Training in Fatigue Analysis of Constructions

Course description

The course will concentrate on typical construction metals like steel or aluminium. The theoretical part of the course includes the background of fatigue cracks from the viewpoint of material science, the methods for a useful load analysis, the strength analysis using guidelines (‘FKM Guideline for Analytical Strength Assessment of Components in Mechanical Engineering’), the design of experiments and the estimation of remaining lifetime.
In the practical part of the course the participants will learn how to measure loads using the example of a bicycle, how to classify the loads and finally how to use the data to perform an analytical, numerical or experimental fatigue analysis. Experimental testing methods will be presented by small, portable test rigs (rotating bending test of a shaft, pneumatic test rig of a handlebar), and by a visit of the fatigue test field of the institute of machine elements, design and manufacturing.

 Course content

The training will be a balanced mixture of active periods with experiments and practical use-cases and passive periods where the lectures present the theory. The course will be subdivided in several thematic blocks. Each block will consist of a presentation of the theory, the methods and the workflow how to handle in practical applications. Furthermore, the participants will perform experiments, handmade analysis or learn how to handle a computer software to train the content of the block.

The following contents will be part of the course:

• Load analysis (data acquisition, counting methods, load collectives) using example of bicycle,
• Wöhler diagram (S-N curve),
• Influence of: material, mean stress, surface (roughness + hardness), notches, size of the component and multiaxial stress situations,
• Fatigue crack propagation, estimation of remaining lifetime,
• Analysis using ‘FKM Guideline for Analytical Strength Assessment of Components in Mechanical Engineering’,
• Testing methods (types of actuators, load collectives, real time signals),
• Fatigue analysis using finite element models,
• Condition monitoring by apps (e.g. SAFEME4MINE app) and practical examples (bolts, rims and welds),
• Best practice use cases (for example: design of bolt junctions, design of notches)

Timetable first day:

1. Material behavior
2. Load analysis
3. Analytical fatigue analysis
4. Specification of experiments
5. Optional: Barbeque and visit of the hydraulic and electromagnetic test rigs (evening event)

Timetable second day:

1. ‘FKM Guideline for Analytical Strength Assessment of Components in Mechanical Engineering’ and literature review
2. Numerical methods like the finite element method
3. Estimation of remaining lifetime
4. Condition monitoring and best practice examples.

Objectives and outcomes

• The alumni of the course are able to identify components and locations with a high risk for fatigue cracks.
• The participants are able to develop a plan to analyse the fatigue behaviour by tests or calculation methods after joining this course.
• The alumni of the course can distinguish between material, design, manufacturing and operational based parameters.
• The participants are qualified to find solutions for fatigue problems by modifying the material or design.
• The attendees of the course are able to gather material stresses from external loads.
• The participants are able to estimate the residual life of a cracked component.
• After the course the participants can distinguish between fatigue and wear.
• The alumni of the course can create specifications for a fatigue analysis done by testing companies.