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All Journal Jurnal Rekayasa Mesin Mekanika: Majalah Ilmiah Mekanika Jurnal Inovasi Mesin
Nubli, Haris
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Mechanical Engineering

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Optimization Design of NACA 4412 Airfoil Based on Genetic Algorithm for Efficiency and Maximum Lift Force Laksono, Aryo Eko; Bahatmaka, Aldias; Fitriyana, Deni Fajar; Laksono, Galih Tri; Habibullah, Muhammad; Nubli, Haris; Hyung, Cho Joung
Jurnal Rekayasa Mesin Vol. 20 No. 2 (2025): Volume 20, Nomor 2, Agustus 2025
Publisher : Mechanical Engineering Department - Semarang State Polytechnic

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32497/jrm.v20i2.6531

Abstract

The NACA 4412 airfoil, renowned for its exceptional subsonic aerodynamic performance, faces critical operational constraints including elevated drag characteristics and premature stall onset at high angles of attack. While previous investigations have independently examined internal slot modifications and gurney flap implementations for aerodynamic enhancement, the synergistic potential of their combined application to the NACA 4412 configuration remains largely unexplored. This research presents a comprehensive optimization study that strategically integrates internal slot geometry with gurney flap configuration to maximize lift coefficient (CL) and aerodynamic efficiency (CL/CD) through advanced genetic algorithm optimization. The methodology employed high-fidelity computational fluid dynamics simulations using FLUENT with Spalart-Allmaras turbulence modeling, validated against experimental data to ensure accuracy. PCHIP numerical interpolation techniques were utilized to estimate aerodynamic coefficients across comprehensive angle-of-attack ranges not directly simulated. The optimized configuration demonstrated remarkable performance improvements, including a 75.68% increase in lift coefficient, an extension of the critical stall angle from 14° to 16°, enhanced aerodynamic efficiency, and significantly improved flow stability with reduced separation characteristics. These findings establish that the synergistic combination of internal slot and gurney flap modifications can fundamentally transform NACA 4412 aerodynamic performance, particularly excelling in high-angle-of-attack operational scenarios.
The Effect of Variations In Clear Coat Application Distance On The Glitter of The Painting Results Fatkhurokhman, Najib; Hidayat, Hanif; Nubli, Haris
Jurnal Inovasi Mesin Vol. 7 No. 2 (2025): OCTOBER 2025
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jim.v7i2.22624

Abstract

Painting defects in  the repainting  process in the vehicle body repair industry are still a common problem. The main factor causing painting defects is manual application that is not in accordance with standard operating procedures. Painting the vehicle body functions to protect the surface and increase aesthetic value, but there are still frequent painting defects such as rough surfaces, spots, and melting due to improper application. This study aims to examine the distance of application of clear coat to the quality of painting results with minimal defects. The research design used was an experimental  research design with a variety of spraying distances of 10 cm, 15 cm, 20 cm, 25 cm and the measurement of the gloss value was carried out using a gloss meter. The results of the study show that the spraying distance greatly affects the gloss value of the painted results. A distance of 15 cm results in the best gloss value of 90.94 GU with no paint defects, while a distance of 25 cm results in the lowest gloss value of 58.50 GU with rough and dull surfaces. Too close a distance increases the shine power but has the potential to cause defects in the form of  a melted clear coat  layer. This study concluded that the optimal distance for spraying clear coats is 15 cm to achieve high-quality painting results
Evaluating the Influence of Environmental Factors and Parameters on Advancements in Welding and Joining Processes: A Review Sudarno, Sudarno; Do, Quang Thang; Nubli, Haris; Prabowoputra, Dandun Mahesa; Agusti, Nur Candra Dana; Ridwan, Ridwan; Vandika, Anggi
Mekanika: Majalah Ilmiah Mekanika Vol 22, No 2 (2023): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v22i2.75378

Abstract

This review article presents a comprehensive overview of welding, including its environmental influence, common welding failures, welding parameters, and predictions of development regarding welding and corrosion. The quality and integrity of welds can be significantly affected by environmental factors such as temperature, humidity, and atmospheric contaminants. Moreover, welding failures can occur due to various reasons, such as improper welding techniques, inadequate preparation, corrosion, or material defects, leading to structural weaknesses and compromised joint integrity. Furthermore, notable progress has been achieved in welding system technology, encompassing automation, robotics, and real-time monitoring. These advancements underscore the vital role of welding parameters in transforming control, precision, and productivity within the welding process. The integration of innovative welding systems has led to improved welding efficiency, reduced human error, and increased overall process reliability. This review consolidates knowledge from diverse sources, making it a valuable resource for researchers, practitioners, and industries involved in welding.
Repair Project Acceleration Strategy of Three Ship Units using Fuzzy Logic Analysis and Critical Path Method Ubyani, Hidayatus; Tuswan, Tuswan; Yudo, Hartono; Nubli, Haris; Mursid, Ocid; Iqbal, Muhammad
Mekanika: Majalah Ilmiah Mekanika Vol 22, No 2 (2023): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v22i2.76502

