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1 University of Rostock | Naval Architecture and Ocean Engineering February 2013 University of Rostock | Naval Architecture and Ocean Engineering
Structural Design and Optimization of an Ice Breaking Platform Supply Vessel Juncheng Wang Supervisor: Prof. Patrick Kaeding
2 University of Rostock | Naval Architecture and Ocean Engineering February 2013
► Opportunity
– Territorial waters disputes
– New business route
– Energy treasure
► Challenge
– Multi-year ice load
– Low temperature
– Economical efficiency
• Lighter
• Cheaper
• …
Go northward
3 University of Rostock | Naval Architecture and Ocean Engineering February 2013
Project outline
► Rule-based structural design, polar class
PC2, PC4 and PC6
► Structural optimization considering weight
► Structural optimization taking production into
account
► Weight assessment for proposal design
► Rules Calc approval
► FEM approval
4 University of Rostock | Naval Architecture and Ocean Engineering February 2013
Process for polar class ships design
► Rules
– Ship structures (General)
– General cargo ships
– Offshore supply vessels
– Polar class
► Ice load patch & Ice belt
► Other structure
► Global strength
► Corrosion and material
► Additional:
– Analytical method (buckling)
– Plastic design theory (FEM)
5 University of Rostock | Naval Architecture and Ocean Engineering February 2013
4C Optimization method for panel
4C method
► Criteria
Average thickness, tave
► Constrains Rules + experience
► Connection Stiffeners + Primary elements
► Catalog Rules + Shipyard documents
Advantages
► Practical
► Flexible
► Modularized
► Globally arrival
6 University of Rostock | Naval Architecture and Ocean Engineering February 2013
► Find main parameters
► Define primary variables & constrains
► Analyze the effect of variables
► Select reasonable variable range
► Global bending moment
Optimization process
Plate thickness calculation
Is the total tave the smaller?
Stiffener profile catalog
Output & stop
Longitudinals & transversals check
Import different variables cluster into calculation
Plate check
Stiffener section modulus and moment inertia calculation
Average thickness tave calculation
Primary element profile catalog
Variables clusters catalog
No
Yes
7 University of Rostock | Naval Architecture and Ocean Engineering February 2013
Panel based optimization
► Midbody & Intermediate
► Sort of panels
– Shell
– Deck
– Longitudinal bulkhead
– Transversal bulkhead
► Primary parameters Opt.
► Secondary parameters Opt.
– Plate
– Stiffener
– Bracket
8 University of Rostock | Naval Architecture and Ocean Engineering February 2013
Stiffening method
► Transversal stiffening is more weight effective
– Compressive load
– Shape of ice load patch
200
400
600
05001000150020002500
35
40
45
50
55
60
65
Stiffener spacing (mm)Stringer/Girder spacing (mm)
Panel A
vera
ge t
hic
kness (
mm
)
0
500
1000
100020003000400050006000
30
35
40
45
50
55
Stiffener spacing (mm)Stringer/Girder spacing (mm)
Panel A
vera
ge t
hic
kness (
mm
)
9 University of Rostock | Naval Architecture and Ocean Engineering February 2013
Web frame spacing
Bigger web frame spacing
► Bottom: effective
► Side shell: higher tave and welding complexity
800 1000 1200 1400 1600 1800 2000 2200 240050
55
60
65
70
75
80
Web frame spacing (mm)
Panel A
vera
ge t
hic
kness (
mm
)
SS1
SS5
800 1000 1200 1400 1600 1800 2000 2200 240010
15
20
25
30
35
Web frame spacing (mm)
Web f
ram
e p
late
thic
kness (
mm
)
SS1
SS5
SS7
10 University of Rostock | Naval Architecture and Ocean Engineering February 2013
Stringer spacing
► Bigger spacing is more effective
– Shape of ice load patch
– Geometrical limitation due to GA
500 1000 1500 2000 2500 300050
60
70
80
90
100
110
120
130
140
Stringer spacing (mm)
Panel A
vera
ge t
hic
kness (
mm
)
SS1
SS2
SS3
SS4
SS5
SS7
Ice load patch
PC2: 3.12 * 0.86 m
11 University of Rostock | Naval Architecture and Ocean Engineering February 2013
Stiffener spacing (1/3)
► Panels at shell
– PC2-6: Smaller spacing, smaller tave, bigger peak
pressure
– PC2→6: Milder tendency, lower weight
200 300 400 500 600 700 80045
50
55
60
65
70
75
80
85
90
95
Stiffener spacing (mm)
Panel A
vera
ge t
hic
kness (
mm
)
SS1
SS2
SS3
SS5
SS7
200 400 600 800 1000 1200 1400 160020
25
