Fatigue design and analysis of steel structures. Basic course

Dato: 26-10-2016-27-10-2016 | Påmeldingsfrist: 21-10-2016

This course provides a general introduction to fatigue of welded structures and machine components. Typical fatigue failures are reviewed and the causes are discussed. Important factors that determine fatigue endurance are explained. Basic aspects of fatigue crack initiation and the propagation of cracks are treated and life prediction methodologies are illustrated. Special topics regarding fatigue of offshore structures and windmills are covered in the course.

Course content:
• Examples of fatigue failures
• Dominating factors that influence fatigue life
• Stress concentrations and defects
• Thickness effects
• Environmental effects
• Fatigue testing and S-N curves
• Loading data and stress spectra
• Fatigue design methods:  
- Nominal stress  
- Local stress  
- Fracture mechanics
• Design rules and standards, e.g. NORSOK, DNV, Eurocode 3, IIW
• Worked examples and problems

The course is suitable for engineers who need a basic introduction to fatigue and fatigue life evaluation of machine components and welded structures.


Day 1

08.30 Registration and refreshments

Part 1: Basic aspects of fatigue

09.00 Introduction: Historical examples of fatigue failures
• What is fatigue and how do fatigue cracks start?
• Examples:
- Machine components
- NSB railway axle shaft
- Welded structures: The A. L. Kielland failure

10.00 Fatigue strength – main influencing factors during crack initiation
• Fatigue loading
• Geometry
- stress concentrations
• Loading conditions: Tension, bending, torsion, influence of mean stress
• Material effects
– low strength and high strength steels, stainless steel, aluminium, titanium
• Surface condition and residual stresses
• Size and volume effects
• Effect of corrosion and corrosion protection
• Effect of temperature – arctic conditions

10.45 Break

11.00 Fatigue strength – main influencing factors for welded structures
• Fracture mechanics and crack propagation
• Material data, S-N curves, Paris’ law
• Fabrication and fatigue strength
- Weld geometry and weld defects
- Welding methods and weld quality
- Inspection
• Weld classes
• Modification of S-N curves:
Thickness, low and high cycle fatigue, misalignment

12.00 Lunch

13.00 Trender innen FoU – utmatting av offshorekonstruksjoner
• Arktiske forhold
• Strain-baserte metoder
• Forskning og utvikling innen designregler - DNV og ISSC
siv.ing. Agnes M. Horn, DNV GL, Høvik

13.30 Life extension by upgrading and repair
• Life extension by improved design
• Post weld improvement methods
- Improved materials

14.30 Fatigue strength data from testing
• Plate connections
• Pipes and tubular joints
• Non-welded components
• The endurance limit, S-N curve extrapolation and cut-off
• Scatter, statistical analysis and determination of design data

15.00 Break

15.15 Fatigue life evaluation
• Loading data, stress spectra
• Palmgren-Miner rule – cumulative fatigue
• Life calculation methods:  
- Nominal stress  
- Hot spot stress  
- Effective notch stress  
- Fracture mechanics Examples and exercises

16.30 Summary and discussion

17.00 End - Part 1

Day 2

Part 2: Design rules - fatigue

08.30 Design rules, overview
• Non-welded components  
- EN 13445 Pressure vessels  
- FKM Machine components
• Welded structures  
- DNV and Norsok (offshore structures)  
- BS7608 (welded structures – general rules)  
- Eurocode 3 (welded structures – land based)  
- IIW (welded structures – general rules)  
- ISO 19902(offshore structures)

10.00 Review of Eurocode 3, Part 1-9
• Applications - NAD
• Fatigue life prediction methods
• ECCS Design manual for fatigue design

10.30 Break

11.45 Comparison of Eurocode 3 with other design rules - IIW og DNV RP–C203

12.30 Lunch

Part 3: Examples and exercises

13.30 Fatigue of windmills
• Types of windmills
• Load analysis - Rainflow counting
• Stress analysis and life assessment
Arne Ivar Hansen, TDA, Oslo

14.00 Examples and exercises – machine structures

14.30 Break

14.45 Examples and exercises – welded structures

16.00 Summary and discussion

16.30 End 


Practical info and registration

Date: 26 - 27. October 2016
: Felix Konferansesenter, Aker Brygge, Oslo

Registration fee: incl. lunch and coffee breaks
NOK 9.200 for members of NFS and/or Norsk Stålforbund
NOK 9.700 for non-members

The course includes e-cours compendium The folloing standards can be useful for the course:
* NORSOK N-006 here
* DNV-RP-C203 (Fatigue of offshores structures) here 
Eurocode 3, part 1-9, may be ordered here    

Norsk Stålforbund, e-mail: post@stalforbund.com, tel.: +47 41 02 15 98

Norsk Stål
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