MEEN40060 Fracture Mechanics

Academic Year 2022/2023

Syllabus: This module provides a comprehensive introduction to the important field of engineering fracture mechanics. Firstly, an overview is given of the historical development of the subject, from the early part of the twentieth century to the present day. Approximate equations are developed for the theoretical strength of a defect-free material using a simple atomic model. Linear elastic fracture mechanics (LEFM) is then introduced using both Griffith's energy-based and Irwin's stress intensity factor approaches.The experimental determination of a material's fracture toughness is then discussed with the aid of double cantilever beam (DCB) and tapered double cantilever beam (TDCB) specimen geometries. The state of stress in the vicinity of a crack tip under the three fundamental modes of loading is then discussed and the size and shape of the plastic zone ahead of a crack tip are determined. The influence of the three dimensional state of stress in the near-tip region on the apparent fracture toughness is also analyzed.Great emphasis is placed on the application of fracture mechanics as a engineering design and analysis tool, and numerous case studies are examined.The important application of LEFM to fatigue crack growth is discussed in detail, with comparison being made to traditional approaches to fatigue design. The fatigue failure of the Comet aircraft in the 1950s will be analyzed in detail. An introduction to elastic-plastic fracture mechanics (EPFM) is also provided, with a discussion of the two most important fracture parameters, the crack tip opening displacement (CTOD) and the J-integral. As before, the standard testing procedures for the experimental determination of these parameters are described and the theoretical and practical importance of these quantities is discussed.

Laboratory Experiments:Two laboratory exercises will be undertaken, as follows:

Lab 1: Failure analysis of a selection of fractured engineering components.

Lab 2: Determination of the adhesive fracture energy of a self adhesive tape.

All laboratories are carried out with reference to current School Health and Safety protocols. Students should follow these during all laboratory activities. Further information is available at https://intranet.ucd.ie/smme/index.html

Tutorials:Tutorials are integral part of the module and the students are strongly encouraged to attend all of the tutorial sessions.

Homework Assignment: An actual case study will be analyzed using the principles of fracture mechanics to gain insight into the failure of a critical machine component.

Textbook: Fracture Mechanics - Fundamentals and Applications, T.L. Anderson, 4th edition, CRC Press (Taylor & Francis), 2017.

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Curricular information is subject to change

Learning Outcomes:

On successful completion of this subject the student will be able to:

1. Establish the theoretical stress distributions ahead of a crack under brittle and ductile conditions.
2. Explain the relationship between linear elastic and non-linear fracture concepts and the terms K, G, CTOD and J.
3. Distinguish between the mechanisms of fracture under brittle and ductile conditions.
4. Appreciate how to make valid fracture toughness measurements for a range of materials.
5. Apply the principles of fracture mechanics to predict the fatigue life of engineering components.

Student Effort Hours: 
Student Effort Type Hours
Lectures

30
Tutorial

6
Laboratories

4
Autonomous Student Learning

70
Total

110
Approaches to Teaching and Learning:
Although largely a descriptive module, where the fundamental concepts and principles underlying the science of Fracture Mechanics are discussed in the lectures, there is also an emphasis on the application of the theory to solve numerical problems. This is most effectively achieved by considering a series of case studies which are solved in class using an informal tutorial style, where students are encouraged to think about and discuss the most appropriate approach to a given problem. The lecturer is very approachable and is always available to meet with students to discuss any topic for which they require further clarification. 
Requirements, Exclusions and Recommendations
Learning Recommendations:

Students should have MEEN30020 or equivalent.


Module Requisites and Incompatibles
Not applicable to this module.
 
Assessment Strategy  
Description Timing Open Book Exam Component Scale Must Pass Component % of Final Grade
Lab Report: Lab report to be submitted via Brightspace. Varies over the Trimester n/a Graded No

10
Assignment: Homework Assignment Week 7 n/a Graded No

15
Examination: Final Examination 2 hour End of Trimester Exam No Graded No

65
Lab Report: Lab report to be submitted via Brightspace: Failure Analysis Laboratory.
 Varies over the Trimester n/a Graded No

10

Carry forward of passed components
Yes
 
Resit In Terminal Exam
Spring Yes - 2 Hour
Please see Student Jargon Buster for more information about remediation types and timing. 
Feedback Strategy/Strategies

• Feedback individually to students, post-assessment
• Group/class feedback, post-assessment

How will my Feedback be Delivered?

Assignment: Individual feedback will be provided via Brightspace. Laboratory Reports: Will be submitted via Brightspace and a short individual feedback will be provided (also via Brightspace) by the teaching assistant in charge of the lab. Exam: Individual feedback will be provided on request after the grades have been released.

Fracture Mechanics: Fundamentals and Applications, T. L. Anderson. CRC Press.
Name Role
Dr Ehsan Rezvani Tutor
Timetabling information is displayed only for guidance purposes, relates to the current Academic Year only and is subject to change.
 
Autumn
      
Lecture Offering 1 Week(s) - 1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12 Mon 14:00 - 14:50
Lecture Offering 1 Week(s) - Autumn: All Weeks Thurs 10:00 - 10:50
Lecture Offering 1 Week(s) - Autumn: All Weeks Tues 10:00 - 10:50
Laboratory Offering 1 Week(s) - 2, 10 Fri 15:00 - 16:50
Laboratory Offering 2 Week(s) - 3, 9 Fri 15:00 - 16:50
Laboratory Offering 3 Week(s) - 4, 8 Fri 15:00 - 16:50
Laboratory Offering 4 Week(s) - 5, 11 Fri 15:00 - 16:50
Laboratory Offering 5 Week(s) - 6, 7 Fri 15:00 - 16:50
Laboratory Offering 6 Week(s) - 2, 10 Thurs 15:00 - 16:50
Laboratory Offering 7 Week(s) - 3, 9 Thurs 15:00 - 16:50
Laboratory Offering 8 Week(s) - 4, 8 Thurs 15:00 - 16:50
Laboratory Offering 9 Week(s) - 5, 11 Thurs 15:00 - 16:50
Laboratory Offering 10 Week(s) - 6, 7 Thurs 15:00 - 16:50
Autumn