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Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
SERKAN BIRINCI
M.Sc. International Production Management
Prof. Dr. -Ing. Wolfgang Fricke, TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
15 September 2008
EXPERIMENTAL AND NUMERICAL FATIGUE STRENGTH INVESTIGATION OF A WELDED
STRUCTURE AND ASSESSMENTWITH DIFFERENT APPROACHES
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Main Aim
• To assess the fatigue strength of four different structural details by applying different
fatigue assessment methods
• Comparison of these methods according to the applicability for a specific detail
Introduction Theoretical Background Experimental Setup Results Conclusion
Page 1
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Fatigue FailureThe progressive and localized structural damage that occurs when a material is
subjected to a cyclic loading.
Steps of Crack Formation• Crack Initiation
• Crack propagation
• Final Fracture
Major Influences on Fatigue Strength• Local Parameters of Geometry : Toe Radius, Weld Angle and Surface Crack Depth
• Loading : Fluctuating and Repeating
• Material Type
• Fusion Process, Residual Stresses
• Stress Concentration Effects : Key way, Hole and Non-welded Root Gaps
Introduction Theoretical Background Experimental Setup Results Conclusion
Page 2
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Fatigue Assessment Approaches
Page 3
• Global Approaches
- Nominal Stress Method
• Local Approaches
- Structural Hot Spot Stress Method
- Effective Notch Stress Method
• Linear Elastic Fracture Mechanics Approach
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Fatigue Assessment Approaches
• Global Approaches
- Nominal Stress Method
• Local Approaches
- Structural Hot Spot Stress Method
- Effective Notch Stress Method
• Linear Elastic Fracture Mechanics Approach
Nominal Stress Classes
Number of Cycles (N)
∆σ[M
Pa]
Page 4
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Fatigue Assessment Approaches
• Global Approaches
- Nominal Stress Method
• Local Approaches
- Structural Hot Spot Stress Method
- Linear Stress Extrapolation
- According to Xiao and Yamada
- Effective Notch Stress Method
• Linear Elastic Fracture Mechanics Approach
Page 5
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Fatigue Assessment Approaches
• Global Approaches
- Nominal Stress Method
• Local Approaches
- Structural Hot Spot Stress Method
- Linear Stress Extrapolation
- According to Xiao and Yamada
- Effective Notch Stress Method
• Linear Elastic Fracture Mechanics Approach
Page 6
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Fatigue Assessment Approaches
• Global Approaches
- Nominal Stress Method
• Local Approaches
- Structural Hot Spot Stress Method
- Effective Notch Stress Method
• Linear Elastic Fracture Mechanics Approach
Page 7
RADIUS 1 mm
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Fatigue Assessment Approaches
• Global Approaches
- Nominal Stress Method
• Local Approaches
- Structural Hot Spot Stress Method
- Effective Notch Stress Method
• Linear Elastic Fracture Mechanics Approach
Page 8
IK = . .a Yσ π
• KIC = Fracture Toughness
• KI = Stress Intensity Factor
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Relation Between Stresses
Base Plate
Cover Plate
Strengths and Weaknesses of the Methods
Nominal Stress Method
- Local geometry properties not evaluated
- But included in detail classes and S-N curves
Structural Stress Method
- Omits the detail classes
- Captures the local macro geometric effects
- Excludes the notch effect
Effective Notch Stress Method
