Analisis Umur Lelah Poros Baling Baling Kapal Akibat Retak Dan Beban Puntir

Qinthara, Andi Alvyn Shafa (2026) Analisis Umur Lelah Poros Baling Baling Kapal Akibat Retak Dan Beban Puntir. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Poros baling-baling kapal (propeller shaft) merupakan salah satu komponen penting pada sistem penggerak kapal yang berfungsi meneruskan daya dari mesin ke baling-baling. Selama beroperasi, poros ini menerima beban torsi secara terus-menerus yang berpotensi menyebabkan timbulnya retak (crack) akibat kelelahan material (fatigue), sehingga dapat menurunkan kekuatan struktural poros dan berisiko menyebabkan kegagalan. Penelitian ini bertujuan untuk menganalisis pengaruh retak awal berbentuk semi-elips terhadap distribusi tegangan, Stress Intensity Factor (SIF), serta memprediksi umur lelah (fatigue life) pada poros baling-baling kapal berbahan material stainless steel 316L akibat pembebanan puntir (torsi) sebesar 32.000.000 N.mm, dengan variasi orientasi retak melintang dan memanjang yang ditempatkan di bagian tengah poros. Analisis dilakukan menggunakan metode elemen hingga (Finite Element Method) dengan bantuan perangkat lunak Ansys 2024 R2, dan perhitungan laju perambatan retak dilakukan menggunakan pendekatan hukum Paris (Paris' Law) berdasarkan nilai K3 sebagai mode dominan pada kondisi pembebanan torsi. Hasil penelitian menunjukkan bahwa tegangan maksimum pada poros tanpa retak sebesar 54,542 MPa, meningkat menjadi 55,629 MPa pada retak melintang dan 58,804 MPa pada retak memanjang. Nilai Stress Intensity Factor Range (ΔK) juga meningkat seiring bertambahnya kedalaman retak pada kedua orientasi tersebut. Berdasarkan hasil perhitungan umur lelah, diperoleh perkiraan umur pakai poros sebesar 27,51 tahun untuk retak melintang dan 26,25 tahun untuk retak memanjang, yang menunjukkan bahwa orientasi retak memanjang menghasilkan tingkat kekritisan dan risiko kegagalan yang lebih tinggi dibandingkan retak melintang pada poros berbahan material 316L dengan pembebanan puntir sebesar 32.000.000 N.mm.
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The propeller shaft is one of the essential components in a ship's propulsion system, functioning to transmit power from the engine to the propeller. During operation, this shaft continuously experiences torsional loading, which has the potential to initiate cracks due to material fatigue, thereby reducing the structural strength of the shaft and increasing the risk of failure. This study aims to analyze the effect of an initial semi-elliptical crack on stress distribution, Stress Intensity Factor (SIF), and to predict the fatigue life of a ship propeller shaft made of 316L stainless steel subjected to a torsional load of 32,000,000 N.mm, with variations in crack orientation—transverse and longitudinal—positioned at the mid-section of the shaft. The analysis was carried out using the Finite Element Method (FEM) with the aid of Ansys 2024 R2 software, and the crack propagation rate was calculated using the Paris' Law approach based on the K3 value as the dominant mode under torsional loading conditions. The results show that the maximum stress on the shaft without a crack was 54.542 MPa, increasing to 55.629 MPa for the transverse crack and 58.804 MPa for the longitudinal crack. The Stress Intensity Factor Range (ΔK) also increased with increasing crack depth for both orientations. Based on the fatigue life calculations, the estimated service life of the shaft was 27.51 years for the transverse crack and 26.25 years for the longitudinal crack, indicating that the longitudinal crack orientation results in a higher level of criticality and risk of failure compared to the transverse crack, for a shaft made of 316L material under a torsional load of 32,000,000 N.mm.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	poros baling-baling kapal, retak, beban torsi, stainless steel 316L, Stress Intensity Factor, umur lelah, hukum Paris ======================================================================================================================== ship propeller shaft, crack, torsional load, stainless steel 316L, Stress Intensity Factor, fatigue life, Paris' Law
Subjects:	V Naval Science > VM Naval architecture. Shipbuilding. Marine engineering > VM156 Naval architecture V Naval Science > VM Naval architecture. Shipbuilding. Marine engineering > VM753 Propellers
Divisions:	Faculty of Marine Technology (MARTECH) > Naval Architecture and Shipbuilding Engineering > 36201-(S1) Undergraduate Thesis
Depositing User:	Andi Alvyn Shafa Qinthara
Date Deposited:	05 Aug 2026 04:15
Last Modified:	05 Aug 2026 04:15
URI:	http://repository.its.ac.id/id/eprint/143966

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