Metal fatigue a significant problem
The failure of structures caused by fatigue is a well-known technical phenomenon. Since the rising early 19th century of the first rotating machinery – subject to cyclic loads by nature – numerous fatal accidents due to metal fatigue have been reported. In the early days, important research has been done by August Wöhler. He discovered that applying a single load far below the static strength of the structure, did not damage the structure. However, when the same load was applied repeatedly, it could lead to fatal failure of the structure.
More recently, it became clear that applying repetitive, alternating loads to a structure could initiate a fatigue mechanism in the material, leading to the initiation of micro-cracks, followed by crack growth and eventually to a complete fatigue fracture.
During the recent history, numerous fatal accidents happened due to metal fatigue with ground vehicles, airplanes, welded structures, pressure vessels, etc. Nonetheless, many fatigue problems are not systematically reported, but the economic impact of non-fatal fatigue failure is considerable and cannot be underestimated.
Structural fatigue is now generally recognised as a significant problem. Performing a fatigue analysis however, is not a simple task. A strong theoretical knowledge is essential to predict and evaluate metal fatigue with Finite Element Analysis successfully.
What will you learn during this Fatigue Analysis training?
In this course great attention is paid to the theoretical background of the mechanisms leading to fatigue and to the modern methods used to analyse fatigue problems. The use of tools like Finite Element Analysis for the evaluation of fatigue is extensively discussed, but also other, perhaps more accessible tools like Excel or Python.
The goal of this course is to provide an overview of the physical principles causing metal fatigue, to show how to break down the fatigue analysis process in clearly defined steps and to learn how to use hand calculations and Finite Element Analysis to successfully analyse practical fatigue applications.
Who should attend the course?
This course aims at designers and engineers involved in the evaluation of the durability and fatigue life of structures. The course material presented is completely software-independent and is therefore accessible for all current or future users of any available commercial FEA or dedicated fatigue analysis software.
This course is a must for all designers and engineers who wish to obtain a broader knowledge in the assessment and analysis of the fatigue life of structures and gain a greater insight in how to improve the durability of structures and components.
A minimal knowledge of the basics of strength of materials is expected from the students. A basic practical knowledge of the use of Finite Element Analysis is ideal, but not imperative.
Content of the course
- Introduction to fatigue as a failure mechanism
- Definition of fatigue
- Micro- and macroscopic material behaviour
- Historical and modern fatigue analysis practice
- Overview of fatigue analysis methods
- General methods for durability assessment
- Effect of mean stress
- Fatigue correction factors
- High-cycle fatigue (S-N or Stress-Life approach)
- Concepts of high-cycle fatigue and fatigue strength
- Material fatigue properties for high-cycle fatigue
- Palmgren-Miner’s rule for damage accumulation
- Low-cycle fatigue (E-N or Strain-Life approach)
- Concepts of low-cycle fatigue
- Stress concentrations
- Material fatigue properties for low-cycle fatigue
- Local plasticity and notch corrections according to Neuber
- Multi-axial loading
- Fatigue of welded structures
- Methods to predict the fatigue life of welded structures
- Introduction to fracture mechanics
- Linear Elastic Fracture Mechanics (LEFM)
- Evaluation of structures with pre-existing cracks
- Analysis of fast crack growth and fracture