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GCRC-SOP 2nd Year International Workshop
Project 2-1
Stage 1• Fatigue and Fracture design DB
• Hydroforming of deep sea valves
• HISC welding technologies
• Numerical damage models for
materials
• Friction resistance reduction by
polymer
• 2-1: Reliability and Strength Assessment• 2-3: Welding Tech. for High Strength Mat. • 2-5: Chemical Materials for Drag. Red.
Stage 2• Fatigue and fracture assessment
• Drillship/Rig material manufacturing
• Dissimilar weld joints for offshore
Top-side
• UMAT for material nonlinear
simulation
• Polymer control technology
Stage 3• Optimal design for ships and
offshore plants
• Modular design for core parts
• HISC evaluation for weld joints
• Numerical Testing Bed
• Polymer processing technology
• 2-2: Subsea System Modulization• 2-4: Materials for Extreme Environment
Class NK/University of New Orleans
• 잔류응력 및 용접변형 관리기술
• 노후 구조물 안전성 평가 및 유지보수 기술• 극저온 재료 피로파괴성능평가 기술
Class NK/University of New Orleans
• 잔류응력 및 용접변형 관리기술
• 노후 구조물 안전성 평가 및 유지보수 기술• 극저온 재료 피로파괴성능평가 기술
참여 기업(현대/DSME/삼성/STX/비엔스틸라)
• 핵심기술 공동개발 및 기술인력 양성• 핵심 부품소재 설계 및 가공기술 사업화• 부품소재 신뢰성 및 강도 DB 공동활용
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Group 2: Parts and Materials Tech.
Project No. 2-1: Reliability and strength assessment of core parts and material system 2
Demand for offshore structure continues to increase in recent years due to the depletion of shallow water resource and environmental issues Development of core design technology in offshore structural system
is needed
Offshore structures operate under deepwater or extreme environment (low temperature, heavy wave) Systematic reliability assessment technology is required to prevent
fatigue and brittle fracture
※ INTSOK Annual Market Report(2010)
Project No. 2-1: Reliability and strength assessment of core parts and material system 3
Fatal accident due to the fatigue fracture in offshore structures
Alexander kielland
• Data : March, 1980
• Location : Ekofisk field, North sea
• Fatalities : 123 persons
Ocean Ranger
• Data : February, 1982
• Location : Hibernia field, North atlantic
• Fatalities : 84 persons
Mandatory fracture toughness assessment for weld zone and HAZ based on standard code [BS 7448, ASTM E1820]
<Alexander L, Kielland, 1980>
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Reliability and strength assessment of core parts and material system Acquisition of fatigue and fracture assessment DB (2011.09 ~ 2014.02)
• Fatigue strength assessment for low temperature materials
• Investigate for fracture characteristics in offshore structural steels
Development for fatigue fracture analysis method and prediction technology (2014.03 ~ 2017.02)
• Development of advanced fatigue life prediction method
• Development for residual stress/welding distortion control technology
Application of advanced design assessment method for offshore structures (2017.03 ~ 2021.02)
• Development of structural integrity assessment method
• To examine application for large welded structures
Project No. 2-1: Reliability and strength assessment of core parts and material system
• Assessment for fracture toughness in offshorestructural steels
• Investigation of fracture characteristics forHAZ/weld metal at low temperature
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The second year (2011.9 -2013.2)
Project No. 2-1: Reliability and strength assessment of core parts and material system
• Fatigue assessment for various weldedjoints in LNGC
• Development of advanced fatigueanalysis method
• Acquisition of Design curve for LNG cargo tankusing FEA
Fatigue assessment for low temperature
steel in LNGC
Investigation for fracture characteristics
in offshore structural steels
Acquisition of fatigue and
fracture assessment DB
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Fatigue assessment for low temperature materials in LNGC Fatigue test for low temperature materials (SUS304L, INVAR)
Fatigue strength assessment for various weld joints in LNGC
Acquisition of design curve for welded joints in LNG cargo tank using FEA
Investigation for fracture characteristics in offshore structural steels Fracture toughness assessment for offshore structural steel
Assessment of fracture characteristics for base metal, HAZ and weld metal
Assessment of 7% nickel steel in LNG cargo tanks Fatigue test, fracture toughness assessment and FCGR for 7% nickel steel
Development of fatigue design methodology for independent tank
Assessment of fracture toughness and fatigue strength at cryogenic temperature
Project No. 2-1: Reliability and strength assessment of core parts and material system
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Fatigue assessment of heavy plates considering thickness effect Development of fatigue life estimation method considering plate thickness
effect
Evaluation of thickness exponent through fatigue test for T-joint
Development of structural health monitoring system using smart material Direct stress intensity factor measurement during fatigue crack growth
using the MFC sensor
Fatigue life estimation of structure using MFC sensor
Project No. 2-1: Reliability and strength assessment of core parts and material system
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Results of Topic 1
