Fatigue Analysis

Advanced treatment of low cycle and high cycle fatigue. Mechanisms involved in initiation and growth of fatigue cracks. Effects of corrosion and temperature. Material and mean strain effects. Effect of surface condition fabrication effects and surface modification to increase fatigue strength. Strain controlled fatigue, cyclic plasticity and notch effects. Fracture mechanics and fatigue: Crack growth modelling, short crack behaviour, threshold effects. Probabalistic design. Design criteria for multiaxial fatigue. Variable amplitude loading, linear og non-linear damage accumulation. Implementation of theory in design codes.

The course is aimed at providing an understanding of methodologies for fatigue life assessment of mechanical components and welded structures. An introduction is given to causes of fatigue and brittle failures and mechanisms and parameters that control the development and growth of cracks. A review over traditional assessment methods based on nominal stresses and strains is given. Recent methods based on finite element analysis (FEA), such as hot-spot, notch-stress/strain and fracture mechanics for welded structures are given special consideration. The course has the following learning objectives:Knowledge:Upon the completion, the candidate should have the knowledge of:- Causes of fatigue and brittle fractures in steel, aluminium, titanium and composite materials- Traditional methods for fatigue assessment and design against ductile and brittle fracture in welded structures and mechanical components- FEA based methods for designing against fatigue and fractureProficiency / Skills:Upon the completion, the candidate is able to:- Establish design models and procedures based on FEA codes such as Ansys and Abaqus for fatigue design and establish safety criteria and inspection intervals for structures experiencing slow crack growth- Design and conduct laboratory experiments for the verification of fatigue and fracture properties of components and structures- Understand and apply standards such as Eurocode 3, Eurocode 9 and British Standard BS 7910, and guidance such as DNV RP C-203 Fatigue design of offshore structures, plus equivalent guidance from IIW – International Institute of WeldingGeneral competence / Expertise:Upon the completion, the candidate is able to:- Evaluate the need for fatigue analyses as the basis for structural design and choose an effective analysis methododology- Understand and make use of the latest scientific research in computational methods in fatigue design

Lectures and group work.Literature survey of assigned topic with a written report. The lectures and exercises are in English when students who do not speak Norwegian take the course. If the teaching is given in English the Examination papers will be given in English only. Students are free to choose Norwegian or English for written assessments. To pass the course a score of at least 70 percent is required.