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All Journal Department of Naval Architecture Rekayasa Mesin Jurnal Rekayasa Mesin Journal of Mechanical Engineering Science and Technology SELAPARANG: Jurnal Pengabdian Masyarakat Berkemajuan Angkasa: Jurnal Ilmiah Bidang Teknologi KACANEGARA Jurnal Pengabdian pada Masyarakat Mekanika: Majalah Ilmiah Mekanika Janaka : Jurnal Pengabdian Masyarakat Jurnal Pendidikan dan Teknologi Indonesia Jurnal Ilmiah Wahana Pendidikan Society: Jurnal Pengabdian Masyarakat Jurnal Vokasi Mekanika Jurnal Rekayasa elektrika Advance Sustainable Science, Engineering and Technology (ASSET) Jurnal Abdimas Taawun: Jurnal Pengabdian kepada Masyarakat Rekayasa: Jurnal Penerapan Teknologi dan Pembelajaran Jurnal Inovasi Mesin Jurnal Panjar : Pengabdian Bidang Pembelajaran
Aldias Bahatmaka
Universitas Negeri Semarang
Religion Agriculture, Biological Sciences & Forestry Humanities Chemistry Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Economics, Econometrics & Finance Education Electrical & Electronics Engineering Energy Engineering Environmental Science Health Professions Industrial & Manufacturing Engineering Languange, Linguistic, Communication & Media Law, Crime, Criminology & Criminal Justice Materials Science & Nanotechnology Mechanical Engineering Medicine & Pharmacology Nursing Public Health Social Sciences Other

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Effect of Printing Speed on the Properties of 3D Printed Products Using Recycled PET Filament Deni Fajar Fitriyana; Agung Efriyo Hadi; Nugroho Suhodo; Aldias Bahatmaka; Januar Parlaungan Siregar; Tezara Cionita; Zuhriyan Ash Shiddieqy Bahlawan; Achmad Yanuar Maulana
Advance Sustainable Science Engineering and Technology Vol. 8 No. 3 (2026): May - July
Publisher : Science and Technology Research Centre Universitas PGRI Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26877/asset.v8i3.2049

Abstract

Recycled PET has been widely studied for its potential use in 3D printing applications. However, few research has examined how printing speed affects recycled PET filament products' mechanical and physical qualities. This research examines how printing speed influences the physical and mechanical qualities of 3D-printed PET filament goods created from mineral water bottle trash. In this study, filament fabrication is carried out using the homemade pultrusion machine, then the filament is used for 3D printing with variations in printing speed (30, 45, and 60 mm/s). The conducted tests comprise density, tensile, hardness, and compressive testing to examine their physical and mechanical properties. This research found that 45 mm/s printing produced specimens with the maximum density, tensile strength, and hardness. The material reached a density of 0.968 g/cm³, tensile strength of 15.752 N/mm², and hardness of 43.50 Shore D under these circumstances. In contrast, specimens printed at 30 mm/s and 45 mm/s showed the greatest (10.841 N/mm²) and lowest (6.510 N/mm²) compressive strengths. The density, hardness, and tensile strength of 3D-printed specimens improved as the printing speed increased from 30 to 45 mm/s. Printing rates above 45 mm/s reduced specimen density, hardness, and tensile strength. This work promotes sustainable manufacturing by showing that recycled PET filament may be used for 3D printing and how printing speed affects material qualities, thereby promoting sustainable production practices and reduce dependence on virgin materials.
The Analysis of Diameter Expansion and Connection Angle Variations Effects In Hyropower Penstock Pipe Bend on Pressure Drop Using Computational Fluid Dynamics Simulation Agung Widodo; Dony Hidayat Al-Janan; Aldias Bahatmaka
Jurnal Vokasi Mekanika (VoMek) Vol 8 No 2 (2026): Jurnal Vokasi Mekanika
Publisher : Unversitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/wb52b413

