ANALISIS INTERNAL CRACK AKIBAT ROLLING CONTACT FATIGUE (RCF) TERHADAP AS RODA TIPE CC-1 PADA KERETA API PENUMPANG

FAJAR NUGROHO, . (2026) ANALISIS INTERNAL CRACK AKIBAT ROLLING CONTACT FATIGUE (RCF) TERHADAP AS RODA TIPE CC-1 PADA KERETA API PENUMPANG. Sarjana thesis, UNIVERSITAS NEGERI JAKARTA.

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Abstract

As roda kereta api merupakan komponen vital yang rentan mengalami Rolling Contact Fatigue (RCF) akibat beban siklik berulang dan kontak roda-rel, yang berpotensi memicu terjadinya internal crack (retak bagian dalam) berbahaya yang tidak terlihat secara visual dari luar. Penelitian ini bertujuan untuk menganalisis karakteristik dan lokasi terjadinya internal crack pada as roda tipe CC-1 kereta api penumpang, mengidentifikasi pengaruh RCF serta faktor dominan penyebab retakan, dan mengevaluasi tingkat keandalan (reliability) hasil inspeksi Ultrasonic Testing (UT). Penelitian kuantitatif ini dilaksanakan melalui observasi langsung di UPT Balai Yasa Manggarai dan pengujian UT. Data hasil pengujian diolah menggunakan pemodelan Finite Element Analysis (FEA) dan Hertzian Contact Stress, dievaluasi menggunakan pendekatan Fracture Mechanics, dianalisis akar penyebabnya melalui Diagram Fishbone, serta dihitung tingkat keandalannya menggunakan metode Distribusi Weibull. Hasil analisis menunjukkan bahwa internal crack mayoritas terkonsentrasi pada area wheel seat dan journal dengan tingkat keparahan retak antara 11% hingga 89%. Simulasi FEA membuktikan area tersebut menerima konsentrasi tegangan geser maksimum dan getaran ekstrem yang memicu inisiasi retak, diperparah oleh beban lentur berulang dan korosi gesek (fretting). Evaluasi Fracture Mechanics mengonfirmasi bahwa kedalaman retak yang melebihi batas toleransi kritis (>20%, atau sekitar 37%) menyebabkan penurunan kekuatan struktur secara drastis sehingga as roda wajib diafkir. Berdasarkan analisis Distribusi Weibull, komponen mengalami indikasi kegagalan dini (early-life failure, β<1) dengan estimasi umur pakai aman (Mean Time To Failure/MTTF) mencapai 4.732,1 jam operasional. *********** Railway axles are critical structural components highly susceptible to Rolling Contact Fatigue (RCF) due to cyclic loading and repeated wheel-rail contact, which can trigger dangerous internal cracks that cannot be visually detected from the outside. This study aims to analyze the characteristics and locations of internal cracks in type CC-1 passenger railway axles, evaluate the impact of RCF and dominant root causes, and assess the reliability level of Ultrasonic Testing (UT) inspection results. This quantitative research was conducted through direct observation at UPT Balai Yasa Manggarai and UT inspections. Test data were processed using Finite Element Analysis (FEA) and Hertzian Contact Stress modeling, evaluated via Fracture Mechanics, analyzed for root causes using a Fishbone Diagram, and calculated for reliability using the 2-parameter Weibull Distribution method. The results revealed that internal cracks primarily occurred in the wheel seat and journal regions, with crack severity levels ranging between 11% and 89%. FEA simulations confirmed that these areas experience maximum shear stress concentration and extreme vibration, which accelerate crack initiation when combined with cyclic bending loads and fretting corrosion. Fracture Mechanics evaluation demonstrated that crack depth exceeding the critical tolerance limit (>20%, around 37%) severely impairs structural integrity, necessitating immediate axle rejection. Based on Weibull Distribution analysis, the component exhibits early-life failure characteristics (β<1) with an estimated safe service life (Mean Time To Failure/MTTF) of 4,732.1 operational hours.

Item Type:	Thesis (Sarjana)
Additional Information:	1). Dr. Siska Titik Dwiyati, M.T. ; 2). Dr. Dyah Arum Wulandari, M.T.
Subjects:	Ilmu Sosial > Transportasi Sains > Matematika Sains > Statistika Teknologi dan Ilmu Terapan > Teknik Jalan Kereta Api Teknologi dan Ilmu Terapan > Teknik Mesin, Mekanika Teknik Teknologi dan Ilmu Terapan > Manufaktur
Divisions:	FT > D IV Teknologi Rekayasa Manufaktur
Depositing User:	Fajar Nugroho .
Date Deposited:	13 Aug 2026 08:06
Last Modified:	13 Aug 2026 08:06
URI:	http://repository.unj.ac.id/id/eprint/69976

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