Download JNTU (OR) M.TECH 1-Semester CREEP FATIGUE AND FRACTURE MECHANICS January / February-2007 Exam Question Paper

Code No: 13/MDN
OR
M.Tech. I-Semester Examinations, January/February-2007.
CREEP FATIGUE AND FRACTURE MECHANICS
(Machine Design)
Time: 3 hours        Max. Marks: 60

Answer any FIVE questions
All questions carry equal marks

– – –
1.a)  What advantage does the fracture mechanics approach afford the
engineer in designing components compared to tranditional
approaches.
b)  Write a short notes on fracture at elevated temperatures.

2.a)  With the help of a stress – strain diagram, discuss the ‘Strain –
Hardening’ in a poly crystalline material. Enumerate the reasons
for strain hardening.
b)  Explain the construction of Mohr’s circle in 2D state of stress.

3.a)  Compare Von Mises and Tresca criteria. Mention various
advantages and disadvantages associated with each criterion.
b)  Write short notes on different modes of crack opening.

4.a)  Explain how the effect of small notches or cracks can be analysed
in terms of fracture toughness.
b)  Explain various experimental methods for measuring Kic.

5.a)  Sketch and explain the cumulative damage theory to explain
fatigue failure.
b)  Explain stage I, stage II and stage III of fatigue crack growth.

6.  Explain the following:
a)  High cycle fatigue
b)  Fatigue crack closure theories
c)  Factors affecting the fatigue likes of welded joints
d)  MINER’s law.

7.  Discuss in detail the following:
a)  Creep resistant materials
b)  Multi axial creep
c)  Creep – fatigue interaction.

8.  Write short notes on the following:
a)  Coffin – Marson law.
b)  Three principle ways in which fatigue stresses develop.
c)  Ductile – Brittle transition temperature.
d)  good man mean stress corrections

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