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2017　Strength and Fracture of Materials (Mechanical Engineering)

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Academic unit or major
Undergraduate major in Mechanical Engineering
Instructor(s)
Nakamura Haruo  Sato Chiaki 
Class Format
Lecture     
Media-enhanced courses
Day/Period(Room No.)
Fri1-4(I121)  
Group
-
Course number
MEC.C331
Credits
2
Academic year
2017
Offered quarter
2Q
Syllabus updated
2017/5/30
Lecture notes updated
-
Language used
Japanese
Access Index

Course description and aims

Based on the fundamentals of mechanics learned in Mechanics of Materials and Elastoplastic Mechanics, the instructor will first introduce various failure examples and failure laws, then lecture on the fundamentals of linear fracture mechanics and elastoplastic fracture mechanics. Next, the instructor will touch on several forms of fracture seen in materials, and lecture on fracture toughness and fatigue strength, generation and growth mechanisms of fracture cracks. Finally, the instructor will lecture on the fundamentals and techniques of strength design for leveraging this knowledge for actual design, maintenance, and management.
An understanding of deformation and fracture that occur when force is applied to a structural material is necessary for designing machines and structures, as well as maintaining and managing them. Students in this course will gain an understanding of the mechanics of material fracture and failure, fracture toughness and fatigue strength, the fundamentals of generation and growth mechanisms of fatigue cracks, and the microscopic phenomena of materials, as well as learning how macroscopic material deformation and fracture is related to microscopic phenomena. In addition, students will learn methods of considering strength design methods that leverage this knowledge for the actual design, maintenance, and management of machines and structures.

Student learning outcomes

By the end of this course, students will be able to:
1) Understand deeply the failure and fracture of materials, and related mechanics.
2) Understand the fundamentals on the basic characteristics of material strength, fatigue life, and strength design.
3) Carried out strength design of machinery or structures.
4) Identify problems when maintenance troubles occur.

Keywords

Fracture, Crack, Fatigue, Stress intensity factor, Fracture toughness, Critical fracture energy, J-integral,

Competencies that will be developed

✔ Specialist skills Intercultural skills Communication skills Critical thinking skills ✔ Practical and/or problem-solving skills

Class flow

In the first half students will gain an understanding of basic properties of material strength, as well as the fundamentals of fracture mechanics. In the second half they will learn about applications. Homework will be assigned in some classes for students to deepen their understanding. Please carefully read the learning goals for each class, and prepare and review diligently.

Course schedule/Required learning

  Course schedule Required learning
Class 1 History of accidents caused by the fracture of materials and the role of this course Understand the historical aspects on and percept from accidents caused by fracture of materials.
Class 2 Laws of stress, strain, and failure Understand the types and characteristics of failure criteria.
Class 3 The stress field and stress intensity factor near a crack tip Understand the necessity of fracture mechanics when a crack exists in material.
Class 4 Energy release rates Understand fracture mechanics in terms of energy balance and the Griffith's theory.
Class 5 A plastic zone in the vicinity of a crack tip Understand the modification of fracture mechanics for small scale yielding.
Class 6 The J integral and crack opening displacement Understand the various criteria for elastoplastic fracture mechanics.
Class 7 Ductile fracture and brittle fracture Understand the dependency of fracture type on material characteristics.
Class 8 Fracture toughness Understand the relation between KIC and GIC
Class 9 Fatigue fracture ( fatigue limit on a S-N curve) Understand the fatigue life of a material shown by a S-N curve.
Class 10 The influence of various factors on the fatigue life of a material Understand the influence of stress amplitude, stress ratio, ,frequency, and notch or flaws in a structure on the fatigue life.
Class 11 The mechanism of fatigue crack initiation, small cracks and low cycle fatigue Understand crack initiation, the influence of stress deviation, and the evaluation method of low cycle fatigue.
Class 12 The mechanism of fatigue crack propagation Understand crack velocity, threshold, the mechanism of crack propagation, crack opening displacements for fatigue cracks
Class 13 Fundamentals of strength design (safety and reliability) Understand design philosophy to ensure safety and reliability.
Class 14 Various methods for strength design (safe-life or fail-safe design) Understand design rules and inspection methods to avoid the initiation and propagation of fatigue crack.
Class 15 Exercise

Textbook(s)

Strength and Fracture of Materials （ISBN 4-901381-26-1）, The Society of Materials Science, Japan.

Reference books, course materials, etc.

Hideo Kobayashi, Fracture Mechanics (ISBN 978-4-320-08100-0), Kyoritsu Shuppan Co., Ltd.

Assessment criteria and methods

Homework (20%), Midterm exam (20%), and final exam (50%).

Related courses

  • Mechanics of materials
  • Elastoplastic mechanics

Prerequisites (i.e., required knowledge, skills, courses, etc.)

It is preferable that all the students have enough knowledge on mechanics of materials and elastoplastic mechanics.

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