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Total No. of Questions: 8]
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Roll No ........................................
MMMD-301(A)
M.E./M.Tech., III Semester
Examination, November 2023
Fatigue Fracture Analysis
(Elective-I)
Time: Three Hours
Maximum Marks : 70
Note: i) Attempt any five questions.
ii) All questions carry equal marks.
1.
a)
What are the various factors influencing fatigue behavior?
b)
Analyze the effect of compressive cyclic stress on fatigue.
2.
a)
Differentiate between low cycle fatigue and high cycle fatigue.
b)
Describe briefly Gerber, Goodman and Soderberg's criteria with a neat sketch.
3.
a)
Show the S-N diagram with natural and log-log scales. Indicate the values of Fatigue strength and Fatigue life on these curves.
b)
Explain the information about the materials from the fatigue fracture Surfaces.
4.
a)
What is the difference between failure of a material by creep and that by stress rupture?
b)
What type of specimen specifications and test types are employed when testing creep properties of flat plate type samples?
5.
a)
What is creep behavior? Explain with sketch the different stages of creep.
b)
What is meant by creep relaxation? With a neat sketch, explain briefly about primary creep, secondary creep and tertiary creep.
6.
Using Griffith Equation, determine the critical crack length for steel for the following: σcritical = 1150 MPa, Y = surface energy per unit area= 1.5 J/m², E= 200 GPa, What would be the critical crack length according to the Griffith-Orowan equation? Take p = plastic work required to extend the crack wall = 1200 J/m².
7.
a)
With the help of a neat sketch explain the process of crack initiation and explain the stages of crack initiation.
b)
Write about the fracture process and analysis in metals.
8.
a)
Endurance limit
b)
Stress concentration and stress concentration factor
c)
Creep resistant materials
d)
Plane stress fracture toughness