- Includes the effect of local weld toe geometry
n
kmax
max
I
= Nominal Stress
= Maximum Notch Stress
= Maximum Structural Stress
K = Stress Intensity Factor
s
σ
σ
σ
Page 9
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Specification of Specimens
• 4 cases ( each of 10 Specimens )
- Size : 300 mm × 50 mm × 12 mm
- Weld Throat Length (a) : 3 mm and 7 mm
- Loading Type : Load Carrying and Non-Load Carrying
SECTION A-A
Lc / 2
T
T/2
Lw
a
F
Page 10
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Specification of Experiment
• The Applied Repeated Nominal Stress
- 90 MPa – 120 Mpa for 3 mm Load Carrying Fillet Weld Joint
- 120 MPa – 170 Mpa for 3 mm Non-Load Carrying Fillet Weld Joint
- 120 MPa – 210 Mpa for 7 mm Load Carrying Fillet Weld Joint
- 150 MPa – 200 Mpa for 7 mm Non-Load Carrying Fillet Weld Joint
• Frequency : 30 Hz
• Stress Ratio, R = 0
Page 11
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Observed Crack Formation
Page 12
TOE
CRACK
ROOT
CRACK
a
ROOT
CRACK
a
TOE
CRACK
a
TOE
CRACK
a
3 mm a-Length
Load Carrying Fillet Weld
3 mm a-LengthNon-Load Carrying
Fillet Weld
7 mm a-Length
Load Carrying
Fillet Weld
7 mm a-Length
Non-Load Carrying Fillet Weld
σ σ
σ σ σ σ
σ σ
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Observed Crack Formation
Weld root crack in 3 mm
load carrying fillet weld joint
Page 13
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Test Results for Nominal Stress Method
S - N RESULTS OF THE FATIGUE TEST
54.7
10
100
1000
1.E+04 1.E+05 1.E+06 1.E+07
Number of Cycle ( N )
Stress Range ( N/m
m2)
Pü=10%
Pü=50%
Pü=90%
Pü=97.7%
3mm Load Carrying Fillet Weld - Crack at Weld Root
7mm Load Carrying Fillet Weld - Crack at Weld Toe
3mm Non-Load Carrying Fillet Weld - Crack at Weld Root and Weld Toe
7mm Non-Load Carrying Fillet Weld - Crack at Weld Toe
Page 14
Stress Range (N / m
m2)
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Investigated Variables3 mm throat length
• Weld size 7 mm throat length
Load carrying weld• Loading type
Non-load carrying weld
• Effect of contact analysis in FEM program (ANSYS)
Assumptions for FEM Model
• Assumption of specimen
- Flank angle of 135 ˚
- Weld Toe Radius 1 mm
- Throat thickness of 3 mm and 7 mm
• Assumption of FEM model
- Plane stress condition
- 90 MPa Nominal Stress
- Restraints applied end of the main plate
Page 15
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Structural Hot Spot Stress Method by Linear Extrapolation
AXIAL STRESS
( m m )0 T 0,4 T 1,0 T
0 T
a) Coarse Mesh
c) Coarse Mesh Refined
b) Finer Mesh
d) Finer Mesh Refined
Page 16
• 3 mm and 7 mm throat thickness
are insensitive to non-linear peak
stress
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
LINEAR STRESS EXTRAPOLATION AT THE WELD TOE
88000
90000
92000
94000
96000
98000
100000
102000
104000
106000
108000
00.20.40.60.81
DISTANCE (T)
AXIAL STRESS
L3_Non-Load Carrying Coarse MeshL7_Non-Load Carrying Coarse MeshL3_Non-Load Carrying Coarse Mesh RefinedL7_Non-Load Carrying Coarse Mesh RefinedL7_Non-Load Carrying Finer MeshL3_Non-Load CarryingL7_Non-Load CarryingL3_Load CarryingL7_Load Carrying
3 mm load carrying
7 mm load carrying
Page 17
Structural Hot Spot Stress Method by Linear Extrapolation
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
1 mm
Introduction Theoretical Background Experimental Setup Results Conclusion
Structural Hot Spot Stress Method by Xiao and Yamada
Page 18
Notch Stress Modeled
1 mm mesh size Modeled
1 mm
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Structural Hot Spot Stress Method by Xiao and Yamada
Page 19
10
100
1000
1.E+05 1.E+06 1.E+07
