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Mekanika: Majalah Ilmiah Mekanika
Published by Universitas Sebelas Maret
ISSN : 14127962     EISSN : 25793144     DOI : https://doi.org/10.20961/mekanika
Core Subject :
"Mekanika: Majalah Ilmiah Mekanika" is an open-access journal published by Mechanical Engineering Study Program, Faculty of Engineering, Universitas Sebelas Maret. Mekanika invites scholars, researchers and practioners who have interest in mechanical engineering to publish their articles and also provides forums for them to share their works and knowledge. Mekanika focuses on the area of materials engineering and science, design, energy, manufacturing and construction but is not limited to. Both English and Bahasa are accepted in this journal. Mekanika has two issues every year (March and September) and aims to publish more frequently in the future.
Arjuna Subject : Teknik (semua kategori) - Teknik Mesin
Articles 75 Documents
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Mechanical Properties of Unsaturated Polyester Composites Reinforced with Eggshell-Derived CaCO₃ Bio-filler as a Sustainable Material Kristiawan, Ruben Bayu; Priyanto, Kaleb; Shohih, Esa Nur
Mekanika: Majalah Ilmiah Mekanika Vol 24, No 2 (2025): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v24i2.104039

Abstract

The increasing demand for sustainable engineering materials has encouraged the development of polymer composites reinforced with bio-based fillers. Eggshell waste, which contains more than 90% biogenic calcium carbonate, represents an abundant and low-cost resource with potential as a reinforcing agent in thermoset composites. In this study, unsaturated polyester resin Bayesian Quantitative Trait Nucleotide (BQTN) 157 was reinforced with eggshell-derived calcium carbonate particles sized 105-149 µm, incorporated at volume fractions of 1-5%. Test specimens were produced using standardized moulds and evaluated for tensile properties in accordance with American Society for Testing and Materials (ASTM) D638 and for impact resistance using the Izod in ASTM D4812. The tensile results indicated a reduction in Ultimate Tensile Strength (UTS) of 6.7%, from 20.85 MPa for neat resin to 19.46 MPa at 5% filler, while the elastic modulus increased by 9.7%, from 1.44 GPa to 1.58 GPa. The impact resistance improved with filler addition, reaching a maximum of 91.75 J/m at a 3% filler concentration, representing a 15.7% increase, before slightly declining at higher concentrations. These findings demonstrate that eggshell-derived calcium carbonate is a promising sustainable bio-filler, with 3% volume identified as the optimum composition for practical composite applications.
Finite Element-Based Evaluation of Double-Hull Midsection Performance under Oblique Collision Malsyage, Dina; Bahatmaka, Aldias; Kirana, Arnova Chandra Cahya; Won, Lee Sang; Hee, Song Yeon
Mekanika: Majalah Ilmiah Mekanika Vol 24, No 2 (2025): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v24i2.106778

Abstract

Ship collisions pose a significant concern in maritime safety, particularly for double hull vessels operating in confined or high-risk areas. Understanding the structural response to collision is essential for improving crashworthiness. This study investigates the safety limits of a double-hull midsection ship under oblique impacts. Finite Element Analysis (FEA) was used to simulate three collision angles (45°, 60°, 90°) and four velocities (1, 3, 5, and 7 m/s). A benchmark study confirmed simulation accuracy with an error of less than 2%. The study reveals that impact angle and velocity significantly affect the ship's structural response. Perpendicular impacts (90°) with varying velocities produce the highest internal energy, reaching up to 28.99 MJ. In oblique impacts at 45°, the highest crushing force was generated, which reached 51.05 MN. Safety factor analysis indicates that impacts exceeding 3 m/s, especially those approaching perpendicular, lead to a decrease in structural integrity, falling below the acceptable limit. At 7 m/s and 90°, the stress on the inner hull exceeds the material's ultimate strength, indicating a potential for failure. To ensure structural safety, operational speeds should be limited to below 3 m/s. Findings highlight the importance of managing collision risks and guiding future ship design optimization.
Design of a Solar Power Plant System for Government Buildings in the Ibu Kota Nusantara of Indonesia Using HOMER Optimization Mohd Rosli, Mohd Afzanizam; Mahadi, Abram Anggit; Harsito, Catur; Prasetyo, Singgih Dwi
Mekanika: Majalah Ilmiah Mekanika Vol 24, No 1 (2025): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v24i1.92798

