Exam in Deformation and Fracture

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Sáng nay mới thi xong, post đề lên cho anh em tham khảo cách ra đề và chấm điểm bên này.

Course: Deformation and fracture
Credits: 7.5
Literature: Deformation and Fracture Mechanics, Richard Hertzberg, John Wiley & Son, 1995, 786p.

Thang điểm:



Đề thi gồm 8 câu: mỗi câu đúng trọn vẹn được 3 điểm, chưa trọn vẹn được 2 điểm, chấp nhận được là 1 điểm.

Thời gian làm bài: 4h. Không được dùng tài liệu

1, Describe the difference between dislocation climb and cross slip. What is controlling if the two mechanisms happen?

2, Describe the phenomenon called twinning and why it is more frequently encountered in for example Ti-alloys than steels.

3, Disperson and precipitation strengthening mechanisms. Describe how these mechanisms operate and how they are influenced by time and temperature.

4, What mechanisms will cause failure during a creep test?

5, Stress intensity factor K and fracture toughness Kc are parameters derived based on completely brittle materials such as glass. Can they be used for less brittle materals such as metals and if that is the case, why?

6, Why will cracks in a steel start growing when put under a load and exposed to humidified argon gas and stop when the environment is changed to humidified plus oxygen?

7, What does a Wöhler-curve describe and how does differ between steel and aluminum? What can you do to the material and/or your component to improve the fatigue life?

8, Explain the concept of a "cyclic stress-strain curve". Can you read from this diagram if the material undergoes cyclic hardening ?

The end.