Abstract

Pembangkit Listrik Tenaga Air (PLTA) memanfaatkan pipa pesat (penstock) sebagai saluran utama pengaliran air dari reservoir menuju rumah pembangkit. Belokan pada jalur pipa pesat berpotensi menyebabkan pressure drop yang dapat menurunkan efisiensi sistem secara keseluruhan. Penelitian ini bertujuan untuk menganalisis pengaruh variasi perbesaran diameter dan variasi sudut penghubung pada belokan pipa terhadap nilai pressure drop. Kajian teoritis  yang digunakan meliputi prinsip persamaan kontinuitas dan persamaan bernoulli dalam sistem perpipaan. Penelitian ini menggunakan pendekatan kuantitatif dengan metode eksperimen berbasis simulasi Computational Fluid Dynamics (CFD) menggunakan perangkat lunak ANSYS Fluent 2019 R3. Pengambilan data dilakukan menggunakan simulasi numerik numerik terhadap 13 variasi desain belokan pipa yang mencakup variasi perbesaran diameter 1D, 1,25D dan 1,5D dengan variasi sudut penghubung 10°, 20°, 30°, 45°, 60° dan 90°, menggunakan model turbulensi k-epsilon realizable dengan kecepatan inlet 7 m/s. Hasil simulasi menunjukkan bahwa nilai pressure drop dipengaruhi secara signifikan oleh kedua variabel. Semakin kecil sudut penghubung, semakin rendah nilai pressure drop yang dihasilkan, dengan peningkatan sudut dari 10° ke 90° menyebabkan kenaikan pressure drop sebesar 898,0% pada variasi 1,25D dan 1.707,9% pada variasi 1,5D. Perbesaran diameter efektif menurunkan pressure drop hanya pada sudut penghubung kecil, sedangkan pada sudut besar justru memicu separasi aliran dan zona resirkulasi. Desain paling optimal adalah 1,25D dengan sudut penghubung 10°, yang menghasilkan pressure drop sebesar 1.094,350 Pa atau lebih rendah 47,7% dibandingkan desain standar 1D. Penelitian ini memberikan rekomendasi desain belokan pipa pesat yang mampu meminimalkan kerugian tekanan guna meningkatkan efisiensi sistem PLTA. 
Analysis of Variations in Bow Design and Vessel Speed on the Response Amplitude Operator (RAO) of a Crew Boat Using Computational Fluid Dynamics (CFD) Kirana, Arnova Chandra Cahya; Bahatmaka, Aldias; Malsyage, Dina; Cho, Joung Hyung; Ttum, Seo Ou
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.v24i2.106779

Abstract

The performance and stability of crew boats in dynamic maritime environments are significantly influenced by hull geometry, particularly the design of the bow. This study investigates the influence of various elliptical bulbous bow configurations and vessel speeds on the Response Amplitude Operator (RAO) in heave and pitch motions. Using Computational Fluid Dynamics (CFD) simulations via ANSYS AQWA, four bow configurations, including a bare hull and three bulbous bow variants, were analyzed at speeds of 6, 12, and 18 knots under regular wave conditions defined by the Joint North Sea Wave Project (JONSWAP) spectrum. To validate the accuracy and reliability of the simulation method employed in this study, a comprehensive validation procedure was undertaken. For heave motion, the RAO deviation was 3.71%, and for pitch, 4.59%, both within acceptable CFD validation standards. Results indicate a minimal impact at lower speeds; however, at 18 knots, Bow 3 achieved the most significant reduction in RAO, with reductions of up to 9% in heave and 22.4% in pitch. These findings confirm the importance of optimized bow geometry in enhancing seakeeping performance.
Numerical Analysis of Six Degrees of Freedom Motion Response of Trimaran Semi-Submersible Ship Putrananda, Musdika Bagas Satria; Bahatmaka, Aldias; Aryadi, Widya; Puteri, Berliana Ayarent; Hutagalung, Christian Imanuel
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.v24i1.99057

