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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 ?