30
35
40
45
50
55
60
Stiffener spacing (mm)
Panel A
vera
ge t
hic
kness (
mm
)
SS1
SS2
SS3
SS5
SS7
PC2 PC6
12 University of Rostock | Naval Architecture and Ocean Engineering February 2013
200 300 400 500 600 700 80010
15
20
25
30
35
40
Stiffener spacing (mm)
Panel A
vera
ge t
hic
kness (
mm
)
WD2
D2
D6
IB2
Stiffener spacing (2/3)
► Panels at deck
– Compressive load is critical sometimes
– Plate thickness is more sensitive
– Minimum solution various
200 300 400 500 600 700 80010
15
20
25
30
35
40
Stiffener spacing (mm)
Panel A
vera
ge t
hic
kness (
mm
)
WD2
D2
D6
IB2
PC2, deck PC6, deck
13 University of Rostock | Naval Architecture and Ocean Engineering February 2013
Stiffener spacing (3/3)
► Longitudinal bulkhead
– Similar with shell panels
► Transversal bulkhead
– Minimum in the middle
200 300 400 500 600 700 8002
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
X: 433.3
Y: 2.086
X: 433.3
Y: 3.258
Stiffener spacing of transversal bulkhead (mm)
Weig
ht
of
transvers
al bulk
head p
anel (t
)
X: 354.5
Y: 2.683
TB1,2
TB3,4
TB5,6
200 300 400 500 600 700 8008
10
12
14
16
18
20
Stiffener spacing of longitudinal bulkhead (mm)
Panel avera
ge t
hic
kness (
mm
)
LB1
LB2
LB3
14 University of Rostock | Naval Architecture and Ocean Engineering February 2013
Cost optimization
► Factors/Modulus
– Total part number – Each panel
– Total welding length – Each panel
– Other customized parameter
► Criteria
– Pareto Frontier diagram
– Weight of cost (vertical coordinate)& structural
weight (horizontal coordinate)
15 University of Rostock | Naval Architecture and Ocean Engineering February 2013
Cost optimization – Midbody
Part number Welding length
Sh
ell
De
ck
2600 2650 2700 2750 2800 2850 2900 2950 3000 3050 31002
4
6
8
10
12
14x 10
4
Total weight of deck panels (t)
Tota
l part
num
ber
of
deck p
anels
533
400
320
267
228
200
2850 2900 2950 3000 3050 3100 3150 32000.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2x 10
5
Total weight of shell panels (t)
Tota
l part
num
ber
of
shell
panels
533
400
320
267
228
200
2850 2900 2950 3000 3050 3100 3150 32001
1.5
2
2.5
3
3.5x 10
5
Total weight of shell panels (t)
Tota
l w
eld
ing length
of
shell
panels
(m
)
533
400
320
267
228
200
2600 2650 2700 2750 2800 2850 2900 2950 3000 3050 31001
1.5
2
2.5
3
3.5
4x 10
5
Total weight of deck panels (t)
Tota
l w
eld
ing length
of
deck p
anels
(m
)
533
400
320
267
228
200
16 University of Rostock | Naval Architecture and Ocean Engineering February 2013
Cost optimization – Intermediate
200 250 300 350 400 450 500 550 6001
2
3
4
5
6
7x 10
4
Total weight of shell panels (t)
Tota
l w
eld
ing length
of
shell
panels
(m
)
400
320
267
228
200
200 250 300 350 400 450 500 550 6000.5
1
1.5
2
2.5
3
3.5
4
4.5x 10
4
Total weight of shell panels (t)
Tota
l part
num
ber
of
shell
panels
400
320
267
228
200
200 250 300 350 400 450 500 550 6000.5
1
1.5
2
2.5
3x 10
4
Total weight of deck panels (t)
Tota
l part
num
ber
of
deck p
anels
400
320
267
228
200
200 250 300 350 400 450 500 550 6001
2
3
4
5
6
7
8x 10
4
Total weight of deck panels (t)
Tota
l w
eld
ing length
of
deck p
anels
(m
)
400
320
267
228
200
Part number Welding length
Sh
ell
De
ck
17 University of Rostock | Naval Architecture and Ocean Engineering February 2013
9300 9400 9500 9600 9700 9800 9900 10000 10100 102001.5
2
2.5
3
3.5
4
4.5
5
5.5x 10
5
Total weight of main structure at midbody and intermediate (t)
Tota
l part
num
ber
of
main
str
uctu
re a
t m
idbody a
nd inte
rmedia
te
Cost optimization – Midbody+Intermediate
► Overall optimization (>2,800)
– Compressive load is critical
– Best solution could be in the middle
9300 9400 9500 9600 9700 9800 9900 10000 10100 102005
6
7
8
9
10
11x 10
5
Total weight of main structure at midbody and intermediate (t)Tota
l w
eld
ing length
of
main
str
uctu
re a
t m
idbody a
nd inte
rmedia
te (
m)
18 University of Rostock | Naval Architecture and Ocean Engineering February 2013
Design Proving
► Rules Calc
– Partially rules’ check
► FEM
– Plastic hinge theory
– Elastic FEM
– Result transfer
19 University of Rostock | Naval Architecture and Ocean Engineering February 2013
Conclusion
► Transversal structure
► Less stringer
► Bigger web frame spacing
► Global strength is not a problem
► Reduce stiffener spacing
► Cost optimization can be improved
