Download FEM MidShip Project Report PDF

TitleFEM MidShip Project Report
TagsPhysics Mechanical Engineering Physics & Mathematics Building Engineering
File Size4.2 MB
Total Pages21
Document Text Contents
Page 1

Structural Analysis of Midship Section of General Cargo Ship 


NAME # 6098 Term Project  Page 1 











NAME 6098


FINITE ELEMENT METHODS

TERM PROJECT












RAJESH KOPPARTHI

AVINASH KARRI

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Structural Analysis of Midship Section of General Cargo Ship 


NAME # 6098 Term Project  Page 2 


TABLE OF CONTENTS


1. INTRODUCTION.................................................................................................. 3


2. METHODOLOGY ................................................................................................ 5


3. DESIGN REQUIREMENTS................................................................................. 6

3.1 Design Criteria ............................................................................................................................6
3.2 Design Loads................................................................................................................................6
3.3 Materials.......................................................................................................................................6
3.4 Geometrical Properties of the Model...........................................................................................7
3.5 Element Type...............................................................................................................................7
3.6 Finite Element Model...................................................................................................................8
3.7 Boundary Conditions..................................................................................................................10


4. STRENGTH ANALYSIS.....................................................................................12

4.1 Loading Condition # 1..............................................................................................................12
4.2 Loading Condition # 2..............................................................................................................14
4.3 Loading Condition # 3..............................................................................................................15
4.4 Loading Condition # 4…………..............................................................................................16
4.5 Loading Condition # 5..............................................................................................................17
4.6 Loading Condition # 6..............................................................................................................18
4.7 Loading Condition # 7..............................................................................................................19
4.8 Summary of Results…..............................................................................................................19


5. REFERENCES…............................................................................................... 20


6. APPENDIX……….............................................................................................. 21

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Structural Analysis of Midship Section of General Cargo Ship 


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View 3



3.7 Boundary Conditions:

Many designers find the application of boundary conditions quite
daunting but be assured that it is very simple. All you have to do is consider how the
structure will be restrained and constrain the degrees of freedom to make the model
behave in a realistic manner. There are only six degrees of freedom to consider, 3
translation (tx,ty,tz) and three rotation, - the rotation about each axis (rx,ry,rz). One type
of boundary condition to consider is the symmetric boundary condition. If we could
model quarter of our structure and get an accurate result using symmetrical boundary
conditions, we can size quarter of the model and significantly reduce the time to build
and solve it. So for the 9m x 13m x 15 m model, symmetrical boundary conditions are
given in X and Z directions so that it represents the full Compartment of 18 m x26m x
15m size.

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Structural Analysis of Midship Section of General Cargo Ship 


NAME # 6098 Term Project  Page 11 


As there will be a Transverse Bulkhead at the end of the compartment, the
model is fixed at the end in Longitudinal Direction. A transverse floor is considered at
the mid of the compartment. So the double bottom is restrained in vertical (Y) direction at
the mid of the Compartment (at end of the Model in Long direction towards symmetrical
side). Pillars (Three in Long and Two in Tran directions which makes total of 5) are
considered to support the loading on Decks and Stiffeners. As Pillars are not modelled as
structure, it is taken as boundary condition which restrains the portion, where pillar
connects the deck, in vertical direction. Also, the model is restrained in the Longitudinal
direction (Z – axis).





Model with Loads and Boundary Conditions

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Structural Analysis of Midship Section of General Cargo Ship 


NAME # 6098 Term Project  Page 20 



5. REFERENCES




1. NAME # 6098 Lecture Handouts by Dr. Pingsha Dong

2. ABS Rules for Steel Vessels 2006

3. AISC – Allowable Stress Design, 9th Edition

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NAME # 6098 Term Project  Page 21 





6. APPENDIX

ABS REGULATIONS FOR MINIMUM THICKNESS:

We examined ABS Rules for Building and Classing Steel Vessel 2007 to find
requirements that would apply to the bottom, side shell and deck plating, stiffeners design
for the vessel. We made the assumption that our designed plate will have thickness
greater than the minimum requirements of the specified ABS requirements below.
An additional requirement is a 15:1 (approximately) ratio for the stiffener length to
width/depth dimensions. This requirement was made based on the application of the
stiffened plate. In this problem we are considering the length to depth as 11
(approximately)

3.9 Side Shell Plating
The minimum thickness, t, of the side shell plating throughout the amidship 0.4L,
for vessels having lengths not exceeding 427 m (1400 ft), is to be obtained from the
following equation:
t = ( s/645 ) (L 15.2)(d / Ds ) + 2.5 mm for L 305 m
where,
s = spacing of transverse frames or longitudinals, in mm
L = length of vessel, as defined in 3-1-1/3.1, in m
d = molded draft, as defined in 3-1-1/9, in m
Ds = molded depth, in m

3.13.2 Bottom Shell Plating
The thickness, t, of the bottom plating amidships is not to be less than obtained from the
following equations or the thickness determined by 3-2-2/3.17, whichever is greater.

3.13.2(a) For Vessels with Transversely-framed Bottoms
t = ( s/519 ) L 19.8)(d / Ds ) + 2.5 mm for L 183 m

3.13.2(b) For Vessels with Longitudinally-framed Bottoms
t = ( s/671 ) (L 18.3)(d / Ds ) + 2.5 mm for L 122 m

Strength Deck Outside Line of Openings
With Transverse Beams 1a and 1b (note 1)
t = 0.01sb + 2.3 mm for sb 760 mm
t = 0.0066sb + 4.9 mm for sb > 760 mm
Reference: ABS Rules for Steel Vessels 3-2-2 3.12 Page 69

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