Download JNTUA M.Tech 1st Sem 2018 Aug-Sept 9D15106a Tribology Question Paper

Download JNTUA (JNTU Anantapur) M.Tech ( Master of Technology) 1st Semester 2018 Aug-Sept 9D15106a Tribology Previous Question Paper

Code: 9D15106a


M.Tech I Semester Supplementary Examinations August/September 2018
TRIBOLOGY
(Machine Design)
(For students admitted in 2013, 2014, 2015 & 2016 only)

Time: 3 hours Max. Marks: 60

Answer any FIVE questions
All questions carry equal marks
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1 (a) What are skewness and kurtosis of rough surfaces? Explain with schematic sketches.
(b) What are auto covariance and autocorrelation functions?

2 (a) Outline the considerations that govern the following aspects of the performance of rolling-element
bearings: (i) Load capacity. (ii) Rotational speed. (iii) Life. (iv) Lubrication requirements.
(b) A shaft rotating at constant speed is subjected to variable load. The bearings supporting the shaft
are subjected to stationary equivalent radial load of 3 kN for 10 per cent of time, 2 kN for
20 percent of time, 1 kN for 30 per cent of time and no load for remaining time of cycle. If the total
life expected for the bearing is 20 x 10
6
revolutions at 95 percent reliability, calculate dynamic load
rating of the ball bearing.

3 (a) Derive the one dimensional Reynolds equation for long bearing approximation.
(b) Derive the bearing parameters from the general Reynolds equation.

4 (a) Derive the relation for lubricant flow of flat circular hydrostatic pad bearing.
(b) What are aerostatic bearings? List its advantages.

5 (a) What do you understand by sintered bearings? What are its applications?
(b) What are the advantages of PTFE bearings? What do you understand by self-lubricated bearings?

6 (a) Differentiate between lubricant and lubrication. Explain how MoS
2
act as good solid lubricant.
(b) What are additives? How it contributes in lubrication?

7 (a) List the different types of seals and its applications.
(b) Discuss the importance of Seal face materials and their significant properties.

8 (a) Tabulate service failures and its causes of bearings.
(b) List the common contaminants and its possible sources.

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