Analisis Umur Lelah Struktur Towing Hook Pada Tugboat Menggunakan Metode Fracture Mechanics

Rachima, Hana Bahesti (2025) Analisis Umur Lelah Struktur Towing Hook Pada Tugboat Menggunakan Metode Fracture Mechanics. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Struktur towing hook pada tugboat merupakan komponen penting yang menerima beban tarik secara berulang selama operasi penarikan barge, sehingga sangat rentan terhadap kegagalan akibat kelelahan (fatigue). Dalam penelitian ini, dilakukan analisis umur lelah struktur towing hook menggunakan pendekatan fracture mechanics untuk mengevaluasi potensi kegagalan akibat perambatan retak. Pemodelan dilakukan secara global pada struktur utama kapal dari frame 10 hingga frame 25 untuk memperoleh distribusi tegangan akibat tiga variasi kondisi beban ekstrem hasil simulasi ANSYS AQWA, yaitu beban sebesar 227.027 N, 164.014 N, dan 236.847 N. Hasil tegangan global digunakan sebagai acuan untuk pemodelan lokal dengan metode submodelling pada kupingan towing hook yang mengalami konsentrasi tegangan tertinggi. Retak dimodelkan secara arbitrary pada ujung bawah kupingan dengan retak awal sepanjang 0,5 mm. Analisis dilakukan dengan menghitung nilai Stress Intensity Factor (SIF) pada berbagai kedalaman retak dan menghitung laju perambatan retak menggunakan persamaan Paris, dengan konstanta material structural steel ASTM A36. Berdasarkan hasil analisis, umur lelah struktur towing hook pada kondisi beban 227.027 N dan ketebalan kupingan 20 mm, 22 mm dan 24 mm secara berturut-turut sebesar 37,27 tahun, 62 tahun, dan 126,88 tahun. Pada kondisi beban 164.014 N pada ketebalan 20 mm, 22 mm dan 24 mm secara berturut-turut adalah 43,06 tahun, 69,69 tahun, dan 336,36 tahun. Pada kondisi beban 236.847 N pada ketebalan 20 mm, 22 mm dan 24 mm secara berturut-turut sebesar 19,05 tahun, 29,31 tahun, dan 48,73 tahun. Dan pada koondisi pembebanan 241.584 N umur lelah pada ketebalan 20 mm, 22 mm dan 24 mm berturut-turut sebesar 13,42 tahun, 26,35 tahun dan 36,56 tahun. Hasil ini menunjukkan bahwa struktur berpotensi mengalami kegagalan dalam waktu singkat jika tidak dilakukan inspeksi rutin dan perawatan yang memadai. Penelitian ini memberikan informasi penting bagi perencanaan umur layanan towing hook dan pengambilan keputusan teknis dalam meningkatkan keselamatan operasional kapal tunda.
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The towing hook structure on a tugboat is a vital component that experiences cyclic tensile loading during barge towing operations, making it particularly vulnerable to fatigue failure. This study conducts a fatigue life assessment of the towing hook structure through a fracture mechanics-based approach to evaluate its failure risk due to crack propagation. A global finite element model of the ship’s primary structure, extending from frame 10 to frame 25, was developed to determine the stress distribution under three critical loading scenarios obtained from ANSYS AQWA simulations, with applied loads of 227,027 N, 164,014 N, and 236,847 N. The resulting global stress field was subsequently applied as a boundary condition in a local submodeling analysis focused on the towing hook lug, identified as the region with the highest stress concentration. An arbitrary crack was introduced at the lower edge of the lug with an initial length of 0.5 mm. The analysis included the calculation of the Stress Intensity Factor (SIF) at various crack depths and the prediction of crack growth rates using Paris’ law, based on material constants for ASTM A36 structural steel. The estimated fatigue life under the 227,027 N loading scenario for lug thicknesses of 20 mm, 22 mm, and 24 mm was 37.27 years, 62 years, and 126.88 years, respectively. For the 164,014 N load, the corresponding fatigue lives were 43.06 years, 69.69 years, and 336.36 years, for the 236,847 N load, they were 19.05 years, 29.31 years, and 48.73 years, while for 241,584 N load, they were 13.42 years, 26,35 years, and 36.56 years. These results suggest that premature failure may occur if routine inspection and maintenance are not adequately implemented. This study offers valuable insights for predicting the service life of towing hooks and informs engineering decisions aimed at improving the operational safety of tugboats.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	fracture mechanics, kupingan, struktur, towing hook, umur lelah, fracture mechanics, lug, structure, towing hook, fatigue life
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:	Hana Bahesti Rachima
Date Deposited:	05 Aug 2025 03:54
Last Modified:	05 Aug 2025 03:54
URI:	http://repository.its.ac.id/id/eprint/127183

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