Jurnal Vokasi Mekanika (VoMek)

Experimental Study Of Wear Testing Of ASTM 440C Steel On A Ball-On-Disc Tribometer Using Variations Of Lubricants

2025-12-01T00:28:41+00:00

Bearings are important components in industry that function to reduce friction between moving parts for smoother and more efficient movement. However, friction that occurs can cause wear on the bearing surface. This study aims to analyze the wear volume, wear width, and wear rate of ASTM 440C steel material with variations of SAE 10W-30, SAE 10W-40, and SAE 140 lubricants at rotational speeds of 180 rpm, 270 rpm, and 310 rpm. Testing was carried out using a tribometer. ball-on-disc with a constant time of 10 minutes. The test results showed that the lowest wear width was obtained in SAE 10W-40 lubricant of 259.806 µm at 180 rpm, while the highest value of 417.894 µm also occurred in SAE 10W-40 at 270 rpm. The lowest wear volume was recorded in SAE 10W-40 of 0.0225 mm³ at 180 rpm, while the highest was 0.0942 mm³ at 270 rpm with the same lubricant. For the wear rate, the lowest value of 0.50 × 10⁻⁸ g/mm²·s was found in SAE 140 lubricant at 180 rpm, while the highest was 1.58 × 10⁻⁸ g/mm²·s occurred in SAE 10W-40 at 270 rpm. Overall, SAE 10W-40 lubricants are more suitable for use at low revs, while SAE 140 lubricants are recommended for high revs due to their greater viscosity and resistance to wear.

Strength and Deformation Analysis of the Tubular Space Frame of the Megathrust Electric Car with Variations in Dimensions and Materials Using the Finite Element Analysis (FEA) Method

2025-12-01T00:28:50+00:00

The development of electric vehicles in Indonesia has grown rapidly, supported by the Indonesian Electric Car Competition (KMLI) which encourages innovation in designing lightweight yet strong vehicle frames. The tubular space frame of the “Megathrust Electric” car previously used ASTM A36 steel with a total weight of 32 kg, which was considered inefficient as it increased power consumption and reduced overall performance. This study aims to analyze the effect of pipe dimension variations and alternative materials, namely Aluminium alloy 6061 and 6063, on the strength and deformation of the frame. The method employed is Finite Element Analysis (FEA) using SolidWorks software under static loading conditions that represent real operating scenarios. The pipe variations examined include 19.05 mm diameter with 2.5 mm thickness and 25.4 mm diameter with 2 mm thickness. The simulation results show that the 25.4 × 2 mm Aluminium alloy 6061 configuration provides the best structural performance with a maximum stress of 55.07 MPa, deformation of 1.583 mm, and a safety factor (FOS) of 5.012. In contrast, the 19.05 × 2.5 mm Aluminium alloy 6063 configuration is lighter but exhibits higher stress (184.4 MPa) and a lower safety factor (1.161). Therefore, the Aluminium Alloy 6061 pipe with 25.4 mm diameter is recommended as the optimal frame design, offering a balance between strength, stiffness, and weight efficiency to support the performance of electric vehicles in competition.

Analysis of Magnus Turbine Addition on a 1700 DWT Tanker Using Computational Fluid Dynamics Simulation

2025-12-01T00:29:02+00:00

Turbin magnus merupakan turbin yang berfungsi sebagai sistem propulsi tambahan pada kapal dengan tujuan meningkatkan efisiensi energi dan mengurangi emisi gas buang. Tujuan penelitian ini adalah untuk menganalisis perbandingan performa turbin magnus tipe flettner rotor dan thom rotor terhadap koefisien lift (Cℓ), koefisien drag (Cd), gaya thrust (Fr), serta hambatan total baru kapal (RT New). Metode penelitian menggunakan simulasi berbasis Computational Fluid Dynamics (CFD) dengan menggunakan software Ansys Fluent 2025 R1 Student Version. Hasil penelitian menunjukkan bahwa turbin magnus tipe thom rotor memiliki nilai Cℓ lebih tinggi sebesar 0,3364; 0,3276; 0,3157 pada kecepatan 5 m/s, 10 m/s, dan 15 m/s dibandingkan flettner rotor sebesar 0,2785; 0,2508; 0,2442 pada kecepatan 5 m/s, 10 m/s, dan 15 m/s dengan penurunan nilai lebih stabil pada variasi kecepatan angin. Sedangkan nilai Cd thom rotor sebesar 0,6487; 0,5333; 0,4959 pada kecepatan 5 m/s, 10 m/s, dan 15 m/s juga lebih besar dibandingkan flettner rotor sebesar 0,5705; 0,4537; 0,4229 pada kecepatan 5 m/s, 10 m/s, dan 15 m/s. Perhitungan gaya thrust (Fr) menunjukkan peningkatan signifikan pada kedua tipe rotor seiring kenaikan kecepatan aliran, dengan kontribusi terbesar pada thom rotor. Hambatan total baru kapal (RT New) menurun secara relatif terhadap kondisi awal, menandakan adanya efisiensi propulsi tambahan. Maka penambahan turbin magnus mampu memberikan gaya dorong tambahan, mengurangi hambatan total, serta meningkatkan efisiensi operasional kapal. Thom rotor menghasilkan gaya angkat yang lebih stabil, sementara flettner rotor lebih efisien dalam menekan hambatan, sehingga pemilihan tipe rotor dapat disesuaikan dengan kebutuhan operasional kapal.

