Analisa Tegangan Sisa Dan Distorsi Pada Sambungan Tubular Tipe T Dengan Pengaruh Post Weld Heat Treatment Menggunakan Metode Elemen Hingga

Pangesti, Anggi Aprilia (2016) Analisa Tegangan Sisa Dan Distorsi Pada Sambungan Tubular Tipe T Dengan Pengaruh Post Weld Heat Treatment Menggunakan Metode Elemen Hingga. Undergraduate thesis, Institut Teknology Sepuluh Nopember.

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Abstract

Komponen struktur lepas pantai yang umumnya sambungan tubular harus diperhatikan proses pengelasannya karena dapat mempengaruhi kekuatan sambungan. Pemanasan lokal pada sambungan tubular dan proses pendinginan yang cepat dapat menyebabkan terjadinya tegangan sisa. Tegangan akibat panas pengelasan ini dapat menyebabkan distorsi pada sambungan tubular. Dalam tugas akhir ini akan dibahas tentang tegangan sisa dan distorsi yang terjadi pada sambungan tubular T akibat pengelasan. Simulasi pengelasan sambungan tubular T dilakukan menggunakan software berbasis metode elemen hingga dengan data parameter pengelasan berdasarkan Welding Procedure Spesification (WPS) dari fabrikator. Sambungan tubular T dimodelkan dengan spesifikasi material baja SM 400. Simulasi terbagi menjadi dua analisa yaitu analisa termal dan analisa struktural. Dalam analisa termal didapatkan suhu pengelasan dari daerah las dan dalam analisa struktural didapatkan tegangan sisa. Distribusi tegangan sisa ditinjau untuk tegangan sisa arah aksial pada bagian atas, tengah, dan bawah chord. Nilai distribusi tegangan sisa arah aksial berkisar antara -70 MPa sampai 244 MPa. Sedangkan nilai total deformasi maksimum yang terjadi setelah pengelasan adalah 3,3 mm. Setelah simulasi pengelasan dilakukan dilanjutkan simulasi post weld heat treatment (PWHT) dengan variasi suhu dan waktu tahan pada sambungan tubular sesuai dengan ketentuan AWS D1.1:2000. Hal ini dilakukan untuk mengurangi tegangan sisa yang terjadi. Simulasi PWHT terbagi menjadi heating rate, holding time, dan cooling time pada analisa termal lalu dilanjutkan analisa struktural. Tegangan sisa hasil PWHT ditinjau pada bagian atas chord untuk melihat pengurangan tegangan sisa. Setelah dilakukan semua variasi suhu dan waktu tahan PWHT, tegangan sisa berkurang. Dari semua variasi PWHT, nilai tegangan sisa arah aksial maksimum bagian atas chord berkurang dari 141 MPa menjadi -14,6 MPa. =========================================================================================================== Components of offshore structures which is generally tubular connection must be considered because the welding process can affect the strength of the connection. Local heating in tubular connections and the rapid cooling process can cause residual stress. The residual stress is calculated based on the strain due to temperature distribution during cooling time, from welding temperature to the room temperature. Stress due to welding temperature causes distortion of the tubular connection. This final project is to carry out simulation of residual stress and distortion analysis of Tubular T-joint caused by welding process. Welding simulation performed with finite element based software. Tubular T-joints modeled with material specifications SM 400, while the data for welding simulation taken from Welding Procedure Spesification (WPS) made by fabricator. Simulation analysis comprises of two steps which are thermal analysis and structural analysis. In thermal analysis we can obtain welding temperature of the weld area, whereas structural analysis we can obtain the residual stress. The distribution of axial residual stress were observed at the top, the middle and the bottom chord. The value of residual stress distribution in axial direction ranges from -70 MPa to 244 MPa. Meanwhile the total value of the maximum deformation that occurs after welding process is 3.3 mm. To reduce residual stress can be done by post-weld heat treatment (PWHT) with temperature and holding time specified in accordance with the thickness and type of material connection. After welding simulation is done PWHT simulation performed with temperature and holding time variations on the tubular connection in accordance with the provisions of AWS D1.1: 2000. PWHT simulation is divided into heating rate, holding time, and cooling time in the thermal analysis and continue with structural analysis. The residual stress results after PWHT is reviewed in the upper chord to see any reduction in residual stress. The maximum stress value of residual stress the upper chord in axial direction is 141 MPa. After all the variations of temperature and holding time PWHT, the residual stress is reduced significantly. Of all the variations of PWHT, the maximum residual stress the upper chord in axial direction reduced from 141 MPa to -14.6 MPa.

Item Type: Thesis (Undergraduate)
Additional Information: RSKe 623.843 Pan a
Uncontrolled Keywords: tegangan sisa, deformasi, sambungan tubular T, metode elemen, hingga, dan post weld heat treatment
Subjects: V Naval Science > VM Naval architecture. Shipbuilding. Marine engineering
Divisions: Faculty of Marine Technology (MARTECH) > Ocean Engineering > 38201-(S1) Undergraduate Thesis
Depositing User: Mr. Tondo Indra Nyata
Date Deposited: 26 Dec 2019 02:04
Last Modified: 26 Dec 2019 02:04
URI: http://repository.its.ac.id/id/eprint/72469

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