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Fatigue assessment for various weld joints in LNGC barrier Sloshing impact and thermal loads Fatigue fracture
Fatigue strength of the structural components such as 1st , 2nd barrier in LNG CCS need to be guaranteed
Project No. 2-1: Reliability and strength assessment of core parts and material system
10Project No. 2-1: Reliability and strength assessment of core parts and material system
The inner tank material for LNG tanks Typical materials for 1st ,2nd barrier at low temperature (SUS304L, INVAR)
These materials need to guarantee excellent mechanical properties under the cryogenic temperature of -163°C
No. 96 TypeMark-Ⅲ Type Moss Type
TypeMembrane Independent
GTT MARK Ⅲ GTT NO96-2 MOSS IHI-SPB
TankMaterial SUS304L Invar steel Al alloy (Al5083)
Thickness 1.2mm 0.7mm 50mm 30mm
Insulationsystem
Material R-PUFPlywood +
PerlitePUF PUF
Thickness 250mm 530mm 250mm 200mm
11Project No. 2-1: Reliability and strength assessment of core parts and material system
Assessment of cryogenic fatigue performance for LNG cargo tank Characterization of fatigue strength for 1st ,2nd barrier at cryogenic
temperaturePart Temperature
Primary barrier -163°C
Secondarybarrier -110°C
Mastic -40°C
<1st barrier of Mark Ⅲ type>
12Project No. 2-1: Reliability and strength assessment of core parts and material system
Assessment of fatigue strength for various welded joints in LNG cargo tank
INVAR-INVAR joint
SUS304-INVAR joint
INVAR-INVAR joint
13Project No. 2-1: Reliability and strength assessment of core parts and material system
Assessment of fatigue strength by hotspot stress approach
<INVAR-INVAR joint>
<SUS304-INVAR joint><INVAR-INVAR lap joint>
14Project No. 2-1: Reliability and strength assessment of core parts and material system
Assessment of fatigue strength by Notch stress approach
<INVAR-INVAR joint>
<SUS304-INVAR and INVAR-INVAR lap joint>
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Results of Topic 2
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Very thick plates required to offshore structures compared to commercial ships Increase in plate thickness causes decrease of fracture toughness
Strict requirement on the safety and reliability of the offshore structures operating under very extreme conditions Demand to thicker, higher performance, and better toughness
Project No. 2-1: Reliability and strength assessment of core parts and material system
<Offshore structures operating at cryogenic temperature>
Plane stress(Thin)
Plane strain(Thick)
Fra
ctu
re t
ou
gh
nes
s (
)
Plate thickness
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Assessment for fracture toughness to offshore structural steel based on BS 7448
Project No. 2-1: Reliability and strength assessment of core parts and material system
Notch locations Thickness Width Span length Notch length
WM CGHAZ SCHAZ
76 76 294 33
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Evaluation of fracture toughness at low temperature The fracture tests were carried out to obtain CTOD value
DBTT of API 2W Gr.50 is
Weld metal : -75°C CGHAZ : -40°C SCHAZ : -60°C
The fracture toughness of API 2W Gr.50 is higher than that of EH40
Project No. 2-1: Reliability and strength assessment of core parts and material system
<DBTT, EH40> <DBTT, API 2W Gr.50>
A well-known general relation between J and CTOD is
ymJ J : J integral
m : Plastic Constraint Factor (PCF)
: Yield strength
: CTODy
[SINTAP Report]
[ASTM E1820]
Comparison of PCFs b/w analytical and experimental values
Analytical PCF is higher than experimental PCF at low temperature
Analytical PCF does not consider characteristic of welding zone
Analytical PCF require calibration considering low temperature and welding zone
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Results of Topic 3
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Cleveland, Ohio LNG disaster -1944 Caused by 3.5% Ni steel
Since the disaster, Ni amount has been
increased to 9% from 3.5%
Current 9% Ni for SPB cargo tanks $50 million/tank
25% weld material($12.5million)
Weld material
• KOBE $93,200/ton
• UTP $50,000/ton
Replacing by 7% Ni Decrease of the cost for base metals and weld materials
Project No. 2-1: Reliability and strength assessment of core parts and material system
Fracture characteristic for base metal
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Fatigue strength assessment of 7% Ni steel
Assessment of fatigue performance characterized by S-N curve
Fatigue strength characterization with respect to various conditions
Evaluation of fatigue crack initiation and propagation characteristics
Characterization of failure modes for base/weld metals
Project No. 2-1: Reliability and strength assessment of core parts and material system
crack initiation
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Fracture characteristics assessment of 7% Ni steel
Evaluation of fracture toughness of welded joints by CTOD tests
Observation of unstable crack propagation behavior and brittle fracture
Characterization of failure modes for base/weld metals
Investigation of fracture resistance for various welding process
Project No. 2-1: Reliability and strength assessment of core parts and material system
