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A. Grummy Wailanduw
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Jurusan Teknik Mesin Fakultas Teknik Universitas Negeri Surabaya Gedung A6 Kampus UNESA Ketintang Surabaya 60231 Telp. (031) 8299487, Fax. (031) 8292957
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Otopro
Published by Universitas Negeri Surabaya
ISSN : 1858411X     EISSN : 26857863     DOI : http://dx.doi.org/1026740/otopro
Core Subject : Science, Engineering,
Automotive Engineering Energy Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering
Jurnal Otopro diterbitkan 2 (dua) kali setahun yaitu bulan Mei dan November oleh Jurusan Teknik Mesin, FT-UNESA, sebagai media informasi dan forum kajian masalah ilmu Teknik Mesin. Berisi tentang tulisan ilmiah, ringkasan hasil penelitian, pembahasan kepustakaan dan gagasan kritis yang orisinil. Redaksi mengundang para ahli, praktisi, dan siapa saja yang berminat untuk menyumbangkan tulisan yang belum pernah diterbitkan dalam media cetak lain, tema tulisan meliputi: Permesinan, Konversi Energi, Material dan Metalurgi, Manufaktur, Rancang Bangun Mesin
Arjuna Subject : Teknik (semua kategori) - Teknik Mesin
Articles 6 Documents
 1 
Search results for , issue "vol 21 no 2 may 2026" : 6 Documents clear
EXPERIMENTAL STUDY ON OTTO ENGINE PERFORMANCE WITH VARIATIONS IN COMPRESSION RATIO AND GASOLINE OCTANE Bahtiar Rahmat; Irwan Setyo Prabowo; Yuris Bahadur Wirawan; Fahmy Zuhda Bahtiar
Otopro Vol 21 No 2 May 2026
Publisher : Universitas Negeri Surabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26740/otopro.v21n2.p60-68

Abstract

This research aims to analyze the effect of compression ratio variation and gasoline octane number on the performance of spark-ignition internal combustion engines. The experimental object was a single-cylinder 124 cc motorcycle engine with an original compression ratio of 9.6:1. The compression ratio was increased to 10.6:1 by reducing the cylinder height by 0.6 mm. Performance testing was carried out using a dynamometer with two types of fuel, RON 88 and RON 92. Octane number 92 was selected based on fuel availability, while octane number 88 was used to evaluate engine performance under an increased compression ratio. A cylinder wall length reduction of 0.6 mm was applied as the maximum allowable limit, beyond which cylinder head modification would be required. The performance parameters evaluated were torque and brake power over an engine speed range of 4000–7000 rpm. The results indicate that increasing the compression ratio from 9.6:1 to 10.6:1 improved engine torque and brake power by approximately 3.8% to 4%. Meanwhile, the use of higher-octane gasoline (RON 92) increased performance by only about 2% to 2.4%, and only when used in the higher compression engine. In contrast, using high-octane fuel in a low-compression engine resulted in reduced performance due to ignition delay. Overall, the optimal performance was achieved when a high compression ratio was paired with high-octane fuel. Therefore, selecting an appropriate octane rating according to the engine compression ratio is essential to achieve optimal combustion efficiency, brake power output, and torque response.
SIMULATION OF FATIGUE AND DEFORMATION OF CARBON FIBER DRONE PROPELLERS USING THE FINITE ELEMENT METHOD (FEM) Syaiful Arif
Otopro Vol 21 No 2 May 2026
Publisher : Universitas Negeri Surabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26740/otopro.v21n2.p51-59

Abstract

This study analyses finite elements in the structural calculation of a drone propeller in carbon fiber with loads that represent live use. The output of this study evaluates the effect of load variations on deformation, stress distribution, and safety factors as key indicators of structural performance. A three-dimensional propeller model is developed based on the actual geometric configuration and analysed using the Finite Element Method (FEM). Several loadings are considered: a base load with a total mass of 3.6 kg, and two additional loading conditions with increasing masses of 0.5kg and 0.75kg. The applied loads are converted into equivalent forces distributed along the propeller blades to simulate realistic operating conditions. Simulations show that increasing the applied load causes a proportional increase in the maximum deformation and a significant reduction in the minimum safety factor. The maximum deformation increases from 14.933mm at the base load to 18.044mm at the highest load. The blade tip is consistently identified as a critical region, where the highest deformation and stress concentration occur due to bending-dominated behaviour. The safety factor ranges from 0.51341 to 0.42489 as the load increases, indicating a decrease in structural safety. Fatigue loading is mentioned, this study addresses fatigue qualitatively based on stress concentration and safety factor trends, as explicit S–N curve data, load cycle definitions, and mean stress corrections are not included. The results emphasize the importance of structural optimization and accurate material modelling to improve the reliability and durability of carbon fiber drone propellers under various load conditions.
DESIGN OF A LIFTER FOR HORIZONTAL CHAMBER MACHINE IN A LEAF SPRING PRODUCTION LINE: A CASE STUDY AT PT. XYZ Ahmad Saepuddin; Rachman Arya Syahputra
Otopro Vol 21 No 2 May 2026
Publisher : Universitas Negeri Surabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26740/otopro.v21n2.p69-77

