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Content and 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). Infleunce of different factors that effect the fatigue life and breakdown is discussed, such as; stress concentrations, weld defects, welding residual stresses, multiaxial stress states, etc. Different post weld improvement techniques in order to increase the weld quality and the fatigue strength of welded structures is duscussed. Different weld class systems in order to assure the weld quality of welded jonits in the design and during production is discussed and compared. Different design codes, guidelines for practice and reccomendations 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.
Intended learning outcomes
In order to guarantee the strength of a welded structures 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 student should be able to:
- Chose method for fatigue life assessment with reasonable accuracy for different types of welded jonits and structures.
- Understand the effects of welding residual stress on the strucutral integrity.
- Understand the influence of different types of weld defects and discontinuities on the the fatigue strength of welded jonits.
- Choose appropriate analysis method and perform fatigue life assessment of complex welded structures.
- Chose relevant post weld improvment techniques for different welded applications.
- Use weld quality systems.
Literature and preparations
FEM, Linear elastic fracture mechanics (LEFM) and basic knowledge in solid mechanics, material mechanics and fatigue.
English B / English 6
Examination and completion
If the course is discontinued, students may request to be examined during the following two academic years.
- BER1 - Assignment 1, 2.0 credits, grading scale: P, F
- BER2 - Assignment 2, 2.0 credits, grading scale: P, F
- LAB1 - Labs and assignments, 2.0 credits, grading scale: P, F
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.
Grading scale P/F
Other requirements for final grade
LAB1 - 3 computerlabs/excercises on fatigue design and FEM. Examination by handing in lab report.
BER1 - 1 extensive home assignment on fatigue design of a welded structure. Examination; handed in report.
BER2 - 1 extensive home assignment and case study on fatigue design of a welded structure. Examination; handed in 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 SD2420