Abstract

This study examines the motion response characteristics of a trimaran semi-submersible vessel, with a focus on its performance in tourism applications where passenger comfort is a primary concern. Using ANSYS AQWA simulation software, this analysis integrates diffraction and radiation theory with potential flow theory to evaluate the six degrees of freedom (surge, sway, heave, roll, pitch, and yaw) under various wave conditions, including different frequencies and directions based on the Joint North Sea Wave Project (JONSWAP) spectrum. Simulations were performed on waves with heading angles ranging from 0° to 180°. The simulation results were validated based on previous studies both experimentally and numerically. The results show that the sway peaks at 8 m/m for heading angles of 90°, while the surge reaches a maximum of 8 m/m at 0° and 180°. The heave motion resonates between 2.2 rad/s with a peak amplitude of 3 m/m at 90°. Pitch motion at heading angles of 0° reaches 40 °/m at 3.5-4 rad/s. Roll motion remained within acceptable limits (9 °/m), and yaw peaked at 13 °/m at 45° and 135°. These findings suggest that, although the trimaran exhibits stable performance in most motion responses, design improvements are necessary to mitigate excessive pitch motion and enhance passenger comfort in tourism 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.
Performance Analysis of the Fast Platform Supply Vessel with a Conventional V-Hull Shape with the Addition of a Chine and a Different Bow Using Computational Fluid Dynamics Method Rumapea, Fedrik Immanuel; Bahatmaka, Aldias; Hamizan, Banin; Rahardian, Pramudya; Rantisi, Umar Zaid; Kurniaputri, Dias Fitria
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.v25i1.114601

Abstract

Indonesia is the largest country in Southeast Asia, consisting of more than 17,000 islands and a coastline of approximately 81,000 kilometers, with over half of its territory covered by water. To optimize this vast marine potential for public welfare, comprehensive data collection and mapping are essential. The oil and gas sector remains a key contributor to national revenue. For instance, Pertamina Hulu East Kalimantan (PHKT) exceeded its 2023 production target, achieving around 9,900 barrels of oil and 45 million cubic feet of gas per day. To support offshore operations, a Platform Supply Vessel (PSV) prototype named Bramantya was designed. This study analyzes the vessel using Computational Fluid Dynamics (CFD) to determine the optimal hull form for operational performance and fuel efficiency. Three hull variations were examined: a conventional hull, a hull with additional chines, and a wide-bow hull. The simulation was validated against previous experimental studies, showing consistent linear results with an average error of 4.25%. Simulations at Froude numbers 0.2–0.6 show that the wide downward-bowed hull reduces drag by 7.69% compared to the conventional hull, thereby improving fuel efficiency.
Analytical Review of Numerical Analysis in Hydrodynamic Performance of the Ship: Effect to Hull-Form Modifications Bahatmaka, Aldias; Fitriyana, Deni Fajar; Anis, Samsudin; Maulana, Achmad Yanuar; Tamamadin, Mamad; Lee, Sang Won; Cho, Joung Hyoung
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.v23i1.83635

Abstract

This review paper provides an overview of simulation-based hydrodynamic design optimization for ship hull forms. It also includes a numerical analysis aimed at accomplish early-stage simulation-based design in terms of hydrodynamic performance. A hydrodynamic module, a hull surface modeling module, and an optimization module are the primary components of this numerical analysis. The hydrodynamic module includes both simple design approaches and high-fidelity numeric tools; these integrated tools are used to evaluate hydrodynamic performances at different design stages. The hull surface modeling module offers a variety of techniques for ship hull surface representation and modification. It is also used to automatically create hull forms or change existing hull forms based on hydrodynamic performance and design constraints. The optimization module includes several optimization algorithms and surrogate models used to determine optimal designs in terms of hydrodynamic performance. Numerical findings indicate that the current tool is well suited for hull form design optimization at the early design stage because it can produce effective optimal designs within a short time.
Analysis of Stern Flap Application on Planing Hulls to Reduce Resistance Using CFD Hidayat, Indra Nurul; Bahatmaka, Aldias; Rumapea, Fedrik Immanuel; Exada, Dandi
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.v25i1.114603

