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101-0121-00L 4 Credits DR , MSC D-MATL , D-BAUG , D-MAVT
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Fatigue and Fracture in Materials and Structures

Lecturers & Examiners: Prof. Dr. Andreas Taras, Dr. Elyas Ghafoori
VVZ CR n/a

Last Updated: 2026-02-05 15:36:27

Abstract

An introduction to fatigue and fracture in materials and structures will be given. The fundamentals of fatigue and fracture, which are useful in different engineering disciplines (e.g., for mechanical, aerospace, civil and material engineers) will be discussed. The focus will be on fundamental theories (based on fracture mechanics) that model cyclic loading, fatigue damage and crack propagation.

Objective

In this course, the students will learn: • Mechanisms of fatigue crack initiations in materials. • Linear elastic and elastic-plastic fracture mechanics. • Modern computer-based techniques (using ABAQUS Finite Element Package) to simulate cracks in both bulk materials and bonded joints/interfaces. • Laboratory fatigue and fracture tests on details with cracks.

Content

The fundamentals of fatigue and fracture in materials and structures are explained in this course. It discusses the importance of fatigue and fracture in different engineering disciplines such as mechanical, aerospace, civil and material engineering domains. The preliminary topics that are covered in this course are: I) Damages mechanisms and crack initiation under cyclic loadings: • Mechanisms of fatigue crack initiation in (ductile and brittle) metals. • Crack initiation under uni-axial high-cycle fatigue (HCF) loadings: Wöhler (S-N) curves, constant life diagram approach (mean-stress effects), rainflow analysis and Miner's damage rule. • Crack initiation under multi-axial HCF loadings: multi-axial fatigue mechanisms, critical plane approach (critical distance theory), equivalent stress approach, proportional and non-proportional loading. • Low-cycle fatigue (LCF): phenomena and descriptive models. II) Fracture mechanics: • Energy analysis, energy release rate and limits of linear elastic fracture mechanics (LEFM). • Weight function approach: stress intensity factors, crack opening displacement, mixed-mode fracture, etc. • Elastic-plastic fracture mechanics: Irwin and Dugdale models, plastic zone shapes, crack-tip opening displacement and J-integral. • Fatigue crack growth (FCG): FCG models, Paris' law, cyclic plastic zones, crack closure effects, fracture mechanisms and microscopic features. This also includes FE modeling of the FCG and laboratory tests (at Empa). III) Introduction to cohesive zone models (CZMs): • Advantages and disadvantages of CZMs compared to the traditional LEFM. • Different bond-slip models for the bonded joints/interfaces. • Simulations of crack propagation using CZMs. IV) Computer laboratory to simulate cracks and debonding problems: • Finite Element (FE) modeling of complex details with cracks. • Computer laboratory: FE training and exercises using (the student edition of) the ABAQUS FE Package. V) Introduction to design of civil structures against fatigue and fracture. VI) Introduction to fatigue and fracture in aerospace structures: • Design philosophy based on damage tolerance approach. • Fatigue of mechanically fastened joints and built-up structures (aircraft wing boxes). • Crack repair techniques. VII) Visits to the Empa (Swiss Federal Laboratories for Materials Science and Technology) in Dübendorf, and “Laboratory Competition”. The students will: • Visit different small-scale and large-scale fatigue testing equipment. • Get to know different ongoing fatigue- and fracture-related projects. • Witness and help to conduct a fatigue test on a steel plate with a pre-crack and a fracture test on an adhesively-bonded joint. • Compare the experimental results with their own calculations (from the fracture theories). • “Laboratory Competition” at Empa: the student(s) with the closest predictions will win the “Empa Laboratory Competition” and will be awarded by a small prize.

Resources

Lecture Notes

Lectures are based on the lecture slides and the handouts, which will be given to the students during the semester.

Literature

1. Schijve J. “Fatigue of Structures and Materials”, 2008: New York: Springer. 2. Anderson T.L. “Fracture Mechanics - Fundamentals and Applications”, 3rd Edition, Taylor & Francis Group, LLC. 2005. 3. Budynas R.G., Nisbett J.K. “Shigley's Mechanical Engineering Design”, 2008, New York: McGraw-Hill.

General Information

Language
English
Levels
DR , MSC
Frequency
Yearly recurring

Examination

Type
session examination
Mode
written 150 minutes
Aids
The exams will be "open book", therefore, all printed and hand-written materials are allowed. Furthermore, a calculator (without the capability of wireless/internet connectivity) is allowed
Interim examinations will be conducted twice during the semester (around Weeks 5 and 10). Homework assignment will be distributed every week and will be collected a week after.The interim examinations and homework are optional, and, in case, they would worsen the total grade, they are disregarded. They function as a bonus, but not as a penalty. Students can still achieve the maximum grade of 6 in the course unit even if they only sit the final examination.- Homework (10%)- First interim written examination (10%)- Second interim written examination (10%)

Course Components

Type Title Time & Place Hours
lecture with exercise Fatigue and Fracture in Materials and Structures
The lecturers will communicate the exact lesson times of ONLINE courses.
  • Tue 10:00-13:00 (ON LI NE)
3 h weekly

Offered In