Ahmad, Mahasin Maulana (2015) Studi Pengaruh Slamming Terhadap Kekuatan Struktur Global Dan Lokal Drillship Padab Kondisi Transit. Masters thesis, Institut Teknologi Sepuluh Nopember.
Preview |
Text
4113201001-Master Thesis.pdf - Published Version Download (5MB) | Preview |
Abstract
Slamming merupakan fenomena yang terjadi pada bangunan apung. Drillship
sebagai bangunan apung, mengalami slamming pada saat bagian haluan kapal
naik melewati permukaan gelombang dan masuk kembali ke dalam air dengan
kecepatan relatif vertikal haluan yang melewati kecepatan ambang batas
slamming. Besarnya beban gelombang yang terjadi pada saat drillship transit dari
satu titik ke titik yang lain mengakibatkan beban dinamis (quasi statis) yang
berpengaruh terhadap respon dan kekuatan struktur. Dalam studi ini dilakukan
analisis slamming terhadap drillship 35000 ton dengan variasi kecepatan 7 knot,
12 knot, 13 knot dan 14 knot. Langkah pertama yang dilakukan adalah dengan
meninjau gerakan kopel heave dan pitch yang terjadi pada bagian haluan drillship.
Gerakan kopel heave dan pitch dikorelasikan dengan sudut fase yang sesuai akan
menghasilkan gerak relatif vertikal haluan. Perhitungan RAO gerakan heave dan
pitch diperoleh dengan menggunakan software hydrostar. Hasil analisis
hydrostar, menunjukkan bahwa RAO maksimal gerakan relatif vertikal haluan
terjadi pada saat drillship transit dengan kecepatan 14 knot pada frekuensi rendah
0.187 rad/s sebesar 4.3233 m/m. Hasil perhitungan RAO dikorelasikan dengan
spektra gelombang untuk mengetahui respon spektra dan didapatkan karakteristik
slamming yang terjadi pada drillship seiring dengan kenaikan tinggi gelombang
signifikan. Karakteristik slamming maksimal terjadi pada Hs 15 m, peluang
terjadinya slamming 0.483 kali, intensitas slamming 124.451 kali/jam dan tekanan
slamming 492.232 kPa. Hasil perhitungan tekanan slamming di konversikan
kedalam bentuk gaya dengan mengintegralkan terhadap luasan yang ditinjau.
Karakteristik respon struktur dinamis (quasi statis) yang berupa shear force dan
bending moment digunakan sebagai beban yang diberikan pada drillship dalam
Metode Elemen Hingga. Analisis global drillship, terjadi ultimate pada Hs 11 m
yakni stress sebesar 451 MPa untuk jenis material logam ASTM A852 (430 MPa).
Sedangkan analisis lokal, dilakukan dengan menambahkan gaya yang terjadi
akibat tekanan slamming didaerah haluan, sehingga terjadi ultimate pada Hs
sekitar 11 m yakni stress sebesar 716 MPa untuk jenis material ASTM A852 (430
MPa).
===============================================================================================
Slamming is a phenomenon that occurs on a floating structure. Drillship as a
floating structur occurs a slamming when bow section move to above the wave
elevation and then move down back into the water with the relative speed of the
vertical direction that passed the threshold velocity. The magnitude of the wave
loads that occur during the drillship in transit condition from one point to another
point lead dynamic loads (quasi-static) which will effect on the strength and
response structures. In this study, the analysis of slamming performed on the
drillship that has displacement of 35000 tons with some variations in speed.
Speed variations that will be analyzed are 7 knots, 12 knots, 13 knots and 14
knots. The first step in this analysis is to review the heave and pitch couple motion
that occurs in the bow of the drillship. The couple motion of heave and pitch
correlated with phase angle will produce relative vertical motion on bow.
Software hydrostar is used to obtain the heave and pitch motions RAO. Simulating
on a speed of 14 knots, vertical motion RAO at the bow of drillship reach the
highest point 4.3233 m/m at low frequencies 0.187 rad/sec. RAO calculation
results, correlated with the wave spectrum to determine the response spectra and
obtainted characteristic of slamming that occurs on the drillship along with an
increasing of significant wave height. Maximum slamming characteristics occurs
in significant wave height of 15 m with a probability of slamming by 0.483 times,
slamming intensity by 124.451 times/hour and slamming pressure by 492.232
kPa. The result of slamming pressure is converted be a force through a integral
process of that pressure to its area. Dynamic structural response characteristics
(quasi static) in the form of shear force and bending moment is used as a load
given to the drillship in the Finite Element Method. The collapse occured on the
significant wave height (Hs) of about 11 m amounted 451 Mpa of stress to the
type of metal material ASTM A852 for global analysis. While local analysis is
done by adding the force caused by the pressure of slamming of the bow area and
also collapse on the significant wave height (Hs) of about 11 m is amounted 716
MPa to the type of metal material ASTM A852.
| Item Type: | Thesis (Masters) |
|---|---|
| Additional Information: | RTKe 623.812 8 Ahm s |
| Uncontrolled Keywords: | Drillship, Slamming, quasi-stati, Finite Element Method, Ultimate Strength |
| Subjects: | V Naval Science > VM Naval architecture. Shipbuilding. Marine engineering |
| Divisions: | Faculty of Marine Technology (MARTECH) > Marine Engineering > 36101-(S2) Master Theses |
| Depositing User: | Mr. Tondo Indra Nyata |
| Date Deposited: | 03 Jul 2017 04:28 |
| Last Modified: | 24 Aug 2018 01:52 |
| URI: | http://repository.its.ac.id/id/eprint/41841 |
Actions (login required)
 |
View Item |