Number of Cycle ( N )
Structural Stress at 1 m
m Depth ( M
pa )
R = 0
FAT 100
3mm Non-Load Carrying without contact analysis, Ks= 1.21,Weld Toe Crack 3mm Non-Load Carrying with contact analysis, Ks= 1.27,Weld Toe Crack7mm Load Carrying without contact analysis, Ks = 1.34,Weld Toe Crack 7mm Load Carrying with contact analysis, Ks = 1.24,Weld Toe Crack 7mm Non-Load Carrying without contact analysis, Ks = 1.19,Weld Toe Crack 7mm Non-Load Carrying with contact analysis, Ks = 1.16,Weld Toe Crack
WÖHLER S-N CURVEFORMED WITH
AXIAL STRESS σX Notch Stress Modeled
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Structural Hot Spot Stress Method by Xiao and Yamada
Page 20
10
100
1000
1.E+05 1.E+06 1.E+07
Number of Cycle ( N )
Structural Stress at 1 m
m Depth (Mpa)
R = 0
FAT 100
3mm Non-Load Carrying, without contact analysis, Ks= 1.37, Weld Toe Crack 3mm Non-Load Carrying, with contact analysis, Ks= 1.46, Weld Toe Crack7mm Load Carrying, without contact analysis,Ks = 1.63, Weld Toe Crack7mm Load Carrying, with contact analysis,Ks = 1.42, Weld Toe Crack7mm Non-Load Carrying, without contact analysis, Ks = 1.31, Weld Toe Crack7mm Non-Load Carrying, with contact analysis, Ks = 1.25, Weld Toe Crack
WÖHLER S-N CURVEFORMED WITH
PRINCIPAL STRESS σ1 Notch Stress Modeled
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Structural Hot Spot Stress Method by Xiao and Yamada
Page 21
10
100
1000
1.E+05 1.E+06 1.E+07
Number of Cycle ( N )
Structural Stress at 1 m
m Depth (Mpa)
R = 0
FAT 100
3mm Non-Load Carrying, without contact analysis, Ks= 1.06, Weld Toe Crack 3mm Non-Load Carrying, with contact analysis, Ks= 1.11, Weld Toe Crack7mm Load Carrying, without contact analysis, Ks= 1.20, Weld Toe Crack7mm Load Carrying, with contact analysis, Ks= 1.12, Weld Toe Crack7mm Non-Load Carrying, without contact analysis, Ks= 1.10, Weld Toe Crack7mm Non-Load Carrying, with contact analysis, Ks= 1.07, Weld Toe Crack
WÖHLER S-N CURVEFORMED WITH
AXIAL STRESS σX
1 mm mesh size Modeled
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Structural Hot Spot Stress Method by Xiao and Yamada
Page 22
10
100
1000
1.E+05 1.E+06 1.E+07
Life Cycle ( N )
Structural Stress at 1 m
m Depth (Mpa)
R = 0
FAT 100
3mm Non-Load Carrying, without contact analysis, Ks= 1.20, Weld Toe Crack 3mm Non-Load Carrying, with contact analysis, Ks= 1.26, Weld Toe Crack7mm Load Carrying, without contact analysis, Ks= 1.50, Weld Toe Crack7mm Load Carrying, with contact analysis, Ks= 1.27, Weld Toe Crack7mm Non-Load Carrying, without contact analysis, Ks= 1.23, Weld Toe Crack7mm Non-Load Carrying, with contact analysis, Ks= 1.16, Weld Toe Crack
1 mm mesh size Modeled
WÖHLER S-N CURVEFORMED WITH
PRINCIPAL STRESS σ1
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Structural Hot Spot Stress Method by Xiao and Yamada
Page 23
1 mm mesh
size ModeledNotch Stress
Modeled
• All compared parameters of notch stress modeled mesh give higher values
than 1 mm mesh size model.
• Not having 1 mm fictitious radius causes increased stresses at the plate edge
of 1 mm mesh size model, and correspondingly causes decreased stresses.
• Xiao and Yamada SHS Stress Approach highly sensitive to mesh size at the weld toe.
• All the stress values of contact analysis used 1 mm mesh size model are
higher than without contact analysis used.
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Effective Notch Stress Method
Page 24
Notch Stress Modeled Fictitious notch radius rf = 1 mm
Fictitious radius rf = 1 mm
R1
R1• All principal stresses were taken from
the points in where the crack formation
occurred in the real test specimen.
