SIDANG TUGAS AKHIR Click to edit Master title style

(1)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

SIDANG TUGAS AKHIR

ANALISIS PERILAKU KEPECAHAN CRANE PEDESTALFPSO BELANAK

Supervisors :

1. Dr. Ir. Rudy Walujo P. MT

2. Prof. Dr. Ir. Eko Budi Djatmiko, M.Sc

By. Aditya Rohmani

(2)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

LATAR BELAKANG

• Kerusakan pada bangunan laut mayoritas diakibatkan oleh kelelahan (fatigue) pada struktur, baik itu pada komponen struktur utama maupun struktur sekunder (Djatmiko, 2003a)

• jika suatu struktur telah melewati batas dari kelelehannya maka akan terjadi sebuah keretakan (crack) yang nantinya dapat menyebabkan adanya kegagalan (failure) pada struktur

• Crane pedestal adalah struktur crane yang paling rentan terhadap kepecahan.hal ini dikarenakan, crane pedestal merupakan tumpuan struktur diatasnya, serta tersambung dengan hull FPSO

Penda- huluan

Meto- dologi

Analisis Global

Analisis Lokal

(3)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

RUMUSAN MASALAH

1. Berapa dan dimana letak tegangan tertinggi (hotspot stress) yang diterima struktur crane pedestal?

2. Berapa nilai stress intensity factor dari crane pedestal akibat adanya retak awal yang terjadi ?

3. Bagaimana crack propagation berdasar pengaruh retak awal pada crane pedestal ? 4. Berapa umur crane pedestal sampai

mengalami fracture failure ?

Kesim- pulan

(4)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

TUJUAN

1. Mendapatkan nilai dan letak tegangan tertinggi (hotspot stress) yang diterima struktur crane pedestal

2. Mendapatkan nilai stress intensity factor dari crane pedestal akibat adanya retak awal yang terjadi.

3. Memperoleh indikasi crack propagation sehubungan dengan bentuk retak awalnya.

4. Mendapatkan umur crane pedestal sampai mengalami fracture failure

(5)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

MANFAAT

1. Identifikasi terhadap beban-beban yang mempengaruhi umur crane pedestal pada FPSO sampai mengalami fracture failure.

2. Dapat mengetahui besarnya pengaruh beban siklis dan beban operasional crane terhadap umur crane pedestal pada FPSO sampai

mengalami fracture failure.

3. Prosedur dan hasil perhitungan dapat dijadikan dasar dalam merancang crane

pedestal dengan pertimbangan beban-beban yang berpengaruh.

(6)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

BATASAN MASALAH

1. Crane pedestal yang ditinjau dalam tugas akhir ini adalah crane pedestal pada FPSO Belanak.

2. Beban-beban yang ditinjau adalah beban gelombang, beban angin, dan beban operasi crane.

3. Analisis fracture mechanics dilakukan pada bagian sambungan crane pedestal dengan hull FPSO.

4. Beban operasi crane diasumsikan statis pada beban maksimal dan tidak mengalami gerakan pada saat FPSO beroperasi.

(7)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

BATASAN MASALAH

5. Pemodelan lokal dilakukan sebatas pada bagian sambungan crane pedestal dengan hull FPSO.

6. Pemodelan struktur lokal menggunakan software ANSYS 11.

7. Nilai defleksi dari crane boom dan pedestal diabaikan.

8. Gerakan yang terjadi dari crane dan boom pada saat operasi diabaikan dan hanya ditinjau beban yang diangkat oleh crane saja.

(8)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

METODOLOGI PENELITIAN

Start

Study Literatur Pedestal CraneFPSO

Fracture

Pengumpulan Data

Pemodelan FPSO (Sofware Maxsurf)

Perhitungan Beban Angin

Opersi

Data Gelombang

Pemodelan FPSO (Sofware Moses) dan

Running Data FPSO

(Dimensi Crane,Hull,

Material Properties AnginData

Operasi Dimensi Crack

Kedalaman Crack Panjang Crack

Perhitungan Transformasi Analisis

Global Gelombang ke Pedestal Crane

(9)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

METODOLOGI PENELITIAN

Pemodelan Lokal Pedestal Crane

dan Hull

Pemodelan Crack

Finish A B

Running ANSYS

Tegangan Maksimum dan

Minimum

Crack Propagation

Umur Kepecahan Mesh

Sensitivity Analysis σ konstan

Ya

Tidak

(10)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

PENGUMPULAN DATA

1. LOA 285 m

2. Depth 26 m

3. Beam 58 m

4. Vessel Draft Full 16.2 m 5. Vessel Draft Medium 14.6 m

6. Vessel Draft Light ^{13.9 m}

7. Displacement 255,000 ton

8. Service Life 30 years

DATA FPSO Penda-

huluan

(11)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

PENGUMPULAN DATA

DATA ANGIN

Deskripsi Gelombang

H_s ( m) T_p (s)