Abstract

This research uses the Critical Path Method (CPM) to analyze the main schedule of three combined ship repair projects. Then, shop-level planning is used to determine the productivity of each workshop so that each workshop knows the volume of work that needs to be completed daily. Furthermore, fuzzy logic is applied to analyze the risk of delays in repair project activities. The addition of working hours to critical work activities is accelerated from 30 days, the normal duration, to 23 days. Meanwhile, the addition of the workforce to critical work activities is accelerated from 30 days, the normal duration, to 22 days. The analysis of productivity values in each workshop results in the following productivity values: sandblasting and painting workshop 309.97 m2/person-days, piping workshop 4.12 units/person-days, fabrication workshop 407.16 kg/person-days, outfitting workshop 14.8 units/person-days, tank cleaning workshop 114.36 m3/person-days, and machining workshop 2.7 units/person-days. The fuzzy logic analysis results to determine the risk of delays in critical activities show that jobs with the codes SP1, SP2, SP3, SP4, M2, and SP5 have high risk of delay. Additionally, the collaboration with other departments in the company, such as the marketing, finance, and human resources departments, is ongoing to complete assigned tasks.
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.
Numerical Analysis of Openings in Stiffeners under Impact Loading: Investigating Structural Response and Failure Behavior Ridwan, Ridwan; Sudarno, Sudarno; Nubli, Haris; Chasan, Achmad; Istanto, Iwan; Pratama, Pandu Sandi
Mekanika: Majalah Ilmiah Mekanika Vol 22, No 2 (2023): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v22i2.76774

Abstract

As the demand for lightweight ships continues to rise, there is a growing necessity to explore innovative methods that can reduce the weight of ship structures without altering the materials used. This research addresses this challenge by investigating the effect of opening in stiffener under impact loading. The research aims to provide valuable insights into optimizing weight reduction strategies while ensuring the ship's overall strength and performance remain uncompromised. To achieve this goal, the study employed the finite element method as a solver. By simulating impact scenarios and analyzing stiffener responses, the numerical analysis quantified the structural behavior and failure modes. The focus was on understanding the impact of openings on the structural integrity and how it relates to their positioning relative to the impact point. The results of the study indicate that opening slightly distant from the impact point exhibit greater strength, showcasing a counterintuitive relationship between opening placement and structural response.
Design of the Bengawan Unmanned Vehicle (UV) Roboboat: Mandakini Neo Nubli, Haris; Utomo, Fahri Setyo; Diatmaja, Hananta; Prabowo, Aditya Rio; Ubaidillah, Ubaidillah; Susilo, Didik Djoko; Wibowo, Wibowo; Muttaqie, Teguh; Laksono, Fajar Budi
Mekanika: Majalah Ilmiah Mekanika Vol 21, No 2 (2022): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v21i2.61624

Abstract

Mandakini Neo was made with the ship's capacity, speed, and comfort in mind, as well as the ship's hydrodynamic performance and construction cost. Therefore, the method used to determine the hydrostatic characteristics is through a simulation consisting of a resistance test, stability test, maneuver test, and seakeeping test. The simulation uses Maxsurf software with the Savitsky method, which is then processed by data. Global Positioning System (GPS) and ultrasonic sensor tests were also conducted. Based on the simulation results, the stability of the Mandakini Neo ship has a GZ value of 0.1417 m with an angle of 30°, which follows the standards of the International Maritime Organization (IMO). In testing, the maneuvers obtained have met IMO standards based on tactical and advanced diameters. Based on the seakeeping test, when the speed is 5 knots, the heave movement has the same magnitude for all wave headings, 0.0096 m. while the most considerable rolling motion is in the wave direction of 135°, which is 0.36 m, and the most considerable pitch motion is in the direction of the 180° wave, which is 0.042 m. At a speed of 10 knots, the heave motion produced is the same as for all wave headings.
Co-Authors Aditya Rio Prabowo Agusti, Nur Candra Dana Aldias Bahatmaka Baek, Seung Jun Chasan, Achmad Diatmaja, Hananta Didik Djoko Susilo Do, Quang Thang Fatkhurokhman, Najib Fitriyana, Deni Fajar Hartono Yudo Hidayat, Hanif Hyung, Cho Joung Istanto, Iwan Laksono, Aryo Eko Laksono, Fajar Budi Laksono, Galih Tri Muhammad Habibullah Muhammad Iqbal Muttaqie, Teguh Nur Afiqoh, Nabella Sofa Ocid Mursid Pandu Sandi Pratama Ridwan, Ridwan Singgih Dwi Prasetyo Sudarno Sudarno Trisnoaji, Yuki Tuswan Tuswan Ubaidillah Ubaidillah Ubyani, Hidayatus Utomo, Fahri Setyo Vandika, Anggi Wibowo Wibowo