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All Journal AMMA : Jurnal Pengabdian Masyarakat Journal of Mechanical Engineering and Applied Technology
Ahmad Mamba’udin
Politeknik Negeri Semarang
Humanities Automotive Engineering Chemistry Control & Systems Engineering Engineering Industrial & Manufacturing Engineering Law, Crime, Criminology & Criminal Justice Materials Science & Nanotechnology Mechanical Engineering Nursing

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Pengenalan Sistem Mesin Pesawat Bagi Siswa SMK Nasional Berbah Ahmad Mamba’udin; Elfrida Rizky Riadini; Arif Pambekti
AMMA : Jurnal Pengabdian Masyarakat Vol. 3 No. 12 : Januari (2025): AMMA : Jurnal Pengabdian Masyarakat
Publisher : CV. Multi Kreasi Media

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Abstract

This activity aims to provide students of SMK Nasional Berbah with basic insights and understanding of aircraft engines. The limited access to practical knowledge of aviation technology serves as the main rationale for implementing this program. Through this activity, students receive materials covering fundamental theories of aircraft engines, types of engines, the working principles of turbine and piston engines, as well as visual and interactive demonstration sessions. The methods used include interactive lectures, group discussions, and component introductions through video-based media. The results indicate an improvement in students' understanding of basic aircraft engine concepts and a growing interest in the field of aviation. This activity aims to spark vocational school students’ interest in aviation science.
Beyond a Single Damping Coefficient: Experimental Mapping of Nonlinear and Stroke-Dependent Automotive Shock-Absorber Behaviour Avicenna An-Nizhami; Ignatius Gunawan Widodo; Muhammad Showi Nailul Ulum; Elfrida Rizky Riadini; Ahmad Mamba’udin; Yuris Bahadur Wirawan
Journal of Mechanical Engineering and Applied Technology Vol. 4 No. 2 (2026): VOLUME 4 ISSUE 2 YEAR 2026 (JULY 2026)
Publisher : Politeknik Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32497/jmeat.v4i2.7842

Abstract

Shock absorbers are commonly represented by a constant viscous damping coefficient, although their actual force response may vary nonlinearly with piston velocity, stroke amplitude, and operating conditions. This study experimentally compared the damping characteristics of original and aftermarket rear shock absorbers using a laboratory test rig with variable-speed and variable-stroke operation. Both specimens were tested at strokes of 60, 90, and 120 mm and excitation frequencies of 0.5–2.0 Hz, corresponding to peak piston velocities of 0.0942–0.7539 m/s. Maximum damping forces were measured using a force gauge, and the resulting force–velocity relationships were evaluated before and after modification of the test rig. Three-term sinusoidal functions were also fitted to the measured data using the MATLAB Curve Fitting Tool. Both shock absorbers exhibited nonlinear digressive behaviour, characterised by a rapid force increase at low-to-intermediate velocities followed by a stroke-dependent high-speed plateau. Matched-velocity comparisons showed that damping force varied with stroke even at approximately equal peak velocities, demonstrating that the response was not governed by piston velocity alone. Using the post-modification data, the aftermarket shock absorber generated an average damping force 15.8% higher than the original unit over the complete test matrix. Its peak force exceeded that of the original shock absorber by 29.4%, 9.8%, and 12.6% at strokes of 60, 90, and 120 mm, respectively. The corresponding apparent damping coefficients were also consistently higher for the aftermarket unit. These findings demonstrate that shock-absorber performance should be evaluated using experimentally determined force–velocity operating maps across multiple strokes and velocities rather than a single nominal damping coefficient.
Co-Authors An Nizhami, Avicenna Arif Pambekti Elfrida Rizky Riadini Ignatius Gunawan Widodo Muhammad Showi Nailul Ulum Yuris Bahadur Wirawan