Characterization of Density and Stability of Oil Palm Empty Fruit Bunch Briquettes without Binder under Variations of Molding Temperature and Compaction Pressure

2025-12-01T00:29:12+00:00

The dependence on fossil fuels in Indonesia continues to increase in line with the growing energy consumption, thus necessitating alternative energy sources that are more environmentally friendly and sustainable. Oil palm empty fruit bunches (OPEFB) are agro-industrial waste with great potential to be utilized as raw material for briquette production; however, their utilization remains suboptimal. This study aims to analyze the effect of molding temperature and compaction pressure on the density and stability of binderless OPEFB briquettes. The research method employed is experimental, using a quantitative descriptive-analytical approach with non-carbonized briquettes. The treatment variations include molding temperatures (230°C, 250°C, and 280°C) and compaction pressures (1 MPa, 3 MPa, and 5 MPa) applied to two types of materials, namely dried and undried OPEFB. The results indicate that increasing temperature and compaction pressure significantly enhances briquette density. At a temperature range of 250–280°C and a pressure of 5 MPa, the briquettes achieved the highest density (>1.0 g/cm³) with strong shape stability. The thermoplastic lignin content in OPEFB melts at high temperatures, acting as a natural binder. Briquettes with a density ≥0.80 g/cm³ exhibited strong physical integrity, while those with a density <0.70 g/cm³ tended to be brittle. It can be concluded that the optimum conditions for producing high-quality binderless OPEFB briquettes are achieved at a temperature range of 250–280°C and a compaction pressure of 5 MPa, resulting in briquettes with excellent density and shape stability suitable as a renewable alternative energy source

LMTD-Based and Effectiveness Analysis of Cooling Performance on a 5 kW Axial Flux Permanent Magnet BLDC Motor Design Using CFD Simulation

2025-12-01T00:29:23+00:00

Axial flux type BLDC motors primary issue is the high operating temperature of the stator and winding components, which can lower system efficiency and hasten the deterioration of the quality of the insulation material. This study is to examine the effects of geometric alterations to the cooling system, such as axial fins on the housing side and curved fins on the casing, on the temperature distribution of a 5-kW axial flux permanent magnet BLDC motor. Convection and conduction heat transport in the cooling system were modeled using ANSYS Fluent software and computational fluid dynamics (CFD) simulation techniques. The Log Mean Temperature Difference (LMTD) and the cooling design's relative efficacy in comparison to the baseline state are the primary metrics that are examined. According to the simulation results, the maximum winding temperature may be lowered to 311 K and the cooling distribution in the rotor, casing, and housing can be improved by adopting curved fin casing and axial fin housing. As the temperature differential between the coolant and the motor surface narrows, the LMTD value drops from the initial condition (5.10 K to 13.94 K), suggesting a more effective heat transfer process. Furthermore, the cooling system's efficiency has more than doubled since its original design. Overall, the study's findings demonstrate that enhancing the cooler's geometric design can increase the BLDC motor's thermal performance and prolong component life.

The Contribution of Listening Skills and Learning Motivation to Arabic Learning Outcomes at Muhammadiyah Vocational School, Batam City

2025-12-01T00:29:33+00:00

Arabic language learning at Muhammadiyah Vocational School in Batam City faces several challenges: the perception of Arabic as a difficult subject, students’ anxiety in learning Arabic, ineffective classroom management, unstructured listening practice, and varying levels of learning motivation. Therefore, this study aims to analyze the contribution of listening skills and learning motivation, both partially and simultaneously, to the Arabic learning outcomes of students at Muhammadiyah Vocational School in Batam City. Using a quantitative descriptive-correlational design with a sample of 132 tenth-grade students, learning outcomes data were obtained through tests, while listening skills and learning motivation were measured using questionnaires; analysis was conducted through correlation and multiple regression (SPSS). The results show that listening skills contributed positively to learning outcomes with a determination coefficient of 11.9% (effective contribution = 9.12%; relative contribution = 37.23%), learning motivation contributed 41.9% (effective contribution = 38.71%; relative contribution = 62.74%), and simultaneously both contributed 44.8% to Arabic learning outcomes. Practically, strengthening structured listening practices (authentic oral input, periodic assessments) and motivational interventions (goal setting, formative feedback, varied methods) are recommended to improve performance; socially, enhancing listening literacy and motivation is expected to foster a more focused, diligent, and collaborative academic culture within the vocational school environment. This study provides added value by integrating the analysis of the foundational role of listening skills and the psychological factor of motivation in Arabic learning within the vocational context, and by presenting estimates of both partial and simultaneous contributions as a basis for designing policies and teaching strategies

Characterization Of Bioethanol From Cassava As A Fuel In Gasoline Engines

2025-12-01T00:29:38+00:00

The energy demand in Indonesia continues to increase, particularly in the transportation sector, which remains highly dependent on fossil fuels such as gasoline. This dependency causes several issues, including the depletion of fossil fuel reserves and the rise of greenhouse gas emissions that negatively impact the environment. One potential solution to address these challenges is the development of bioethanol as a renewable and environmentally friendly alternative fuel. Bioethanol can be produced from starchy materials, one of which is white cassava (Manihot esculenta), known for its high productivity and wide availability in Indonesia. The production process of bioethanol consists of several stages, including liquefaction, fermentation, and distillation, where fermentation temperature plays a crucial role in determining the ethanol yield. Previous studies have shown that variations in fermentation temperature significantly influence the efficiency of bioethanol production. This study aims to characterize bioethanol produced from cassava fermentation at various temperature variations and to evaluate its potential as a fuel for gasoline engines. The results are expected to contribute to the improvement of bioethanol production efficiency and to promote cassava utilization as a renewable energy source in supporting national energy sustainability.