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.
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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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