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All Journal Rekayasa Mesin Sinergi JRST (Jurnal Riset Sains dan Teknologi) PESHUM
Firdhaus, Ahmad
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Humanities Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Education Electrical & Electronics Engineering Engineering Industrial & Manufacturing Engineering Mechanical Engineering Social Sciences

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Analisis Pengaruh Multiple Repair Welding terhadap Kekuatan dan Microstructure pada Sambungan Pengelasan Baja JIS - G3101 Kiryanto, Kiryanto; Firdhaus, Ahmad; Laksana, Tri
JRST (Jurnal Riset Sains dan Teknologi) Volume 9 No. 1 Maret 2025: JRST
Publisher : Universitas Muhammadiyah Purwokerto

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30595/jrst.v9i1.21921

Abstract

Dalam industri manufaktur, proses perbaikan las yang dilakukan lebih dari satu kali (multiple repair gouging) seringkali digunakan untuk memperbaiki sambungan las yang cacat, namun proses pengelasan yang berulang dapat mengubah sifat material. Penelitian ini menggunakan sampel baja JIS - G3101 yang diperbaiki dengan variasi multiple repair gouging, diikuti dengan pengujian kekuatan tarik, kekerasan, dan analisis struktur mikro menggunakan mikroskop elektron pemindai (SEM). Hasil penelitian menunjukkan bahwa multiple repair welding mempengaruhi kekuatan tarik dan kekerasan pada sambungan las, yang tergantung pada jumlah dan kondisi pengelasan ulang. Struktur mikro juga mengalami perubahan, dengan terbentuknya fasa martensite pada zona HAZ (Heat Affected Zone) pada setiap lapisan perbaikan las. Meskipun perbaikan las dapat meningkatkan ketahanan sambungan terhadap kegagalan, hasil yang optimal dicapai dengan pengaturan prosedur pengelasan yang tepat.
The Role of Cooperative Learning in Undergraduate Engineering Education: A Better Alternative to Teacher-Centered Learning Firdhaus, Ahmad; Hakim, Muhammad Luqman; Tuswan, Tuswan; Mursid, Ocid
PESHUM : Jurnal Pendidikan, Sosial dan Humaniora Vol. 4 No. 4: Juni 2025
Publisher : CV. Ulil Albab Corp

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.56799/peshum.v4i4.9362

Abstract

This comprehensive analysis examines the effectiveness of cooperative learning (CL) in undergraduate engineering education, contrasting it with traditional teacher-centered methods. The study finds that CL enhances academic performance and develops essential skills such as critical thinking, teamwork, and communication. Unlike passive teacher-centered methods, CL promotes active participation and collaborative problem-solving, better aligning educational outcomes with the demands of the engineering profession. The article highlights the limitations of teacher-centered learning, which often fails to foster deep understanding or student engagement. CL, involving students in diverse, role-defined groups, helps them connect theory to practice, particularly benefiting first-year students transitioning into collaborative environments. However, challenges to implementing CL include student resistance, higher instructor workload, and the need for effective group management. The study stresses the importance of faculty training, discipline-specific resources, and structured support to address these obstacles. Ultimately, the article advocates for a shift toward CL in engineering education, emphasizing its potential to prepare students for collaborative, dynamic engineering roles in a technologically advanced world.
IMO-COMPLIANT ANALYSIS OF THE LARGE ANGLE STABILITY OF CHEMICAL TANKERS DURING THE LOADING AND UNLOADING LIQUID CAUSTIC SODA Firdhaus, Ahmad; Pujo, Mulyatno Imam; Luqman, Hakim Muhammad; Sekar, Wangi Nimas Ayu
Jurnal Rekayasa Mesin Vol. 14 No. 3 (2023)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/jrm.v14i3.1409

Abstract

MT. Sinar Masela 8831 DWT is a ship transporting oil and chemicals certified by IMO Chemical Class 2,3. According to Chapter B, SOLAS CHAPTER VII, regarding water safety, loading and unloading oil and chemicals is categorized as dangerous due to water damage and pollution. Various studies are needed to expedite the loading and unloading process to reduce damage and pollution in the waters. One of these studies is regarding the stability of ships in accordance with IMO criteria. The study was conducted to determine the ship stability on the MT. Sinar Masela is in the loading-unloading process. This study applies eight conditions with seven-compartment tanks on the ship using software to analyze the stability calculation when the loading-unloading process meets the stability criteria set by IMO A.749(18) Ch 3. The results show the measure of stability in eight conditions with a seven-compartment tank during the loading and unloading process has a higher GZ value in all states, which has met the IMO stability criteria. Comparison of stability calculations on loading and unloading has an average difference of 0.226 m at 2.075 deg at the GZ value in each condition.
Experimental investigation of PWHT and normalizing effects on SMAW low-carbon steel joint properties Manik, Parlindungan; Firdhaus, Ahmad; Prasetya, Blinka Hernawan; Prayoga, Rhizky
SINERGI Vol 30, No 1 (2026)
Publisher : Universitas Mercu Buana

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22441/sinergi.2026.1.009

Abstract

The influence of post-weld heat treatment (PWHT) followed by normalizing on the mechanical properties of AH36 low-carbon steel is significant, particularly in the context of marine applications, such as shipbuilding welded joints. According to the extant literature, PWHT has been demonstrated to reduce residual stresses and enhance microstructural uniformity. However, the suitable PWHT temperatures for AH36 steel welds to balance strength, ductility, and toughness prior to normalizing remain underexplored. The objective of this study is to ascertain the suitable PWHT temperatures prior to normalizing, with the aim of improving weld performance in marine environments. A parametric study was conducted on AH36 steel specimens welded using shielded metal arc welding. The specimens were subjected to PWHT at 0°C (as-welded), 450°C, 600°C, and 750°C, followed by normalizing. Tensile, bending, and Charpy impact tests were utilized to assess the mechanical properties against established maritime safety standards. The results show that 600°C is the optimal PWHT temperature, effectively reducing residual stresses and promoting microstructural homogeneity. This, in turn, ensures that welds meet safety standards while preserving mechanical integrity. Higher temperatures increased the risk of brittleness, while lower temperatures provided insufficient stress relief. This study demonstrates that precise selection of PWHT temperature prior to normalizing is critical for ensuring reliable welds in marine structures. It identifies the optimal condition that maximizes strength, ductility, and impact toughness of AH36 steel while satisfying the Indonesian Classification Bureau (BKI) maritime safety standards. 
Co-Authors Kiryanto Kiryanto Laksana, Tri Luqman, Hakim Muhammad Muhammad Luqman Hakim, Muhammad Luqman Ocid Mursid Parlindungan Manik Prasetya, Blinka Hernawan Prayoga, Rhizky Pujo, Mulyatno Imam Sekar, Wangi Nimas Ayu Tuswan Tuswan