Analisis Umur Lelah Kapal Akibat Perambatan Retak Pada Bracket Ruang Muat

Putera, Fardhan Jaya (2024) Analisis Umur Lelah Kapal Akibat Perambatan Retak Pada Bracket Ruang Muat. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Kegagalan struktural seperti kelelahan (fatigue) dapat menyebabkan keretakan pada kapal. Ketika suatu struktur mencapai batas umur kelelahannya, struktur akan mengalami initial crack hingga akhirnya struktur mengalami fracture. Pada kapal tanker, kelelahan struktural sering terjadi pada area-area kritis seperti pada sambungan bracket inner bottom dengan hopper sloping plate (end bracket). Pada penelitian ini digunakan tiga variasi ketebalan end bracket, yaitu 12 mm, 14 mm, dan 16 mm. Analisis umur lelah kapal dilakukan dengan bantuan software finite element. Di mana perhitungan pembebanan dan pemodelan mengacu pada Common Structural Rules for Double Hull Oil Tankers (CSR-T). Untuk pembebanan pada model global menggunakan beban sloshing muatan tangki (beban internal). Sedangkan pemodelan global pada software finite element menggunakan tiga kompartemen ruang muat dengan end bracket sebagai model lokal. Dari hasil analisis model global dengan metode elemen hingga, diperoleh nilai tegangan normal maksimum pada area end bracket. Selanjutnya nilai tegangan dari hasil analisis model global digunakan untuk analisis model lokal. Hasil analisis model lokal berupa nilai Stress Intensity Factor (SIF) yang digunakan untuk perhitungan umur lelah dengan metode fracture mechanics. Nilai SIF dengan initial crack 10 mm pada end bracket tebal 12 mm sebesar 528,84 MPa√mm, tebal 14 mm sebesar 418,79 MPa√mm, tebal 16 mm sebesar 368,56 MPa√mm. Umur lelah pada setiap variasi tebal end bracket, yaitu tebal 12 mm sebesar 519.206,809 cycles, tebal 14 mm sebesar 784.929,402 cycles, tebal 16 mm sebesar 1.165.922,132 cycles. Umur lelah ini dikonversi ke dalam bentuk hari. Sehingga, diperoleh umur lelah end bracket dengan tebal 12 mm sebesar 631,942 hari, tebal 14 mm sebesar 955,361 hari, tebal 16 mm sebesar 1.419,078 hari.
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Structural failure such as fatigue can lead to cracking in ships. When a structure reaches its fatigue life limit, it will develop an initial crack and eventually fracture. In oil tankers, structural fatigue often occurs in critical areas such as the connection between the inner bottom bracket and the hopper sloping plate (end bracket). In this study, three variations of end bracket thickness were used: 12 mm, 14 mm, and 16 mm. The fatigue life analysis of the ship was conducted using finite element software, where the loading calculations and modeling were based on the Common Structural Rules for Double Hull Oil Tankers (CSR-T). The global model was loaded with sloshing loads from the tank cargo (internal load). The global modeling in the finite element software used three cargo compartments with the end bracket as the local model. From the global model analysis using the finite element method, the maximum normal stress value in the end bracket area was obtained. This stress value from the global analysis was then used for local model analysis. The local model analysis provided the Stress Intensity Factor (SIF) values, which were used for calculating the fatigue life using fracture mechanics. The SIF values with an initial crack of 10 mm were 528,84 MPa√mm for the 12 mm thick end bracket, 418,79 MPa√mm for the 14 mm thick end bracket, and 368,56 MPa√mm for the 16 mm thick end bracket. The fatigue life for each thickness variation was 519.206,809 cycles for the 12 mm thickness, 784.929,402 cycles for the 14 mm thickness, and 1.165.922,132 cycles for the 16 mm thickness. This fatigue life was then converted into days, resulting in a fatigue life of 631,942 days for the 12 mm thickness, 955,361 days for the 14 mm thickness, and 1.419,078 days for the 16 mm thickness.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Loading Room Bracket, Fracture Mechanics, Crack Propagation, Stress Intensity Factor (SIF), Fatigue Life, Bracket Ruang Muat, Fracture Mechanics, Stress Intensity Factor (SIF), Perambatan Retak, Umur Lelah.
Subjects:	V Naval Science > VM Naval architecture. Shipbuilding. Marine engineering > VM156 Naval architecture
Divisions:	Faculty of Marine Technology (MARTECH) > Naval Architecture and Shipbuilding Engineering > 36201-(S1) Undergraduate Thesis
Depositing User:	Fardhan Jaya Putera
Date Deposited:	06 Aug 2024 07:02
Last Modified:	06 Aug 2024 07:02
URI:	http://repository.its.ac.id/id/eprint/112827

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