This course discuss different advanced methods for fatigue design of welded structures; Nominal stress method, Hot Spot (geometric/structural) Stress method, Effective Notch Stress method and applied linear elastic fracture mechanics (LEFM). Influence of different factors that effect the fatigue life and breakdown is discussed, such as; stress concentrations, weld defects, welding residual stresses, multiaxial stresses, etc..
Content and learning outcomes
Intended learning outcomes
This course discuss different advanced methods for fatigue design of welded structures; Nominal stress method, Hot Spot (geometric/structural) Stress method, Effective Notch Stress method and applied linear elastic fracture mechanics (LEFM). Influence of different factors that effect the fatigue life and breakdown is discussed, such as; stress concentrations, weld defects, welding residual stresses, multiaxial stresses, etc.. Different post weld improvement techniques in order to increase the quality and the fatigue strength of welded structures is discussed. Different weld class system in order to assure the weld quality of welded joints in the design and during production is discussed and compared. Different design codes, guidelines for practice and recommendations for welded jonits are discussed e.g. IIW:s “recommendations for fatigue design of welded jonits and components”. Evaluation and fatigue design of welded structures using FEM is treated regarding; boundary conditions, accuracy, non-linearity, sub-modelling techniques, 3D effects. Different state-of-the-art applied fracture mechanical softwares for prediction of the fatigue life of welded jonits is presented, discussed and utilized.
In order to guarantee thestrength of a welded structure different design codes have been developed during the last 30 years and have been applicable within the manufacturing industry with low accuracy and precision. As the Finite Element Analysis is nowadays a widley used tool new developed design codes are applicable with better accuracy and precision. After the course the students should be able to:
- Chose method for fatigue life assessment accuracy for different types of welded jonits and structures.
- Perform two dimensional welding simulations in order to predict the residual stresses and distortion due to welding.
- Understanding the effect of welding residual stress on the structural integrity.
- Use appropriate fracture mechanical software in the fatigue design of welded jonits (e.g. Franc2D, Afgrow).
- Understand the influence of different types of weld defects and discontinuities on the fatigue strength of welded jonits.
- Perform fatigue life assessment of complex welded structures.
- Chose relevant post weld improvement techniques for different welded applications.
- Use weld quality systems.
The course runs parallel with the undergraduate course SD2420.
PhD graduate course (FSD3400) contains additional tasks.
Literature and preparations
FEM (ANSYS), Linear elastic fracture mechanics (LEFM) and basic knowledge in solid mechanics, material mechanics and fatigue.
Ett för ändamålet nyskrivet kurskompendium kommer att delas ut. Utdelade artiklar. Utdrag ur standarder, koder och normer. Rekommendation av litteratur för ytterligare studier kommer att meddelas vid kursstart.
A special written course compendium will be handed out. Extract from Articles, standard and design codes will be handed out. Recommended literature for further reading will be announced at the course start.
Examination and completion
If the course is discontinued, students may request to be examined during the following two academic years.
- INL1 - Assignment, 3.0 credits, grading scale: G
- LAB1 - Laboratory work, 3.0 credits, grading scale: G
Based on recommendation from KTH’s coordinator for disabilities, the examiner will decide how to adapt an examination for students with documented disability.
The examiner may apply another examination format when re-examining individual students.
Other requirements for final grade
3 exercises on fatigue design with FEM: examination; results presented at the lab occasion.
1 extended home assignment/casestudy: fatigue design of welded structures: examination; written report.
2 extended home assignment in fatigue design of welded structures using LEFM and FEM: examination; written report.
Opportunity to complete the requirements via supplementary examination
Opportunity to raise an approved grade via renewed examination
- All members of a group are responsible for the group's work.
- In any assessment, every student shall honestly disclose any help received and sources used.
- In an oral assessment, every student shall be able to present and answer questions about the entire assignment and solution.
Further information about the course can be found on the Course web at the link below. Information on the Course web will later be moved to this site.Course web FSD3400