Sardar Vallabhbhai National Institute of Technology 2012 B.Tech Mechanical Engineering Tribology and machine dynamics - Question Paper
SARDAR VALLABHBHAI NATIONAL INSTITUTE OF TECHNOLOGY, SURAT MECHANICAL ENGINEERING DEPARTMENT END SEM EXAMINATION - MAY 2012 SUB: TRIBOLOGY AND MACHINE DYNAMICS 08:30-10:30 Date: 03/05/12
Time: 2 hr. Marks: 50
(1) Attempt all the questions
(2) Figure to the right indicates full marks
(3) Use appropriate tools for sketch or drawing
Q. 1 Answer any three (12)
1. Draw with pencil the schematic diagrams showing the structure of metallic surface with nomenclature.
Enlist Reynolds equation assumptions with comments in tabular form.
3. What are SAE grades of oils? Give example of mono/multigrade oil with its explanation.
4. Write Reynolds equations of 2D with nomenclature. Explain the term dp/dx,dp/dy and dh/dx.
5iExplain the effect of temperature on viscosity with suitable sketch/ graph and example.
Q.2
Answer the following
Derive the equation of Abrasive friction. Draw sketch with list of assumptions.
Jx A typical profilometer trace show an uniform triangular surface (05) asperities having 0.05 mm height and 0.25 mm pitch. If the sample length is taken 2 mm then determine the C.L.A., R.M.S., asperity slope and plot the bearing area curve.
c. Write short note (any-one)
Jt' Type of wear
2. Tribological solutions
3. Lubrication regimes
Q-3 Answer the following (any two) . (10)
0
s
Derive the response equation for under damped spring, mass, damping system and Prove that it is periodic response.
2rExplain the term force transmissibility with suitable diagram, graphs and equations.
3. Derive equation for Magnification Factor using vector method and show graph of MF vs. frequency ratio r.
Q. 4 Answer the following.
-rDetermine the natural frequency of the spring mass pulley system shown (04) in Fig.l
Jjr' Fig.2 shows a simple model of a motor vehicle that can vibrate in vertical direction while travelling over a rough road, the vehicle has a mass of 1200 kg. the suspension system has a spring constant of 400 kN/m and a damping ratio of =0.5. If the vehicle speed is 20 km/hr, determine the displacement amplitude of the vehicle, the road surface varies sinusoidally with the amplitude of the vehicle. The road surface varies sinusoidally with an amplitude of Y= 0.05 and a wavelength of 6 m.
c. A machine weight 18 kg and is supported on springs and dashpots. The (05) total stiffness of the spring is 12 N/mm and damping is 0.2 N/mm/s. The system is initially at rest and a velocity of 120 mm/s is imparted to the mass, determine:
4
he displacement and velocity of mass as a function of time,
(ii/ the displacement and velocity after 0.4 s.
|
Xtt) |
 |
|
Fig.2 |
\
Fig.l
=x=x=x-x=x=x=
i
|
Attachment: |
| Earning: Approval pending. |
