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STRUCTURAL DESIGN OF MEGA LNG CARRIER
byHASAN DEEB
EMSHIP Erasmus Mundus Master Course
in Integrated Advanced Ship Design
Szczecin universityPoland, 2013
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SUMMERY
1 Introduction2 LNG ( definition, & market)3 Principle of ship design
4 Main characteristics5 3D model using Poseidon software6 Basic forces acting on ship7 Scantling according to GL rules8 Numerical calculation (FEM)9 Conclusion
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LNG Terminal winoujciu strategic location and advantages
INTRODUCTION
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WHAT ISLNG ?
WHY LNG ?
SIZE OF THEMAKET?
LNG
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Definition Of Problem & Scope Of Work
1- Increasing of demand on LNG sourcesrequire building bigger and biggerships, this make the engineers inchallenge to ensure the safety of shipsand ability to survive carrying thishuge amount of cargo.
2- Design LNG ship which can navigate
under real conditions safely andnumerical verification before build itin shipyard.
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Principle Of Ship Design
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Hull Forms & Type Of LNG Ships
Type A Type B
membran eType C
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Main Characteristics
L oa 293 m
B 49 m
T 12 m
D 27 m
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3D Model In Poseidon
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3D Model In Poseidon
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Basic Forces Acting On Ship
Weight of structure of the ship Weight of cargo buoyancy
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Scantling
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Scantling
= M / W M = bending moment W = section modulus In the longitudinal girders at deck and bottom,
the combined stress resulting is not to exceed230 N/mm 2.
From results maximum values is in Fr 86 :
221 Mpa in deck and 156 Mpa in bottomLoad case 1: load caused by vertical bending and static torsional moment;Load case 2: load caused by vertical and horizontal bending moment as
well as static torsional moment;Load case3: load caused by vertical and horizontal bending moment as
well as static and wave induced torsional moment.
Section modulus values achieved according to results of scantling is W= 55.253 m.
Value of midship section moment of inertia I = 454 m4
.
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Scantling
Results of normal stress distribution
Maximum value in
Load case 1: load caused by vertical bending and static torsional moment
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Scantling
Shear stress distribution
maximum value in load case 3
Von Mises stress distribution
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Estimation Of Mass
Very important task (good results of this work will have big influence on thesuccess of the project )
Give an idea about the coast Move in the right direction for optimization
Longitudinal plate
Longitudinal stiffener
Transversal plates
Transversal stiffenerand girders
Total section weight
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Numerical Calculation
Generate FE model
1- Mesh tolerances
2- boundary conditions
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Generate FE model
3- Loads specifications
3-1 External loads ( draft Marge, wave definitions )
3-2 Internal loads
Numerical Calculation
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Generate FE model
4- Selected load cases4-1 load case 1
Numerical Calculation
Loading condition 2 full tanks with emptytank in middle
External pressure Hydrostatic due to static
water line
Cargo pressure Cargo pressure due to
gravity
Additional applied Rule hogging vertical design
wave bending moment
distribution and permissible
hogging still water bending
moment envelope, M sw, are
to be applied.
External pressure Local wave crest (to be
applied
to full length of FE model)
Studied part, load case 1
97.397.30%97.3
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Generate FE model
4- Selected load cases4-1 load case 2
Numerical Calculation
Loading condition one full tank with two
empty tanks in both sidesExternal pressure Hydrostatic due to static
water line
Cargo pressure Cargo pressure due to
gravity
Additional applied Rule sagging vertical
design wave bending
moment distribution and
permissible sagging still
water bending moment
envelope, M sw, are to be
applied.
External pressure Local wave crest (to be
applied
to full length of FE model)
970%97%0%
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Generate FE model
Adjustment of global bending moment
Numerical Calculation
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Results
1- Distribution of the Von Mises stress stresses1-1 load case 1
Numerical Calculation
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Results
1- Distribution of the Von Mises stress stresses1-1 load case 2
Numerical Calculation
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Model deformations under selected load cases
1- LC1Maximum deflection
In Z = 0.14613
2- LC2
Maximum deflectionIn Z = -0.14082
Numerical Calculation
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Conclusion and comment
The resulted structural scantling from the first approach was verified using thesecond approach which is based on the direct calculation and carried out by performing the finite element analysis of one cargo hold located at the middleof the ship.
The objective of the ship hull structural design is achieving such hull structurecapable of sustaining the different kind of loads which the ship mayencounters during her life, and to serve its intended purpose.
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Thanks you
dzikuje
Lets all hope peace for Syria and all the world
Questions ?