Abstract

Indonesia's social and political landscape necessitates a balanced distribution of development and a restructuring of its population and industries. In response, the government has relocated the capital from Jakarta to Ibu Kota Nusantara (IKN) in East Kalimantan, aiming to alleviate the pressures on the central city. Given the region's abundant solar energy resources, this paper explores the potential for investing in solar energy systems within government buildings to align with the innovative city initiative. The study employs the Hybrid Optimization Model for Electric Renewables (HOMER) to evaluate the feasibility of the government's solar energy plan. This simulation tool analyzes investment costs, energy generation potential, and economic viability. The HOMER configuration includes solar panels, batteries, and an inverter integrated with the on-grid electrical system, tailored to meet government building requirements. Simulation results indicate that the proposed model can generate approximately 828,980 kWh annually, with a total energy consumption of around 643,257 kWh. The estimated investment cost is IDR 20,581,290,000, with a production cost of IDR 1,407.11 per kWh and a net payback period of about seven years. This analysis suggests that solar energy systems are well-positioned to thrive in IKN's emerging business environment.
Development of a Worm–Spur Gear-Based Smart Motorised Valve for Intelligent Agricultural Irrigation Systems Nugraha, Muhamad Hanhan; Rusdja, Andy Permana; Risfi Silitonga, Muhammad Prasha; Rabbika, Anes Inda; Bustomi, Ahmad; CA, Zezero Meo; Y, Risat Dwi
Mekanika: Majalah Ilmiah Mekanika Vol 25, No 1 (2026): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v25i1.109595

Abstract

Agricultural irrigation systems require precise, effective, and efficient automatic valves; however, in practice, most of the technology used remains relatively simple, often leading to torque problems, leaks, and control limitations. This research aims to design an SDGMOV based on a worm-spur gear transmission and integrated with an IoT control system to support agricultural water regulation. The research methods include torque measurement using digital scales, CAD design and 3D printing with PLA, calculation of valve hydrostatic pressure, and force analysis using FEA. The control system was developed using an ESP32 microcontroller connected to a mobile application to enable remote monitoring and operation. The study’s results showed that the torque requirement of 1.62 N.m could be safely met by a servo motor that has a torque of 3.43 N.m. At the same time, FEA analysis of the bracket and cover revealed that the stress levels remained below the material’s permitted stress, with a FOS value exceeding 1.5. Additionally, the hydrostatic pressure calculation was significantly lower than the material’s strength, ensuring its safety for use. The implementation of the ESP32-based control system ensures stable, precise remote operation, enabling the SDGMOV design to enhance the precision, efficiency, and reliability of water distribution. 
Magnesium Addition and Treatment of Reinforcement Particles in Al6061 – Sea Sand Composite on Coefficients Friction and Wear Rate Akbar, Hammar Ilham; Atmaja, Muhammad Ilham Arbi; Surojo, Eko; Kusharjananta, Bambang; Fanani, Reza Aldiansyah
Mekanika: Majalah Ilmiah Mekanika Vol 23, No 1 (2024): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v23i1.78335

