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Application of Web-Based Bar Fatigue Database
Database Development
Thomas G. Oakwood
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Bar Steel Fatigue Database-Objectives
• Develop a strain-controlled fatigue database for carbon and low alloy bar steels for the automotive and OEM industries
• Provide fatigue data which can be used to predict and analyze service life for chassis, engine and drive train components
• Utilize a directly accessible Internet-based format
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• AISI Bar Steel Producers• Automotive Manufacturers• OEM Suppliers• Two Universities
– University of Toledo– University of Waterloo
Bar Steel Fatigue Database-Participants
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• Steel Characterization– Composition– Processing History– Microstructure
• Mechanical and Cyclic Properties– Tabulation of Axial Fatigue Data
• Graphical Output of Monotonic and Cyclic Stress-Strain Curves and Strain-Life Curves
Bar Steel Fatigue Database-Information
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• Direct-Access Internet Format• Multiple Screens
– Master Index– “Tabbed” Material Properties Screens– Report Format– Excel– SAE– Independent Access for Microstructures and Graphs
• Comparative Printing
Bar Steel Fatigue Database-Format
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Iteration Number 18
SAE Steel Grade 1038
Process Normalized 1650
Steel Making Practice
Basic Oxygen Yes
Electric Furnace No
Vacuum Degas No
Ladle Refined Yes
Casting Practice
Ingot Cast No
Continuous Cast Yes
Billet Size (mm)
Bloom Size (mm) 300 X 600
Bar Steel Fatigue Database-Sample Data
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Bar Steel Fatigue Database-Sample Data
Chemical Properties
Carbon, % 0.40
Manganese, % 0.8
Phosphorous, % 0.013
Sulfur, % 0.024
Silicon, % 0.28
Copper, % 0.03
Nickel, % 0.01
Chromium, % 0.04
Molybdenum, % 0.01
Vanadium, % 0.00
Niobium, % 0.00
Aluminum, % 0.03
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Bar Steel Fatigue Database-Sample Data
Monotonic Properties
Modulus of Elasticity, E, GPa 201
Yield Strength, YS, MPa 330.7
Upper Yield Strength, UYS, Mpa 346.8
Lower Yield Strength, LYS, Mpa 327.2
Yield Point Elongation, YPE % 1.10
Ultimate Strength, UTS, MPa 582.2
Percent Elongation, %EL, 44
Percent Reduction in Area, %RA 54
Strength Coefficient, K, MPa 1,105.7
Strain Hardening Exponent, n 0.260
True Fracture Strength, σf, Mpa* 898
*Corrected for Necking
True Fracture Ductility, εf, % 80.0
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Bar Steel Fatigue Database-Sample Data
Cyclic Properties
Cyclic Yield Strength, YS', MPa 342
Fatigue Strength Coefficient, σf ', MPa 1,039
Fatigue Strength Exponent, b -0.1062
Fatigue Ductility Coefficient, εf ' 0.303
Fatigue Ductility Exponent, c -0.4794
Cyclic Strength Coefficient, K', MPa 1,340
Cyclic Strain Hardening Exponent, n' 0.2198
Fatigue Strength @ 106 Cycles, MPa 222.6
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• “Private Access”– AISI Bar Steel Fatigue Committee Subscribers– Private Access to Data for Two Years– 71 Iterations (26 More in Progress)
• “Public Access”– General Public– Data Available After Two Year Restriction– 43 Iterations Available
• User Name and Password Required
Bar Steel Fatigue Database-Access
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Yung - Li LeeDaimlerChrysler
DaimlerChrysler
Application of Web-Based Bar Fatigue Database
Database Application
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MODERN FATIGUE DESIGN PROCESS
Component/vehicle design
Prototypes build up
Field data acquisition
Data analysis & reduction
CAE models
Load-based fatigue analysis
Loads database
Virtual proving grounds
Sign off
Fatigue testing
CAE analysis
ok
ok
no
no
DaimlerChrysler
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FATIGUE EVALUATION METHOD
Test drive - proving grounds
System test rig -simulators & dynamometers
Component test rig - constant & block cycle tests
Load-life or nominal stress life methods
Local strain life approach
Life
Test
Life
Cal.
Loads
DaimlerChrysler
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ROAD TEST SIMULATORDaimlerChrysler
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STRESS COATING FOR STRESS RAISERS
DaimlerChrysler
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GAGING/WIRING A TRANS CASEDaimlerChrysler
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GAGED TRANS CASE IN-VEHICLE CONDITION
DaimlerChrysler
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GAGING/WIRING A CHANKSHAFTDaimlerChrysler
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GAGED JOUNCE BUMPERDaimlerChrysler
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GAGED SPRINGDaimlerChrysler
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INSTRUMENTED SPRING AND JOUNCE BUMPER
DaimlerChrysler
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GAGED SHOCKDaimlerChrysler
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INSTRUMENTED SHOCK, SPRING AND JOUNCE BUMPER
DaimlerChrysler
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FATIGUE ANALYSIS OF A WELDED CRADLE
Specimen Material Data
F2=
Fn=
F1=
• Channel 1
Results•Damage Values•Endurance Safety Factors•Fatigue Life Time
WELD Database
• Channel 2
• Channel n
FATIGUE ANALYSIS
DaimlerChrysler
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FATIGUE ANALYSIS OF A CYLINDER HEAD
DaimlerChrysler
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Synchronized Kinematic Animation(Courtesy LMS North America)
DaimlerChrysler
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Stress Animation(Courtesy LMS North America)
DaimlerChrysler