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All Journal Otopro Scientific Journal of Mechanical Engineering Kinematika
Yuris Bahadur Wirawan
Politeknik Negeri Semarang
Automotive Engineering Energy Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering

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SIFAT MEKANIK DAN FISIK 3D-PRINTED DENTAL PHOTOPOLYMER RESINS DALAM KONDISI PEMROSESAN YANG BERBEDA Ahmad Mamba'udin; Muhammad Akhsin Muflikhun; Adam Zuyyinal Adib; Dianisa Khoirum Sandi; Elfrida Rizky Riadini; Yuris Bahadur Wirawan
Scientific Journal of Mechanical Engineering Kinematika Vol 10 No 2 (2025): SJME Kinematika Desember 2025
Publisher : Mechanical Engineering Department, Faculty of Engineering, Universitas Lambung Mangkurat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20527/sjmekinematika.v10i2.796

Abstract

Photopolymer resins have widely applied in dentistry to fabricate temporary restorations. This work gives a complete characterization of a dental non-castable photopolymer resin prepared via Digital Light Processing (DLP) 3D printing. Specimens were printed at layer thicknesses of 0.05, 0.075, and 0.1 mm, followed by post-cured treatments under UV light for 10, 20, and 30 minutes. A series of material characterization tests were performed, including assessments of hardness, moisture absorption behavior, and density measurements. The results indicate that hardness and moisture content are significantly impacted by post-curing time, while extended curing times resulted in greater specimen’s hardness and decreased moisture content. An increase in layer thickness led to a gradual reduction in hardness. A maximum hardness value of 57.7 Shore D was observed in the 3D-printed specimen, along with a highest moisture content of 1.05% MC. As expected, the specimens exhibited consistent density (1.19 ± 0.02 g/cm³) throughout all layer thickness and curing time variations. This study highlights the critical need to understand how process parameters affect dental non-castable photopolymer resin properties prior to clinical implementation.
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.
Co-Authors Adam Zuyyinal Adib Ahmad Mamba'udin Bahtiar Rahmat Dianisa Khoirum Sandi Elfrida Rizky Riadini Fahmy Zuhda Bahtiar Irwan Setyo Prabowo Muhammad Akhsin Muflikhun