan selulosa yang cukup tinggi sehingga sangat berpotensi untuk dimanfaatkan sebagai bahan baku material packaging kertas. Tujuan dari penelitian ini adalah mempelajari sifat mekanik kertas yang berbahan dasar selulosa alga cladophora. Pada penelitian ini, selulosa alga cladophora diekstraksi melalui beberapa tahapan proses yang meliputi proses alkalisasi dan proses hidrolisis. Proses alkalisasi dilakukan dengan merefluks alga cladophora didalam larutan NaOH (1%, 5%, 10%, 15% dan 17.5%) pada temperatur 100 ℃ selama 2 jam. Proses hidrolisis dilakukan dengan merefluks alga cladophora hasil alkalisasi didalam larutan asam sulfat 1 M pada temperatur 100 ℃ selama 2 jam. Proses pembuatan kertas dilakukan dengan metode solution casting. Kandungan selulosa diukur dengan menggunakan metode Chesson-Datta. Sifat mekanik dari kertas selulosa alga cladophora diukur dengan pengujian tarik. Dari hasil pengukuran kandungan selulosa dapat disimpulkan bahwa selulosa yang diekstrasi dengan menggunakan larutan NaOH 17.5% memiliki tingkat kemurnian yang paling tinggi, yakni 94. 76%. Selulosa yang diekstraksi dengan menggunakan larutan NaOH 17.5% menghasilkan kertas dengan permukaan yang paling halus serta memiliki kekuatan tarik dan kekakuan yang paling tinggi dibandingkan dengan kertas lainnya yang dihasilkan dalam penelitian ini, yakni 57.68 MPa dan 10.12 GPa

    Numerical Study of Experiment Setup for Aluminum Foam Sandwich Construction Subjected to Blast Load

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    In the designing an armored fighting vehicle (AFV), blastworthy construction to protect military personnel from landmines explosion is urgently needed. This is due to a large number of fatalities of army personnel in the state conflict zones. To achieve this blastworthy construction, the design of AFV floor structures needs to be able to sustain structural intrusion with lower dynamic acceleration against blast load. The blastworthy structures can be achieved through absorbing the blast impact load by using an aluminum foam sandwich (AFS) construction. During the design iteration process, a good correlation between numerical simulation and blast impact experiment is required. In this study, an experimental setup to assess the AFS construction for blast load performance evaluation was introduced. This study is started with an evaluation of jigs and fixtures structural strength, load cell structure requirement, and data acquisition to record maximum displacement, maximum acceleration, and reaction force in the load cells. From the evaluation, it was found that the jig and fixture structural configuration requires high load retention at the bolt joint location to avoid high stress concentration. For the load cell structure, it is recommended to place the load cell position in the pure axial stress direction so that there is no plastic deformation interference with the instrumentation. The data acquisitions will record the acceleration and reaction force of the AFS construction. The simulation results are also used to design the load cell and to select the accelerometer capability range. This study is expected to provide a robust experimental data during blast impact load testing of blastworthy AFS floor structure.

    The Influence of Forming Effects on The Bending Crush Behavior of Top-Hat Thin–Walled Beams

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    This paper presents a study on the effects of forming process of a top–hat thin–walled beams to its bending crush resistance under dynamic bending load. The thin–walled beam was formed using a one step deep drawing. HyperForm software simulated the forming process and mapped its effects such as thickness variations and residual plastic strains in to the crash analysis models. Then the dynamic bending crush analysis was carried out using LS–DYNA by using the geometry and materials data obtained from the forming analysis results. For each material model, the analyses were carried out for model with and without the forming effects. The bending crush behavior of the top–hat thin–walled beams were then analyzed to compare between the simulations with and without forming effects. The results show that by incorporating the effect of forming process, the bending crush resistance of the thin–walled beams is increase by 4.7%. The introduction of strain rates to the material model increases even further on the bending crush resistance of the thin–walled beam

    Analisis Struktur Octet-Truss Lattice Sebagai Struktur Penyerap Energi Pada Subfloor Helikopter