Abstract

Planing hulls exhibit complex hydrodynamic characteristics at high speeds due to two-phase flow interactions, variations in wetted surface area, and nonlinear pressure distributions, making resistance prediction challenging. This study evaluates the effect of stern flap angle and span width on the total resistance of a planing hull under calm-water conditions. Numerical simulations were conducted using a Reynolds-Averaged Navier–Stokes (RANS)-based Computational Fluid Dynamics approach with a k–ε turbulence model and the Volume of Fluid (VOF) method in ANSYS Fluent. The numerical model was validated against a benchmark CFD study previously verified with Fridsma's experimental data, showing deviations below 5% across the investigated Froude number range. Parametric simulations were performed for stern flap angles of 2°, 4°, and 6° with span widths of 43%, 48%, and 53% of the hull breadth. The results indicate that stern flap configuration significantly affects resistance, particularly under full planing conditions. The optimal configuration was obtained at a span of 53% of the hull breadth with a 2° flap angle, reducing the non-dimensional resistance (R/Δ) from 0.186 to 0.1699 (9.69%) at Fr = 1.8. Trim analysis shows an average reduction of 1.16°, contributing to the observed decrease in resistance.
Co-Authors Abdurrahman Abdurrahman Achmad Yanuar Maulana Agung Efriyo Hadi Agung Widodo Agustinus Purna Irawan Andi Abdullah Ghyferi Andriano, Kriswanto Anindya Ardiansari Antama Bahatmaka, Antama Anwar, Ahmad Ari Dwi Nur Indriawan Musyono Arimaz Hangga, Arimaz Arrijah, Hanalinda Kubrus Asri, Sarwi Azara, Salsa Bila Bahlawan, Zuhriyan Ash Shiddieqy Buana, Lanang Puspa Budi Arif Prabowo, Setya Budi Darsono, Febri Budi Chasan, Ahmad Cho, Joung Hyoung Cho, Joung Hyung Cionita, Tezara Darsono, Febri Budi Didik Supriadi Dony Hidayat Al-Janan Eko Sasmito Hadi Exada, Dandi Fahmi, Fiqri Fadillah Fidia Fibriana Fiqri Fadillah Fahmi Fitriana, Deni Fajar Fitriyana, Deni Fajar Ghyferi, Andi Abdullah Godham Eko Saputro Hamizan, Banin Hanif Hidayat Hee, Song Yeon Hendrix Noviyanto Firmansyah, Hendrix Noviyanto Herlin Pujiarti Hidayat, Hanif Hidayat, Indra Nurul Hilmi Farras, Muhammad Hutagalung, Christian Imanuel Hyoung Cho, Joung Hyung, Cho Joung Imam Pujo Mulyatno Imanu Danar Herunandi Irawaty Irawaty Irawaty Iskandar, Ranu Januar Parlaungan Siregar Karnowo - Khoirul Huda Kirana, Arnova Chandra Cahya Kriswanto Kriswanto, Kriswanto Kurniaputri, Dias Fitria Kurniawan, Ahmad Khusom Kusuma, Anwar Widjaya Laksono, Aryo Laksono, Aryo Eko Laksono, Galih Tri Lee, Sang Won Leksono, Panggah Bowo Malsyage, Dina Mamad Tamamadin Manalu, Janviter Markus Diantoro Maulana, Achmad Yanuar Mayangsari , Effelie Dewi Mera Kartika Delimayanti Muclisin, Choirul Anton Muhammad Habibullah Muhammad Khumaedi Muhammad Yusuf Wibowo Natalia Desy Putriningtyas, Natalia Desy Nubli, Haris Nugroho Suhodo Prasdika, Tegar Oki Puspitasari, Windy Desti Puteri, Berliana Ayarent Putrananda , Musdika Bagas Satria Putrananda, Musdika Bagas Satria Rafif Dimas Pratama Rahardian, Pramudya Ramadhani, Risky Rantisi, Umar Zaid Retnaningsih, Prihatini Ridananda, Ayyub Rizki Setiadi Rizqi Fitri Naryanto Rumapea, Fedrik Immanuel Rumondang, Juwita Ria Rusiyanto Rusiyanto, Rusiyanto Salim, Nur Azis Samsudin Anis Sandi Pratama , Fajar Rizqi Sang Won, Lee Sanggrahita, Diadora Sari, Linda Setiadi, Rizki Siregar, Januar Parlaungan Sonika Maulana Sucihatiningsih Dian Wisika Prajanti Sukoco, Imam Sunyoto Sunyoto Supriadi, Didik Sutrisno, Deyndrawan Syafei, M. Hilman Gumelar Tezara Cionita Ttum, Seo Ou Vandika, Anggi Wara Dyah Pita Rengga Warsiti Warsiti Warsiti Warsiti Wibowo, Muhammad Yusuf Widya Aryadi Widya Hary Cahyati Winarko, Chandra Adi Won, Lee Sang Yunus, Elfandy