Abstract

Aluminium matrix composite is a composite material that can be used as reinforcement to increase the tribological properties of composite. The process of manufacturing the Al6061-Sea sand composite used the stir casting method with stirring time of 10 minutes and speed of 600 rpm. Stir casting specimens were manufactured with height dimension of 20 mm and diameter of 10 mm. After that, the specimen was friction tested using the pin on disc method. The highest coefficient of friction was the specimen without electroless coating with the addition of 2 wt% Mg of 0.634. The more mass fraction of sea sand, the higher the porosity, and the lower the density. An electroless coating process can be carried out on reinforcing particles. This study aims to determine the effect of addition of Mg and treatment of reinforcing particles on the Al6061-Sea sand composite on the coefficient of friction and wear rate. The coefficient of friction, the specimen density increased, the porosity and the wear rate, decreased. This occurred because the reinforcement particle size of sea sand bonded strongly to aluminium matrix. The highest coefficient of friction was the electroless coating with the addition of 2 wt% Mg of sea sand, which was 0.646.
Optimizing Energy Efficiency in Vertical Axis Wind Turbines: A CFD Analysis of Inlet Velocity and Fluid Type Impact Nubli, Haris; Baek, Seung Jun; Nur Afiqoh, Nabella Sofa; Trisnoaji, Yuki; Prasetyo, Singgih Dwi
Mekanika: Majalah Ilmiah Mekanika Vol 24, No 2 (2025): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v24i2.104188

Abstract

The development of Vertical Axis Wind Turbines (VAWTs) has become a key focus in renewable energy utilization due to their ability to operate at low wind speeds and their simple design. This study aims to analyze the effects of inlet velocity variations and fluid physical properties on flow patterns, turbulence, and kinetic energy in VAWTs. The simulation was conducted using the Computational Fluid Dynamics (CFD) method, based on ANSYS Fluent, for a 2D turbine model with a diameter of 12 cm. Inlet velocity variations of 10, 11, 12, 13, and 14 m/s were tested using three types of fluids: air, helium, and hydrogen. The results show that increasing inlet velocity transforms the flow pattern from stable to complex, with greater turbulence forming behind the cylinder. Air exhibited the highest kinetic energy at low to medium velocities, ranging from 10 to 12 m/s, which was up to 24.7% higher than that of helium and 3.8% higher than that of hydrogen. At higher velocities, 13–14 m/s, the kinetic energy difference among the three fluids decreased to less than 1.5%. Furthermore, outlet velocity was consistently higher than inlet velocity for all fluids, with hydrogen achieving the highest acceleration at 14 m/s.
Performance of Vortex Turbines with Two-Stage Radial-Offset Runners Fathurrohman, Aulia; Septiyanto, Muhamad Dwi; Andriyanto, Solikin; Prasetyo, Ari; Tjahjana, Dominicus Danardono Dwi Prija; Hadi, Syamsul
Mekanika: Majalah Ilmiah Mekanika Vol 24, No 2 (2025): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v24i2.105045

Abstract

Gravitational water vortex turbines are environmentally friendly power generation systems that convert the energy of vortex water flow into mechanical energy using turbine runners. This study aims to analyze the effect of a two-stage configuration with varied radial runner positions and water discharge on turbine performance. Experiments were conducted using a low-speed water channel with a conical basin to generate vortex flow. Savonius-type runners were installed vertically in two stages with radial positions of 0.5, 0.6, and 0.7 relative to the basin radius. Each configuration was tested at several water discharge rates. The primary parameter measured was mechanical power output, which was obtained using torque sensors and rotational speed meters to provide precise data. Results showed that the radial position 0.5 produced the best performance, generating 12.28 watts in the first and 16.68 watts in the second. Runner position and water discharge directly influenced vortex stability and energy conversion efficiency. The two-stage configuration with optimal runner placement significantly improved system efficiency. These findings suggest that the two-stage vortex turbine design is promising for small-scale power generation in remote areas.
The Effect of Battery Manufacturing Under Different Conditions and Its Contribution to CO Emissions Putra, Mufti Reza Aulia; Nizam, Muhammad; Setiawan, Bagas; Santoso, Henry Probo
Mekanika: Majalah Ilmiah Mekanika Vol 24, No 1 (2025): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v24i1.99093

