2019 Strength and Fracture of Materials (Mechanical Engineering)

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Academic unit or major
Undergraduate major in Mechanical Engineering
Sato Chiaki  Todoroki Akira  Mizutani Yoshihiro  Kurokawa Yu  Suzuki Yoshiro 
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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.


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 Failure of materials Understand the types and characteristics of materials.
Class 3 Energy release rates Understand fracture mechanics in terms of energy balance and the Griffith's theory.
Class 4 The stress field and stress intensity factor near a crack tip Understand the theory of elasticity of crack tip
Class 5 Stress intensity factor Understating of stress intensity factors.
Class 6 Examples of stress intensity factors and principle of superposition Understand the examples of stress intensity factors and principle of superposition.
Class 7 Relationship between energy release rate and stress intensity factor Understand the principle of stress intensity factor though energy balance theory .
Class 8 Plastic deformation at the crack tip Understand the plastic deformation at the crack tip.
Class 9 Crack tip opening displacement and fracture toughness Understand the crack opening displacement fracture toughness.
Class 10 Stable crack growth, R-Curve, Plain strain fracture toughness, Fracture appearance transition temperature, Dynamic fracture Understanding of Stable crack growth, R-Curve, Plain strain fracture toughness, Fracture appearance transition temperature, Dynamic fracture
Class 11 The mechanism of fatigue crack initiation and propagation; time dependent fracture Understand crack initiation, velocity, threshold, the mechanism of crack propagation crack ; time dependent fracture opening displacements for fatigue cracks
Class 12 Design of fracture control Understanding of the basic theory of fracture control and feasibility studies
Class 13 Non-destructive inspection Introduction and understanding of non-destructive inspection.
Class 14 Exercise
Class 15 Examination and answers


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

Reference books, course materials, etc.

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

Assessment criteria and methods

Exercise (10%) and final exam (90%).

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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