1tahunan 2.9 9.1

10tahunan 4.1 10.3

100tahunan 5.3 11.1

DATA PERIODE ULANG Penda-

huluan

(12)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

MODELING

MAXURF Penda-

huluan

(13)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

MODELING MOSES

(14)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

MOTION FPSO

Derajad Kebebasan

Percepatan

Conoco Phillips Wahyudi Perhitungan

Max. Surge Acc 0.656 m/s² 0.318 m/s² 0.171 m/s²

Max. Sway Acc 2.180 m/s² 1.636 m/s² 1.033 m/s²

Max. Heave Acc 1.054 m/s² 1.405 m/s² 2.445 m/s²

Roll Acc 3.023 rad/s² 3.203 rad/s² 2.001 rad/s²

Pitch Acc 0.679 rad/s² 0.744 rad/s² 0.715 rad/s²

Yaw Acc 0.193 rad/s² 0.249 rad/s² 0.242 rad/s²

(15)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

TRANFORMASI ANALISIS GLOBAL KE CRANE PEDESTAL

Degree of Freedom Acceleration Inertia Force

(m/s²) kN

Max. Surge Acc 0.171 42.921

Max. Sway Acc 1.033 259.283

Max. Heave Acc 2.445 3076.005

Degree of Freedom Acceleration Moment Inertia Moment of Force (rad/s²) mt. m² kN.m.rad

Roll 2.001 377612.27 755602.2

Pitch 0.715 694905.72 496857.6

Yaw 0.242 777411.36 188133.5

(16)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

BEBAN ANGIN



sin S

q C

F

_w

  

9.6 16.4 24.4

0 0.00 0.00 0.00

3 16.09 11.00 15.36

6 64.34 44.01 61.43

9 144.77 99.02 138.22

12 257.37 176.04 245.72

15 402.15 275.06 383.94

velocity Moment at elevation (KN.m) Height

26.6 33.4 41.4

0 0.00 0.00 0.00

3 1.68 0.67 0.63

6 6.70 2.68 2.52

9 15.08 6.04 5.66

12 26.81 10.73 10.07

15 41.89 16.77 15.74

18 60.32 24.15 22.66

velocity Wind Force on elevation y (KN) Height

(17)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

BEBAN OPERASI

Load W

(T) (KN)

5 49.1

10 98.1

20 196.2

30 294.3

40 392.4

50 490.5

(18)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

MODELLING ANSYS

(19)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

MESH SENSITIVITY ANALYSIS

(20)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

MESH SENSITIVITY ANALYSIS

(21)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

FRACTURE MECHANICS METHOD

(22)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

INITIAL CRACK

• Hotspot Stress

Terletak di koordinat (0, 0, 1.5)

• DNV-OS-F201

Dengan dimensi

Panjang : 5

Lebar : 1

Kedalaman : 0.1

(23)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

PERSAMAAN SIF (K)

(24)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

SIF CRACK AWAL

Arah Ketebalan (Thickness)

σ K

x y z sint seqv

Max 2.26E+08 5.44E+07 1.38E+07 2.13E+08 1.96E+08 1.01E+02 Min 1.21E+08 2.91E+07 7.37E+06 1.14E+08 1.05E+08 5.39E+01

Circumferencial

Max 2.26E+08 5.44E+07 1.38E+07 2.13E+08 1.96E+08 1.71E+02 Min 1.21E+08 2.91E+07 7.37E+06 1.14E+08 1.05E+08 9.15E+01

(25)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

PERAMBATAN RETAK

• 0.1mm, 5mm, 10mm, 21mm (0.7 T)

m

C E dN

da

K K K K











  

 ( _max² 2 _max _min _min²)



^



_

nf

ni

af

ai

K m

C dN da

) (

af

ai m xa N C

K

^^









 

) (

1

dN N a  da *

(26)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

PERAMBATAN RETAK

Ks Maks Ks Min da/dN retak circum Siklus

(MPa√mm) (MPa√mm) (mm/cycle) (mm) N

A2 3.96E+02 9.99E+01 5.04E-07 7.91E+03 1.57E+10 A3 4.60E+02 2.46E+02 7.03E-08 8.06E+03 2.20E+09 A4 8.09E+02 4.33E+02 2.08E-06 8.12E+03 2.70E+07

Kt Maks Kt Min da/dN retak tickness Siklus

(MPa√mm) (MPa√mm) (mm/cycle) (mm) N

A2 1.86E+02 9.99E+01 3.12E-10 5.00E+00 1.57E+10 A3 2.60E+02 1.39E+02 2.28E-09 1.00E+01 2.20E+09 A4 6.07E+02 3.25E+02 3.70E-07 2.10E+01 2.70E+07 Retak