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Effective Notch Stress Method
Page 25
10
100
1000
1.E+05 1.E+06 1.E+07
Number of Cycle ( N )
Effective Notch Stress Range (Mpa)
R = 0
3 mm Load Carrying Fillet with contact analysis Kf = 7.50, Weld Root Crack3 mm Load Carrying Fillet without contact analysis Kf = 6.38 , Weld Root Crack3mm Non-Load Carrying with contact analysis, Kf = 3.50, Weld Toe Crack3mm Non-Load Carrying without contact analysis Kf = 3.40, Weld Toe Crack3mm Non-Load Carrying with contact analysis, Kf = 3.73, Weld Root Crack3mm Non-Load Carrying without contact analysis Kf = 2.28, Weld Root Crack7mm Load Carrying wih contact analysis, Kf = 3.27, Weld Toe Crack7mm Load Carrying without contact analysis Kf = 3.96, Weld Toe Crack7mm Non-Load Carrying wih contact analysis, Kf = 2.76, Weld Toe Crack7mm Non-Load Carrying without contact analysis Kf = 2.96, Weld Toe Crack
FAT 225 ( m = 3 )
• Design assign curve
with FAT 225
• Highest Kf value obtained
3 mm Load Carrying Fillet
Weld
• Lowest Kf value obtained
3 mm Non-Load Carrying
Fillet Weld
• The contact analysis result
of 3 mm fillet weld higher
than the without contact
analysis
• The contact analysis
result of 7 mm fillet weld
lower than the without
contact analysis
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Effective Notch Stress Method
Page 26
With Contact
Analysis
Without Contact
Analysis
• Maximum Stress at
the Weld root
• Maximum Stress at
the Weld Toe
• 3 mm fillet weld with the contact analysis
conducts bending forces from the weld toe to
weld root
• Contact effect increases the effective notch
stress in the weld toe
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Linear Elastic Fracture Mechanics
Page 27
With Contact
Analysis
• FRANC2D crack growth program used to evaluate the fatigue life of 3 mm throat
thickness Load carrying and Non-Load carrying weld model
• Plane stress assumption
• To prove the accuracy of program, a test was done with a very simple specimen with
0.5 mm and 1.0 mesh size. Then,result compared with analytical result.
a0= 0.1 mm C = 5.21·10-13
∆a = 0.1 mm KIC = 2245 [N/mm3/2]
P = 90 Mpa m = 3.0
IK = . .a Yσ π
/ 2 / 2 1 / 2 10
1 1 1
( / 2 1)m m m m me
NC m Y a aσ π − −
= −
⋅ ∆ ⋅ − ⋅ ⋅
/ 2 / 2 1 / 2 1
1 1 1
( / 2 1) ( ) ( )m m m m mc c
NC m Y a a a aσ π − −
∆ = − ⋅ ∆ ⋅ − ⋅ ⋅ + ∆
(1)
(2)
(3)
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Linear Elastic Fracture Mechanics
Page 28
With Contact
Analysis
• Mode I SIF graphs calculated by FRANC2D program and by analytically
• not insensitive to mesh size
• SIF of 1 mm mesh size test model resulted nearly %10 higher value than 0.5 mm
mesh size test modelMODE I SIF HISTORY
-100.000
100.000
300.000
500.000
700.000
900.000
0.000 1.000 2.000 3.000 4.000 5.000
Crack Length
KI
FRANC2D ANALYTICAL
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Linear Elastic Fracture Mechanics
Page 29
With Contact
Analysis
• Fatigue life graphs calculated by FRANC2D program and by analytically
• fatigue life time increased nearly %40, due to 1mm mesh size
NUMBER OF CYCLES vs. CRACK LENGTH
-2.000E+05
2.000E+05
6.000E+05
1.000E+06
1.400E+06
1.800E+06
0.000 1.000 2.000 3.000 4.000 5.000
CRACK LENGTH ( mm )
NUMBER OF CYCLES ( N )........