Abstract

PT. XYZ is an automotive manufacturing company that produces leaf springs. One of the machines used in the leaf spring forming process is a Horizontal Chamber Machine that works by pressing. In its operation, this machine requires a lifter to assist in the transfer of leaf springs and reduce the risk of workplace accidents. The lifter has a frame component that functions as the main structure in supporting the load during the lifting and lowering of the leaf spring. Therefore, it is necessary to design a lifter frame that is safe and capable of withstanding the working load that occurs during the production process. This study aims to design and evaluate the strength of the lifter frame to ensure its safety in operational use. There are three variations of frame designs differentiated by material thickness, namely 10 mm, 12 mm, and 14 mm. The simulation results show that the maximum stress in frame design 1 is 24 MPa, frame design 2 is 16 MPa, and frame design 3 is 12 MPa. The strain values for each design are 0.000066, 0.000048, and 0.000036, while the displacement maximum values are 0.026 mm, 0.016 mm, and 0.016 mm. The safety factors obtained are 11, 15, and 19, respectively. The fatigue life value for all frame designs is  cycles. Based on these simulation results, frame design 1 is declared to have met the strength and safety criteria required for use in the production process
EFFECT OF SECTION THICKNESS ON NODULAR GRAPHITE FORMATION AND MECHANICAL PROPERTIES OF DUCTILE CAST IRON Moch Chamim; Edi Sarwono; Haikal Haikal; Margono Margono
Otopro Vol 21 No 2 May 2026
Publisher : Universitas Negeri Surabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26740/otopro.v21n2.p43-50

Abstract

This study investigates the effect of section thickness on the microstructure and mechanical response of Ductile Cast Iron (DCI) using specimens with thicknesses of specimen 20, 40, and 60 mm. Optical microscopy reveals a ferrite-pearlite matrix with spherical graphite, where the graphite nodules exhibit a tendency toward larger size and greater heterogeneity with increasing section thickness. The measured nodule diameters are approximately 17-20 µm (20 mm), 21-22 µm (40 mm), and 15-26 µm (60 mm), indicating thickness-driven changes in solidification/cooling conditions that promote graphite hardening in thicker sections. Mechanical testing shows a consistent decrease in hardness with increasing thickness: 246.8 VHN (specimen 20 mm), 226.75 VHN (specimen 40 mm), and 204.8 VHN (specimen 60 mm). Impact test results show a non-monotonic trend, increasing from 0.02 (specimen 20 mm) to 0.049 (specimen 40 mm) and slightly decreasing to 0.045 (specimen 60 mm). The highest impact value at specimen 40 mm indicates an optimal balance between matrix hardness and toughness at intermediate thicknesses, while the slight decrease at specimen 60 mm despite the lower hardness may be related to increased graphite size heterogeneity and microstructural nonuniformity in thicker sections. Overall, thickness significantly affects graphite morphology and the hardness toughness trade off in DCI, with 40 mm sections providing the most favorable toughness in this data set.
EVALUATION OF INJECTION MOLDING PROCESS PARAMETERS ON THE QUALITY OF BRAKE FLUID RESERVOIR CAP PRODUCTS USING MOLDFLOW SIMULATION Adinda Rahmah Shalihah; Aditya Bagja Subarkah; Farras Novyansyah; Irfan Fadillah; Ammar Fathi Muhadzab; Hafizh Maulana Alfath; Ulima Adristi Azis; Hikari Qurrata’ain Nurhadi
Otopro Vol 21 No 2 May 2026
Publisher : Universitas Negeri Surabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26740/otopro.v21n2.p78-84

Abstract

This study aims to analyze the effect of melt temperature and mold surface temperature variations on the quality of the motorcycle brake fluid reservoir cap using Autodesk Fusion simulation. Three parameter variations were applied: 260°C/80°C, 220°C/50°C, and 180°C/20°C, while other process parameters were kept constant. The evaluation focused on fill confidence, weld lines, sink marks, and warpage. The results show that all conditions achieved 100% fill confidence with a filling time of 0.53 seconds. However, higher temperatures reduced weld lines but increased sink marks and warpage. Conversely, lower temperatures minimized deformation but increased the number of visual defects. The medium temperature condition provided the best balance between visual quality and dimensional stability. Therefore, the 220°C/50°C condition is recommended as optimal
NUMERICAL INVESTIGATION OF REAR WINDSHIELD ANGLE AND REYNOLDS NUMBER EFFECTS ON THE AERODYNAMIC PERFORMANCE OF A SALOON CAR Dwi Tarti; Ika Nurjannah; Herman Sasongko
Otopro Vol 21 No 2 May 2026
Publisher : Universitas Negeri Surabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26740/otopro.v21n2.p85-94

Abstract

This study examined how rear windshield angle and body geometry affect the aerodynamic behavior of a saloon car model using numerical simulations. Rear windshield angles of 45°, 60°, 75°, and 90° were considered for two configurations—sharp and rounded rear corners— whereas the front windshield angle was kept constant at 30% to allow a consistent comparison. Simulations were conducted at two Reynolds numbers, 6.5×10⁶ and 11.8×10⁶, corresponding to inlet velocities of 22.2m/s and 40m/s. The simulations were performed using ANSYS Fluent 2024, focusing on the flow behavior along the upper and lower surfaces, as well as the resulting drag and lift characteristics. The results showed that increasing the rear windshield angle generally led to higher drag, mainly due to the expansion of the wake region behind the vehicle. Models with rounded corners consistently performed better than sharp-edged ones, producing lower drag and more stable flow behavior. The lowest drag coefficient (CD=0.556) was found for the rounded configuration at a 45° rear windshield angle, whereas the highest value (CD=0.8147) appeared in the sharp configuration at 90°. From the flow visualization, it can be seen that the sharp edges create stronger adverse pressure gradients, which trigger earlier separation and lead to a larger wake. In contrast, rounded corners helped the flow to recover more smoothly and delayed separation. Overall, these findings emphasize the role of the rear windshield angle and body geometry in improving aerodynamic efficiency and minimizing energy losses.

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