Analisis Umur Kelelahan Struktur Kapal RoRo Terhadap Beban Gelombang Menggunakan Spectral Based Fatigue

Firmansyah, Lukman (2025) Analisis Umur Kelelahan Struktur Kapal RoRo Terhadap Beban Gelombang Menggunakan Spectral Based Fatigue. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Kelelahan struktur merupakan faktor penting yang memengaruhi umur operasional dan keselamatan kapal. Seiring bertambahnya usia, struktur kapal mengalami penurunan kekuatan akibat beban siklis dari muatan dan gelombang laut. Jika tidak diantisipasi, beban berulang dapat menimbulkan retakan pada material dan berujung pada kegagalan struktural. Usia kapal yang digunakan pada penelitian ini memiliki usia lebih dari 20 tahun sehingga diperlukan pengecekan dari segi kekuatan untuk mengetahui umur lelahnya. Untuk menghitung umur kelelahan kapal tersebut, digunakan metode spectral based fatigue yang memakai data gelombang selama 10 tahun terakhir. Analisis dilakukan pada dua kondisi pembebanan, yaitu full load dan empty load dengan mempertimbangkan delapan arah datang gelombang. Rentang frekuensi yang digunakan berada dalam kisaran 0,1 hingga 1,8 rad/s sesuai rekomendasi American Bureau of Shipping (ABS). Untuk arah datang gelombang menggunakan rentang sudut antara -180° hingga 180° dengan interval 45°. Hasil perhitungan menunjukkan bahwa umur kelelahan terhadap kondisi awal kapal pada pembebanan kombinasi, diperoleh umur kelelahan total sebesar 28 tahun. Sebagai pembanding, kondisi struktur existing dihitung dimana pada kondisi ini memperhatikan pengurangan tebal pelat yang dialami kapal akibat korosi dan menghasilkan estimasi umur kelelahan sebesar 6 tahun.
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Structural fatigue is a critical factor that influenced the operational lifespan and safety of marine vessels. Over time, a ship's structure experienced strength degradation due to cyclic loading from cargo variations and sea waves. If not properly managed, these repetitive loads could initiate and propagate cracks, ultimately leading to structural failure. The vessel under investigation had an operational age exceeding 20 years, which necessitated a thorough assessment to determine its fatigue life. To calculate this, a spectral-based fatigue analysis was employed, utilizing a decade of historical wave data. The analysis was performed for two primary loading conditions, a full load and an empty load, considering eight discrete wave headings. The wave directions were assessed in a range from -180° to 180° at 45° intervals. The frequency range used in the calculation was 0.1 to 1.8 rad/s, in accordance with recommendations from the American Bureau of Shipping (ABS). The results indicated that for the ship's initial as-designed condition under combined loadings, the total estimated fatigue life was 28 years. For comparison, the existing structural condition was also analyzed, a scenario that accounted for the reduction in plate thickness due to corrosion. This analysis yielded a significantly lower estimated fatigue life of only 6 years.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	gelombang, RoRo, spectral-based fatigue, struktur kapal, umur kelelahan, fatigue life, ship structure, wave.
Subjects:	V Naval Science > VM Naval architecture. Shipbuilding. Marine engineering
Divisions:	Faculty of Marine Technology (MARTECH) > Naval Architecture and Shipbuilding Engineering > 36201-(S1) Undergraduate Thesis
Depositing User:	Lukman Firmansyah
Date Deposited:	01 Aug 2025 00:49
Last Modified:	01 Aug 2025 00:49
URI:	http://repository.its.ac.id/id/eprint/122666

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