Module: Introduction to Fatigue and Fracture Mechanics

Objectives

Over time, materials undergo aging processes akin to those experienced by humans, gradually evolving and showing signs of fatigue and wear. It is therefore important to understand the reason and source of aging in materials in order to build models that can be used for design of structures.
The module aims at discussing the importance of aging of materials, in particular metals, in different engineering disciplines such as civil and structural engineering (e.g., pipelines, studioms, silos, bridges, offshore and onshore wind turbines), mechanical engineering (e.g., pressure vessles, automotive and ship industries) and aerospace engineering (e.g., aircraft industry). It provides different engineering tools to simulate fatigue damage in steel and also model the behaviour and effect of a crack in steel members.
At the end of the module, the students will be familiar with different types of nominal and local approaches and are aware of their areas of applications as well as their limitations. After successful completion of the module, the students will have the skills for choosing the most appropriate fatigue and fracture criteria depending on the problem for efficient and realistic simulations.

Topics

The Module has two main parts.
The first part gives an overview on different approaches in fatigue assessment and includes:

• Mechanisms of fatigue crack initiation in (ductile and brittle) metals such as steels
• Crack initiation under uni-axial high-cycle fatigue (HCF) loadings
• Crack initiation under multi-axial HCF loadings

The second part of the course is dedicated to the theory of fracture mechanics:

• Linear elastic fracture mechanics (LEFM)
• Elastic-plastic fracture mechanics
• Fatigue crack growth (FCG) models
• Cohesive zone models (CZMs)

Computer laboratory: the students will get to know the modern computer tools for assessment of cracks in complex details using computer models such as finite element (FE) simulation techniques.
Laboratory visit: the students will visit the testing laboratory of the Institute for Steel Construction to witness different running experiments will be arranged.

Exam