Fatigue and Fracture Mechanics

Code:

EM0067

Acronym:

FMF

Keywords
Classification	Keyword
OFICIAL	Applied Mechanics

Instance: 2012/2013 - 1S

Active?	Yes
Responsible unit:	Applied Mechanics Section
Course/CS Responsible:	Master in Mechanical Engineering

Cycles of Study/Courses

Acronym	No. of Students	Study Plan	Curricular Years	Credits UCN	Credits ECTS	Contact hours	Total Time
MIEM	42	Syllabus since 2006/2007	5	-	6	56	160

Teaching language

Suitable for English-speaking students

Objectives

This course aims to acquaint students with concepts and techniques for the structural integrity assessment of mechanical constructions in the presence of cracks. The course is relevant for the design of equipment taking into account fatigue and for the  interpretation of the causes of structural failure (“failure analysis”). By the end of the semester, students should be capable of:

- selecting procedures to assess the structural integrity of mechanical components, structures, and structural connections with cracks;

- coordinating the analysis of the causes by fracture and fatigue in real cases;

- to understand the relevant technical literature, including standards, codes, and parts of standards and of codes associated with fracture and fatigue.

Learning outcomes and competences

- select procedures to and carry out the assessment of the structural integrity of mechanical components, structures, and structural connections with cracks;

- coordinate the analysis of the causes by fracture and fatigue in real cases;

- to understand the relevant technical literature, namely technical papers, standards, codes, and parts of standards and of codes associated with fracture and fatigue.

Working method

Presencial

Pre-requirements (prior knowledge) and co-requirements (common knowledge)

Knowledge and particular liking for the subjects: solid mechanics, theory of elasticity, and finite elements method.

Program

1. Linear elastic fracture mechanics; stress analysis of cracks; concept of stress intensity factor, K; energy methods; concept of strain energy release rate G; Relations between K and G; plastic region in crack tips; state of plane stress and plane strain; equivalent elastic crack;  plane strain fracture toughness  KIC; ASTM E339 standard; resistance R-curve and stable propagation of cracks; experimental toughness measurement; 2. Elasto-plastic fracture mechanics; Dugdale’s method; crack opening displacement COD - tests and standards; The Welding Institute (TWI) design curve; Relationship between J-integral and COD; 3. stable crack propagation: fatigue and stress corrosion cracking; Paris’ law; concept of threshold for crack propagation; relationship between SN tests (Wohler) and fracture mechanics tests; 4. Application of fracture mechanics to composite material; 5. Failure analysis; CEBG R6 procedure; 6. Computational fracture mechanics; calculation of J integral, strain energy release rate and stress intensity factor.

Mandatory literature

Knott, John; Fracture mechanics. ISBN: 0-901716-28-6
Ewalds, H. L.; Fracture mechanics
Anderson, T. L.; Fracture mechanics. ISBN: 0-8493-4277-5
Broek, David; Elementary engineering fracture mechanics. ISBN: 90-247-2656-5
Branco, Carlos Augusto Gomes de Moura; Fadiga de estruturas soldadas

Complementary Bibliography

Sanford, R. J. 340; Selected Papers on Foundations of Linear Elastic Fracture Mechanics. ISBN: 0-912053-55-0
Gdoutos, E. E.; Fracture mechanics criteria and applications. ISBN: 0-7923-0605-8
Sanford, R. J. 340; Selected Papers on Crack Tip Stress Fields. ISBN: 0-912053-56-9

Teaching methods and learning activities

Lectures; tutorials; combined lectures and tutorials; sessions in PC rooms; visit to lab. .

Software

Ansys 5.7

keywords

Technological sciences > Engineering > Aerospace engineering
Technological sciences > Technology > Industrial technology > Mechanical design
Technological sciences > Engineering > Mechanical engineering

Evaluation Type

Evaluation with final exam

Assessment Components

Description	Type	Time (hours)	Weight (%)	End date
	Exame		100,00
	Total:	-	100,00

Amount of time allocated to each course unit

Description	Type	Time (hours)	End date
	Frequência das aulas	50
	Estudo autónomo	110
	Total:	160,00

Eligibility for exams

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Calculation formula of final grade

The course final mark will be based on the final exam. The quality of the assignments and students’ assiduity may be taken into account.

Examinations or Special Assignments

Students will be encouraged to do assignments.

Internship work/project

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Special assessment (TE, DA, ...)

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Classification improvement

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Observations

This course can be taught in English if this is justified by a significant number of non-Portuguese speaking  students. However, course will be in English only if the Portuguese students do not oppose the use of a foreign language.