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    Semakin meningkatnya penggunaan helikopter dalam transportasi udara menyebabkan semakin meningkatnya peluang terjadinya kecelakaan. Sebagian besar kecelakaan pada helikopter adalah jatuh dan merusak bagian bawah struktur badan helikopter (subfloor) akibat beban dinamik. Untuk meningkatkan keamanan dan mengurangi resiko terjadinya cedera fatal pada penumpang perlu dilakukan kajian crashworthiness pada helikopter.Salah satu cara manajemen energi serap pada struktur helikopter terhadap tabrakan adalah dengan mengoptimalkan struktur penyerap energi. Peningkatan energi serap dapat dilakukan dengan menggunakan geometri lattice sebagai struktur penyerap energi. Struktur lattice merupakan solusi yang menjanjikan untuk dipergunakan sebagai struktur penyerap energi impak. Tugas akhir ini difokuskan untuk melakukan studi mengenai karakteristik respon octet-truss lattice ketika dikenakan beban impak dan pengaplikasiannya pada struktur subfloor helikopter dengan metode elemen hingga. Analisis  numerik untuk studi perbandingan konfigurasi struktur cruciform, struktur octet-truss lattice bertumpuk uniform dengan octet-truss lattice bertumpuk double taper sebagai struktur penyerap energi. Dengan adanya teknologi manufaktur aditif, struktur lattice dapat dengan mudah diproduksi menggunakan teknik selective laser sintering (SLS). Material yang digunakan dalam simulasi numerik berupa paduan alumunium AlSi-12 hasil manufaktur SLS. Hasil konfigurasi lattice akan digunakan pada subfloor helikopter dan  dibandingkan dengan struktur cruciform. Setelah dilakukan simulasi numerik dengan metode elemen hingga akan dilihat struktur mana yang mempunyai specific energy absorb tertinggi . Hasil ini menunjukkan bahwa struktur lattice dengan konfigurasi double taper memiliki specific energy absorb tetinggi sebesar 34.44 kJ/kg. Dari hasil pemodelan elemen hingga didapat konfigurasi octet-truss lattice dengan double taper memiliki potensi yang besar sebagai struktur penyerap energi dimasa depan

    Design Optimization of Auxetic Structure for Crashworthy Pouch Battery Protection Using Machine Learning Method

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    In 2021, the electric vehicles (EVs) market reached a record-breaking 6.5 million vehicles, and it will continuously grow to USD 31 million in 2030. However, the risk of battery damage should be reduced using a lightweight crashworthy protection system, which can be performed through design optimization to achieve maximum Specific Energy Absorption (SEA). Maximum SEA can be gained by selecting a material with a light weight and high energy absorption properties. An auxetic-shaped cell structure was used since its negative Poisson ratio yields better energy absorption. The research was performed by varying the auxetic cell shape (Re-entrant, Double Arrow, Star-shaped, Double-U), material selection (GFRP, CFRP, aluminum, carbon steel), and geometry variables until the maximum possible SEA was reached. The Finite Element Method (FEM) was used to simulate the impact and obtain the value of the SEA of the varied auxetic cellular structure design samples. The design variation amounted to 100 samples generated using Latin Hypercube Sampling (LHS) to distribute the variables. Finally, the Machine Learning method predicted the design that yielded maximum SEA. The optimization process through Machine Learning consisted of two processes: model approximation using an Artificial Neural Network (ANN) and variable optimization using a Nondominated Sorting Genetic Algorithm-II (NSGA-II). The optimization demonstrated that the maximum SEA resulted from Star-shaped auxetic cells and aluminum material with a thickness of 2.95 mm. This design yielded 1220% higher SEA compared to the baseline model. A numerical simulation was also carried out to validate the result. The prediction error amounted to 6.7%, meaning that the approximation model can successfully predict the most optimum design. After the complete battery system configuration simulation, the design could also prevent excessive battery deformation. Therefore, the optimized structure can protect the battery from failure

    Design Optimization of Auxetic Structure for Crashworthy Pouch Battery Protection Using Machine Learning Method

    No full text
    In 2021, the electric vehicles (EVs) market reached a record-breaking 6.5 million vehicles, and it will continuously grow to USD 31 million in 2030. However, the risk of battery damage should be reduced using a lightweight crashworthy protection system, which can be performed through design optimization to achieve maximum Specific Energy Absorption (SEA). Maximum SEA can be gained by selecting a material with a light weight and high energy absorption properties. An auxetic-shaped cell structure was used since its negative Poisson ratio yields better energy absorption. The research was performed by varying the auxetic cell shape (Re-entrant, Double Arrow, Star-shaped, Double-U), material selection (GFRP, CFRP, aluminum, carbon steel), and geometry variables until the maximum possible SEA was reached. The Finite Element Method (FEM) was used to simulate the impact and obtain the value of the SEA of the varied auxetic cellular structure design samples. The design variation amounted to 100 samples generated using Latin Hypercube Sampling (LHS) to distribute the variables. Finally, the Machine Learning method predicted the design that yielded maximum SEA. The optimization process through Machine Learning consisted of two processes: model approximation using an Artificial Neural Network (ANN) and variable optimization using a Nondominated Sorting Genetic Algorithm-II (NSGA-II). The optimization demonstrated that the maximum SEA resulted from Star-shaped auxetic cells and aluminum material with a thickness of 2.95 mm. This design yielded 1220% higher SEA compared to the baseline model. A numerical simulation was also carried out to validate the result. The prediction error amounted to 6.7%, meaning that the approximation model can successfully predict the most optimum design. After the complete battery system configuration simulation, the design could also prevent excessive battery deformation. Therefore, the optimized structure can protect the battery from failure