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Fatigue crack growth rate assessment of 7% Ni steel
Evaluation of fatigue crack growth rate for 7% Ni steel
Fatigue crack growth rate test at Cryogenic temperature
Comparison of fatigue crack growth rate for 7% Ni steel and 9% Ni steel
Project No. 2-1: Reliability and strength assessment of core parts and material system
<da/dN curve for 7% Ni steel> <da/dN curve for 9% Ni steel>
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Results of Topic 4
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Thickness effect decreases the fatigue strength for welded structures TR Gurney has proposed thickness exponent 0.25 in 1982
Project No. 2-1: Reliability and strength assessment of core parts and material system
Sref : fatigue strength of plate thickness tref (MPa)tref : reference plate thicknessZ : Thickness exponent
StandardReference
thickness (mm)Thickness exponent
Department of Energy, UK
22 0.25
BS7608 16 0.25
Standards Association of Australia (SAA)
25 0.25
EUROCODE 2 25 0.25
Many standards have used
thickness exponent 0.25
Various welded joints should be considered for calculation of thickness exponent
28Project No. 2-1: Reliability and strength assessment of core parts and material system
Investigation of thickness exponent based on various literatures and fatigue test data Reference fatigue test data
(SR202 project, Xial et al., deBack et al., Webster, Vosilovsky, UKOSRP)
PNU fatigue test data
Calculation of thickness exponent for 6 step fatigue life
(100,000 / 500,000 / 1,000,000 / 2,000,000 / 5,000,000 / 10,000,000 cycles)
10 10010
100
1000
100,000 Cycle 500,000 Cycle 1,000,000 Cycle 2,000,000 Cycle 5,000,000 Cycle 10,000,000 Cycle
Fat
igu
e S
tre
ngth
(M
Pa)
Thicness (mm)
29Project No. 2-1: Reliability and strength assessment of core parts and material system
105 106 107
0.20
0.25
0.30
0.35
0.40
0.45
0.50
Th
ickn
ess
exp
on
en
t
Cycle
Calculation of thickness exponent considering fatigue life
Thickness exponent for 2,000,000 cycles is similar to IIW thickness
exponent for T-joint
But, thickness exponent decreased as decreasing fatigue life
Cycles Thickness exponent
100,000 0.296
500,000 0.343
1,000,000 0.346
2,000,000 0.384
5,000,000 0.411
10,000,000 0.413
IIW document Thickness correction
As-welded T-joints(proportional joints) subjected to bending load
0.33
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Results of Topic 5
31Project No. 2-1: Reliability and strength assessment of core parts and material system
Structural health monitoring system (SHM) Purpose to inform hazard of ship/offshore structure (fatigue, impact load)
Assessment of structural integrity for welded structures
Fatigue fracture occurs due to exposure to constant fatigue load Increase in importance for fatigue
crack detection technology
Reliable structural integrity evaluation
method is needed
Development of structural health
monitoring system for defect inspection
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Hull response monitoring systems
Fatigue monitoring sensors
Airgap sensing system
Corrosion monitoring system
Acoustic emissions monitoring sensors
Vibration based damage assessment approaches
Fiber optic sensors
Riser and anchor chain monitoring
Project No. 2-1: Reliability and strength assessment of core parts and material system
Slit
Grating
33Project No. 2-1: Reliability and strength assessment of core parts and material system
MFC sensors is used for the real-time measurement of the stress intensity factor The tendency of analytical SIF as growing fatigue crack is similar to
experimental one
The Stress Intensity Factor(SIF) is required for the estimation of fatigue crack propagation life from the Linear Elastic Fracture Mechanics(LEFM)
(Paris law)
34Project No. 2-1: Reliability and strength assessment of core parts and material system
Publications International Journal (SCI)
• Total 7 items
Conference Presentation
• Total 8 items
Education MS Graduate
• 6 persons
Ph. D. Graduate
• 1 person
Author Paper Journal
Hyeon-Su Kim,
Min-Sung Chun,
Myung-Hyun Kim,
Jae-Myung Lee
A Comparative Evaluation of Fatigue and Fracture Characteristics of
Structural Components ofLNGC Insulation System
International Journal of
Pressure Vessel Technology
Author Conference Title City Nation
Seong Min Kim,
Jae Myung Lee,
Myung Hyun Kim
SNAME 2011Fatigue Assessment of a Bulk Carrier using the
Mesh-insensitive Structural Stress based on CSRHouston USA
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Industry-University Liaison Research Grant
• Connector and joint strength assessment of riser (2012.03 ~ 2014.12, PNU-DSME)
• JDP for assessment of 7% Ni steel cargo tank in LNGC and FLNG
(2011.7 ~ 2013.06, PNU-NK,HHI)
• Assessment of fatigue performance of bonded connection structure
(2012.03 ~ 2013.02, PNU-SHI)
• Assessment of high temperature durability for epoxy and PU glue
(2012.09 ~ 2013.02, PNU-SHI)
• Fatigue test for 1st, 2nd barrier of HHI CCS (2011.02 ~ 2013.02, PNU-HHI)
Intellectual Properties Pending
• A Jig for the tensile and fatigue tests of thin plates at the cryogenic temperature
(2011.10)
• Anti-sloshing method using fluid rotation (2011.10)
Project No. 2-1: Reliability and strength assessment of core parts and material system
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