RAMADHAN, MUHAMMAD KHARISMA (2026) ANALISIS PENGARUH COLD WORKING EXPANSION PROCESS PADA FASTENER HOLE SAMBUNGAN RANGKA FRAME 40 PESAWAT AIRBUS A330. S1 thesis, Universitas Mercu Buana Jakarta.
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Abstract
Structural failures around fastener holes in aircraft fuselage joints have become a critical concern in aviation, as evidenced by cases such as Southwest Airlines Flight 812 (2011) and Aloha Airlines (1988). Fastener holes in skin-to-frame joints act as stress concentration points where the local stress can reach up to three times the nominal working stress, potentially initiating fatigue cracks. To mitigate this risk, a prestressing method known as the split sleeve cold working expansion hole process is applied to generate compressive residual stress around the hole. This study aims to analyze the effect of the cold working expansion process on the mechanical properties and microstructural changes of aluminum 7075 T6 (0.07 in) and 7075 T3 (0.04 in), representing the material used in the Frame 40 joint of the Airbus A330. An experimental method was employed by comparing specimens before and after the cold working process, followed by micro vickers hardness testing and microstructural observation using a digital optical microscope. The results show that the average hardness of aluminum 7075 T6 increased from 182.59 HV to 204.7 HV (an increase of 12%), while aluminum 7075 T3 increased from 40.11 HV to 46.78 HV (an increase of 16.5%). Microstructural observations reveal a denser structure, increased dislocation density, and the formation of deformation bands after the cold working process. These findings confirm that cold working expansion effectively enhances the local mechanical strength around fastener holes and has the potential to extend the fatigue life of aircraft structures. Keywords: cold working expansion, fastener hole, aluminum 7075, micro ickers hardness, microstructure, fatigue. Kegagalan struktur pada sambungan fuselage pesawat akibat retakan di sekitar lubang fastener telah menjadi perhatian serius dalam dunia aviasi, seperti yang terjadi pada kasus Southwest Airlines Flight 812 (2011) dan Aloha Airlines (1988). Lubang fastener pada sambungan skin dan frame pesawat merupakan titik konsentrasi tegangan yang dapat mencapai tiga kali tegangan kerja, sehingga berpotensi memicu inisiasi retak lelah. Untuk mengurangi risiko tersebut, dikembangkan metode prestressing melalui proses split sleeve cold working expansion hole yang bertujuan menghasilkan tegangan sisa tekan (compressive residual stress) di sekitar lubang. Penelitian ini bertujuan menganalisis pengaruh proses cold working expansion terhadap sifat mekanik dan perubahan struktur mikro pada material aluminium 7075 T6 (0,07 in) dan 7075 T3 (0,04 in) yang merepresentasikan material pada sambungan rangka frame 40 pesawat Airbus A330. Metode penelitian yang digunakan adalah eksperimental dengan membandingkan sampel sebelum dan sesudah proses cold working, kemudian dilakukan pengujian micro vickers hardness dan pengamatan struktur mikro menggunakan digital optical microscope. Hasil penelitian menunjukkan bahwa pada aluminium 7075 T6 terjadi peningkatan kekerasan rata-rata dari 182,59 HV menjadi 204,7 HV (naik 12%), sedangkan pada aluminium 7075 T3 meningkat dari 40,11 HV menjadi 46,78 HV (naik 16,5%). Pengamatan mikrostruktur memperlihatkan pemadatan struktur, peningkatan kepadatan dislokasi, dan munculnya deformation bands setelah proses cold working. Temuan ini membuktikan bahwa cold working expansion efektif meningkatkan kekuatan lokal material di sekitar lubang fastener yang berpotensi memperpanjang fatigue life struktur pesawat. Kata kunci: cold working expansion, fastener hole, aluminium 7075, micro vickers hardness, struktur mikro.
| Item Type: | Thesis (S1) |
|---|---|
| NIM/NIDN Creators: | 41324110032 |
| Uncontrolled Keywords: | cold working expansion, fastener hole, aluminium 7075, micro vickers hardness, struktur mikro. |
| Subjects: | 600 Technology/Teknologi > 620 Engineering and Applied Operations/Ilmu Teknik dan operasi Terapan > 621 Applied Physics/Fisika terapan > 621.8 Machine Engineering, Machinery/Teknik Mesin 600 Technology/Teknologi > 670 Manufacturing/Manufaktur, Pabrik-pabrik > 671 Metalworking Process/Pabrik Logam > 671.3 Mechanical Working and Related Process/Proses Kerja Mekanik dan Proses yang Berhubungan 700 Arts/Seni, Seni Rupa, Kesenian > 720 Architecture/Arsitektur > 729 Design and decoration of Structures/Desain dan Pola Bangunan > 729.1 Design in Vertical Plane/Desain Pesawat Vertikal |
| Divisions: | Fakultas Teknik > Teknik Mesin |
| Depositing User: | khalimah |
| Date Deposited: | 05 Mar 2026 03:56 |
| Last Modified: | 05 Mar 2026 03:56 |
| URI: | http://repository.mercubuana.ac.id/id/eprint/101372 |
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