    Anatomy of Injury Severity and Fatality in Indonesian Traffic Accidents

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    There has been a steady increase in traffic accidents with major injuries in Indonesia over the last 10 years, especially those with a score higher than 3 on the Abbreviated Injury Scale (AIS). Frontal, side, and rear collisions, as well as pedestrian impact are modes of accident that contribute to the majority of injuries or fatalities. Based on age classification, the 16-30 age group are the most vulnerable road users in Indonesia. Traffic accidents in Indonesia are dominated by motorcycles, which also contribute the highest portion of fatalities and major injuries (AIS score > 3). Most traffic accidents can be attributed to human, road and environmental, or vehicle factors. Careless driving and unruly behavior of the driver are the main causes of accidents in Indonesia. Statistical data and analyses on traffic accidents in Indonesia can be used to develop a comprehensive strategy and policy to reduce the number of fatalities and severe injuries of road accidents in Indonesia. There is a need to balance the high growth of motor vehicles with adequate infrastructure. Good driver education as well as vehicle safety and crashworthiness regulations are required in order to reduce traffic accident fatalities

    Design and Numerical Analysis of Electric Vehicle Li-Ion Battery Protections Using Lattice Structure Undergoing Ground Impact

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    Improvement in electric vehicle technology requires the lithium-ion battery system’s safe operations, protecting battery fire damage potential from road debris impact. In this research a design of sandwich panel construction with a lattice structure core is evaluated as the battery protection system. Additive manufacturing technology advancements have paved the way for lattice structure development. The sandwich protective structure designs are evaluated computationally using a non-linear dynamic finite element analysis for various geometry and material parameters. The lattice structure’s optimum shape was obtained based on the highest Specific Energy Absorption (SEA) parameter developed using the ANOVA and Taguchi robust design method. It is found that the octet-cross lattice structure with 40% relative density provided the best performance in terms of absorbing impact energy. Furthermore, the sandwich panel construction with two layers of lattice structure core performed very well in protecting the lithium-ion NCA battery in the ground impact loading conditions, which the impactor velocity is 42 m/s, representing vehicle velocity in highway, and weigh 0.77 kg. The battery shortening met the safety threshold of less than 3 mm deformation

    Design and Numerical Analysis of Electric Vehicle Li-Ion Battery Protections Using Lattice Structure Undergoing Ground Impact

    No full text
    Improvement in electric vehicle technology requires the lithium-ion battery system’s safe operations, protecting battery fire damage potential from road debris impact. In this research a design of sandwich panel construction with a lattice structure core is evaluated as the battery protection system. Additive manufacturing technology advancements have paved the way for lattice structure development. The sandwich protective structure designs are evaluated computationally using a non-linear dynamic finite element analysis for various geometry and material parameters. The lattice structure’s optimum shape was obtained based on the highest Specific Energy Absorption (SEA) parameter developed using the ANOVA and Taguchi robust design method. It is found that the octet-cross lattice structure with 40% relative density provided the best performance in terms of absorbing impact energy. Furthermore, the sandwich panel construction with two layers of lattice structure core performed very well in protecting the lithium-ion NCA battery in the ground impact loading conditions, which the impactor velocity is 42 m/s, representing vehicle velocity in highway, and weigh 0.77 kg. The battery shortening met the safety threshold of less than 3 mm deformation

    Finite Element Analysis of Liquefied Ammonia Tank for Mobility Vehicles Employing Polymers and Composites

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    Hydrogen has attracted global attention as a clean secondary energy source and has numerous possible applications, including fuel for vehicles. To store the hydrogen effectively, ammonia is considered promising due to high hydrogen density, stability, and total energy efficiency. Adopting ammonia as a fuel in vehicles requires a proper fuel tank design to fulfill the required volumetric content and safety standards, without neglecting the economic objectives. In general, a type-IV pressure vessel is utilized as a fuel tank because it is the lightest one, compared to other types of pressure vessel. This paper focuses on the effort to develop a lightweight type-IV ammonia pressure vessel designed for mobility vehicles. The material combination (liner and composite) and composite stacking sequence are analyzed for both burst and impact tests by using a finite element method. Two polymer materials of polyethylene terephthalate (PET) and polypropylene (PP) are evaluated as the liner considering their ultimate tensile strength, density, cost, and compatibility with ammonia, while carbon-fiber-reinforced polymer (CFRP) and glass-fiber-reinforced polymer (GFRP) are adopted as composite skins. In addition, five composite stacking sequences are analyzed in this study. Von Mises stress and Hashin’s damage initiation criteria are used to evaluate the performance of liner and composite, respectively. As the results, PP-based pressure vessels generate lower stress in the liner compared to PET-based vessels. In addition, CFRP-based pressure vessels have a higher safety margin and are able to generate lower stress in the liner and lower damage initiation criteria in the composite skin. The material combination of PP-CFRP with a stacking sequence of [90/±30/90]3s gives the lowest maximum stress in the liner during the burst test, while, for the impact test, the stacking sequence of [90/±θ/90]3s is considered the most appropriate option to realize a lower stress at the liner, although this tendency is relatively small for vessels with PP liner
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