FRANC2D ANALYTICAL
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Linear Elastic Fracture Mechanics
Page 30
With Contact
Analysis
• Fatigue life and SIF graphs of 3 mm Load and Non-Load carrying Fillet Weld
Non-Load Carrying Weld Load Carrying Weld
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Page 31
Conclusions
• When the weld throat thickness of the specimens increases, the crack formation passes from weld
root to weld toe
• The applicability of Structural Hot Spot (SHS) method by Linear Stress Extrapolation
is relatively easier than other methods
• Weld Size variation causes inconsistent results, the SHS method is sensitive to mesh size
• The effects of weld size variation is most clearly seen in Effective Notch Stress Method, and least
seen Xiao and Yamada SHS Stress Method
• The obtained principal stresses in Xiao and Yamada SHS Stress Method are higher than axial
stresses
• All compared parameters of notch stress modeled mesh in Xiao and Yamada SHS Stress Method
result higher stress values than 1 mm mesh size model
• Xiao and Yamada SHS Stress Method is highly sensitive to mesh size at the weld toe
• FRANC2D is sensitive to mesh size, and uses numerical integration to calculate fatigue life.
Therefore, correct mesh size of the model is important.
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Page 31
Future Works
• Stress distribution with the variation of the local shape of the weld, the weld toe radius, flank
angle and the mesh size by Xiao and Yamada Method
• Exact mesh size with the calculation of FRANC2D for the 7 mm load carrying and non-load
carrying fillet weld
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Page 32
THANK YOU FOR YOUR ATTENTION
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Test Results for Nominal Stress Method ( Separated)
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
S - N RESULTS OF THE FATIGUE TESTLoad Carrying 3mm a-length
Weld Root
10
100
1000
10000
1.E+04 1.E+05 1.E+06 1.E+07
Life Cycle ( N )
Stress Range
( Mpa )
3mm Load Carrying Fillet Weld - Crack at Weld Root
Pü=10%
Pü=50%
Pü=90%
Pü=97.7%
R = 0
40.1
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Test Results for Nominal Stress Method ( Separated)
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
S - N RESULTS OF THE FATIGUE TESTNon-Load Carrying 3mm a-length
Weld Toe
10
100
1000
1.E+05 1.E+06 1.E+07
Life Cycle ( N )
Stress Range ( Mpa )
3mm Non-Load Carrying Fillet Weld - Crack at Weld Toe
Pü=10%
Pü=50%
Pü=90%
Pü=97.7%
R = 0
75.3
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Test Results for Nominal Stress Method ( Separated)
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
S - N RESULTS OF THE FATIGUE TESTNon-Load Carrying 3mm a-length
Weld Root
10
100
1000
1.E+05 1.E+06 1.E+07
Life Cycle ( N )
Stress Range ( Mpa )
3mm Non-Load Carrying Fillet Weld - Crack at Weld Toe
Pü=10%
Pü=50%
Pü=90%
Pü=97.7%
R = 0
68.8
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Test Results for Nominal Stress Method ( Separated)
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
S - N RESULTS OF THE FATIGUE TESTLoad Carrying 7 mm a-length
Weld Toe
10
100
1000
1.E+05 1.E+06 1.E+07
Life Cycle ( N )
Stress Range ( Mpa )
7 mm Load Carrying Fillet Weld - Crack at Weld Toe
Pü=10%
Pü=50%
Pü=90%
Pü=97.7%
R = 0
82.4
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
Introduction Theoretical Background Experimental Setup Results Conclusion
Test Results for Nominal Stress Method ( Separated)
Prof. Dr. -Ing. Wolfgang Fricke , TUHH
Prof. Dr. -Ing. Uwe Weltin, TUHH
Dipl. -Ing. Olav Feltz, TUHH
Serkan Birinci15 September 2008
Konstruktion und Festigkeit von Schiffen
S - N RESULTS OF THE FATIGUE TESTNon-Load Carrying 7 mm a-length
Weld Toe
10
100
1000
1.E+05 1.E+06 1.E+07
Life Cycle ( N )
Stress Range ( Mpa )
7 mm Load Carrying Fillet Weld - Crack at Weld Toe
Pü=10%
Pü=50%
Pü=90%
Pü=97.7%
R = 0
75.4