Analisis Umur Lelah Pada Konversi Kapal Tongkang Menjadi Floating Dock Menggunakan Metode Elemen Hingga

Ibrahim, Muhammad Alfan (2026) Analisis Umur Lelah Pada Konversi Kapal Tongkang Menjadi Floating Dock Menggunakan Metode Elemen Hingga. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Penelitian ini melakukan pemodelan struktur tongkang hasil konversi menjadi floating dock menggunakan metode elemen hingga (Finite Element Method) untuk memperoleh distribusi tegangan siklik dan mengidentifikasi titik-titik kritis yang berpotensi mengalami kegagalan fatigue. Evaluasi ketahanan struktur terhadap beban berulang (cyclic loading) dilakukan melalui Fatigue Design Assessment (FDA) berbasis metodologi kurva S-N sesuai BKI Vol. II Section 20, dengan pendekatan simplified fatigue assessment menggunakan kaidah Palmgren-Miner, sehingga diperoleh prediksi ketahanan jangka panjang struktur terhadap pembebanan operasional. Tinjauan dilakukan pada dua level analisis, yaitu tegangan global pada penampang midship dan tegangan lokal pada detail sambungan bracket di tiga area kritis. Ketiga kondisi pembebanan operasional yang dianalisis meliputi kondisi floating, Immersing, dan working, dengan rentang tegangan (Δσ) dihitung sebagai selisih tegangan maksimum dan minimum yang terjadi di antara ketiga kondisi tersebut pada tiap titik kritis. Hasil analisis fatigue global pada sepuluh titik sambungan pelat di area midship menunjukkan umur lelah terpendek sebesar 74407.96 tahun pada posisi top deck, dengan rasio kerusakan kumulatif (D) maksimum sebesar 0.000269 jauh di bawah batas izin 1,0. Pada analisis fatigue lokal, titik paling kritis berada pada Bracket fr 13 bottom Area 2 (Node 1609) dengan rentang tegangan Δσ = 156.13 MPa, D = 0.011269, dan umur lelah Tf = 1.774,78 tahun, atau sekitar 88 kali lipat umur desain 20 tahun. Seluruh titik kritis pada kedua level analisis dinyatakan aman terhadap kegagalan akibat kelelahan. Kondisi penentu (governing) kelelahan struktur berada pada detail sambungan bracket, bukan pada pelat midship, yang konsisten dengan karakteristik umum struktur dok apung. Hasil penelitian ini diharapkan menjadi pedoman evaluasi desain dan referensi teknis dalam proses konversi kapal tongkang menjadi floating dock, sehingga struktur yang dihasilkan aman, andal, serta memenuhi persyaratan klasifikasi.
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This study investigates the structural analysis of a converted barge into a floating dock using the Finite Element Method (FEM) to obtain cyclic stress distribution and identify critical points susceptible to fatigue failure. The structural resistance against cyclic loading is evaluated through Fatigue Design Assessment (FDA) based on the S-N curve methodology in accordance with BKI Vol. II Section 20, employing a simplified fatigue assessment approach with the Palmgren-Miner cumulative damage rule, thereby yielding long-term structural durability predictions under operational loading.The analysis is conducted at two levels: global stress assessment at the midship cross-Section and local stress assessment at bracket connection details across three critical areas. Three operational loading conditions are considered floating, Immersing, and working with the stress range (Δσ) defined as the difference between the maximum and minimum stresses occurring among the three conditions at each critical point.Global fatigue results at ten plate connection points in the midship and bulkhead vicinity indicate a minimum fatigue life of 74,407.96 years at the top deck position, with a maximum cumulative damage ratio (D) of 0.000269 well below the allowable limit of 1.0. For the local fatigue assessment, the most critical point is identified at Bracket fr 13 bottom Area 2 (Node 1609), with a stress range of Δσ = 156.13 MPa, D = 0.011269, and a fatigue life of Tf = 1,774.78 years, approximately 88 times the design life of 20 years. All critical points at both assessment levels are declared safe against fatigue failure. The governing fatigue condition is found at the bracket connection details rather than the midship plating, which is consistent with the general behaviour of floating dock structures. The findings of this study are intended to serve as a design evaluation guideline and technical reference for the conversion of barges into floating docks, ensuring that the resulting structure is safe, reliable, and compliant with classification requirements.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Floating dock, finite element method, fatigue, BKI, simplified fatigue assessment, Palmgren-Miner, kurva S-N ======================================================== floating dock, fatigue, finite element method, BKI, simplified fatigue assessment, Palmgren-Miner, S-N curve
Subjects:	V Naval Science > VM Naval architecture. Shipbuilding. Marine engineering V Naval Science > VM Naval architecture. Shipbuilding. Marine engineering > VM163 Hulls (Naval architecture) V Naval Science > VM Naval architecture. Shipbuilding. Marine engineering > VM297 Ships Designs and drawings
Divisions:	Faculty of Marine Technology (MARTECH) > Naval Architecture and Shipbuilding Engineering > 36201-(S1) Undergraduate Thesis
Depositing User:	Muhammad Alfan Ibrahim
Date Deposited:	06 Aug 2026 08:03
Last Modified:	06 Aug 2026 08:03
URI:	http://repository.its.ac.id/id/eprint/144084

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