Abstract

Lithium-ion (Li-ion) batteries play a crucial role as energy sources for electric vehicles and portable electronic devices due to their high energy density. However, this high energy density leads to increased temperatures during operation, which negatively impacts the performance of nickel strips as the primary electrical connectors within the battery. Suboptimal welding of nickel strips results in safety issues, evidenced by gas leaks from the battery. This research aims to explore the impact of welding defects on battery performance, considering the role of gas sensors in enhancing safety. The test samples used are nickel strips with a thickness of 0.1 mm and a width of 5 mm, evaluated using varying currents of 10A, 20A, 40A, and 50A at room temperature. Observations were made regarding nickel degradation, followed by an analysis of carbon monoxide (CO) and carbon dioxide (CO₂) emissions. The results indicate a temperature increase of up to 78,8°C at the nickel tip, along with the identification of three welding points representing efficient values. Furthermore, the welding results on the battery produced microstructural defects that led to an increase in CO emissions by 18 ppm and CO₂ emissions by 500 ppm during the 1C charging process until reaching 100%.
Optimization of Photovoltaic Performance Through the Integration of a Heatsink–Blower Cooling System Under Solar Simulator Testing Conditions Prasetyo, Singgih Dwi; Farid, Muh. Farhan Atha; Fernandio Prasetyo, Tyo Febrino; Nur Afiqoh, Nabella Sofa; Novena, Nindia Nova; Trisnoaji, Yuki; Lumban Gaol, Mangisi Larixon; Sinaga, Febrianto; Kombe, Godlisten Gladstone; Shame, Buruhan Haji
Mekanika: Majalah Ilmiah Mekanika Vol 25, No 1 (2026): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v25i1.114555

Abstract

This study examines the impact of a heatsink-based cooling system, combined with forced airflow, on the thermal and electrical performance of a photovoltaic (PV) module under controlled irradiance conditions provided by a solar simulator. The cooling configuration employed is energy-efficient and straightforward, utilizing active convection enhanced by a blower in selected trials. Two primary conditions were compared: PV without cooling and PV with different cooling configurations. The experimental results indicate that the PV + Heatsink + Blower configuration achieved the highest average electrical efficiency of 13.43%, whereas the PV Only configuration recorded the lowest, 12.45%. This difference demonstrates that temperature regulation through a combination of heatsink and assisted airflow significantly improves electrical energy conversion. Furthermore, maintaining a lower, more stable operating temperature contributes to consistent power output and reduces heat accumulation, which can accelerate performance degradation. Overall, the findings suggest that integrating a low-energy, straightforward cooling design can be an effective strategy to enhance PV performance, particularly in testing environments that use a solar simulator.
Enhancing Lubrication System Efficiency in Marine Diesel Engines with Centrifugal Separators - a Case Study Of LPG/C Arimbi: Technical and Cost-Effective Perspectives Tuswan, Tuswan; Rasyad, Muhammad Fuad; Budiarto, Untung; Mursid, Ocid; Tanzani, Andra; Yulianti, Serliana; Ismail, Abdi; Ariesta, Rizky Chandra
Mekanika: Majalah Ilmiah Mekanika Vol 23, No 1 (2024): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v23i1.83063

Abstract

The lubrication system in an engine is critical for reducing friction between components, preventing wear, reducing heat, protecting components from deposits, and sealing. Maintaining and extending the life of lubricants is crucial for lowering lubricant usage costs. A centrifugal separator is an auxiliary machine that cleans and separates two insoluble liquids with different densities. This study aims to evaluate the efficiency of lubricant life, lubricant usage cost savings, and return on investment time for a centrifugal separator. The study uses a case study of LPG/C Arimbi, where a centrifugal separator has helped maintain lubricants, prevent wear, and separate fuel and free water from lubricants. The centrifugal separator can also maintain Total Base Number (TBN) and viscosity values by filtering solid particles or wear elements up to a size of 0.5 µm. The study found that the difference in lubricant life was 11,780 hours, and the cost savings obtained were IDR 186,456,666 per year. The return on investment time for purchasing a centrifugal separator is three years and two months, assuming an average working hours of LPG/C Arimbi every year of 3,660 hours. Therefore, using a centrifugal separator can improve the efficiency of lubricant life and reduce lubricant usage costs, providing a positive return on investment in the long run.

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