Circumferrencial

Retak Thickness

(27)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

UMUR CRACK

Crack panjang retak kedalaman retak umur

(mm) (mm) (tahun)

A1 5.00 0.10 -

A2 7906.66 5.00 62.96

A3 8061.02 10.00 71.77

A4 8117.22 21.00 71.88

(28)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

KESIMPULAN

• Tegangan terbesar(hotspot stress) 68.312MPa

pada koordinat ANSYS (0, 0, 1.5)

• SIF dari crane pedestal akibat adanya retak awal

Ks Max =170.70947 Mpa√mm Ks Min = 91.49545 Mpa√mm Kt Max = 100.6399 Mpa√mm Kt Min = 53.94013 Mpa√mm

(29)

Click to edit Master title style

• Click to edit Master text styles

– Second level

• Third level

– Fourth level

» Fifth level

KESIMPULAN

• Perambatan crack (da/dn)

da/dN Circum = 2.08x10^-6mm/cycle Panjang Circum = 8117.22 mm

da/dN Tickn = 3.70x10^-7mm/cycle Ketebalan = 21 mm

• Crane pedestal

Menembus ketebalan 21mm (0.7t) dan melewati 8117.22 mm membutuhkan waktu 71.88 tahun adalah sama dengan atau 2.936 kali umur

operasi sesuai rancangannya

(30)

DAFTAR PUSTAKA

• Almar-Naess, A.Ed. 1985. FATIGUE HANDBOOK: Offshore Steel Structure. Norway: Tapir Publisher.

• API Specification 2C 5^thEdition. 1995. “Specification for Offshore Cranes”, USA.

• Barltrop, N. dan Okan, B. 2000. FPSO Bow Damage in steep waves. Rogue waves 2000 workshop. Brest.

• Barsom, John M & Rolfe,Stanley T. 1987. Fracture and Fatigue Control in Structures.

Application of Fracture Mechanics. New Jersey.

• Battacharyya, R. 1978. Dynamic of Marine Vehicles. John Wiley and Sons Inc. New York.

• Broek, David. 1987. Elementary Engineering Fracture Mechanics. Netherlands:

Martinus Nijhoff Publishers.

• Chakrabarti, S.K. 2005. Handbook of Offshore Engineering Volume I. Offshore Structure Analysis Inc. Planfield. Illinois. USA

• Djatmiko, E. B. 2003. Fatigue Analysis. Kursus Singkat Offshore Structure Design And Modelling. Surabaya.

• DnV Recommended Practice C205. 2007. Environtmental Loads and Environmental Condition. Norway.

• DnV Recommended Practice OS-F201. 2001. Dynamics Risers. Norway.

• Hakim, Hadi Luqman. 2007. Analisa Perilaku Dinamis FPSO dengan Sistem Internal Turret Mooring. Jurusan Teknik Kelautan ITS, Surabaya

• http://commons.wikimedia.org

• http://www.accutektesting.com

• http://www.quipbase.com

(31)

• http://www. scribd.com

• http://www.wikipedia.com

• Indiyono, P. 2003. Hidrodinamika Bangunan Lepas Pantai. Surabaya : Penerbit SIC.

• Langen, I., dan Than, T. K. 2003. Simulation of Dynamic Behaviour of a FPSO Crane. Stavanger University College. Stavanger.

• McDermott, J. 2004. Belanak Natuna FPSO Technical Data. Jray McDermott.

Indonesia

• Perez, Nestor.2004. Elementary Engineering Fracture Mechanics. Boston:

Kluwer Academic Publishers.

• Peurifoy, R. L. 1996. Construction Planning, Equipment, and Methods 5^thEdition. The McGraw-Hill Companies. New York.

• Philips, Conoco. 2002. Belanak Special Structures Crane Pedestal Frame 42 Elevation. Conoco Indonesia Inc. Ltd., Indonesia.

• Soedjono, J.J. 1989. Diktat Kuliah Perencanaan Sistem Bangunan Laut 1.

Jurusan Teknik Kelautan, ITS. Surabaya.

• Wahyudi, Y.A.N. 2009. Analisis Fatigue dengan Spectral Analysis pada Crane Pedestal Floating Production Storage and Offloading (FPSO) Belanak.

Jurusan Teknik Kelautan ITS. Surabaya

• Wang, C.H. 1996. Introduction to Fracture Mechanics. DSTO Aeronautical and Maritime Research Laboratory, Melbourne

• Wang, C.H. 1996. Introduction to Fracture Mechanics. DSTO Aeronautical and Maritime Research Laboratory, Melbourne.

Moto- dologi

DAFTAR PUSTAKA

(32)