Roll No. Total No. of Pages : 02
Total No. of Questions: 18
B.Tech. (Mechanical Engineering) (Sem.-7)
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MECHANICAL VIBRATIONS
Subject Code: BTME-803
M.Code : 71996
Time : 3 Hrs. Max. Marks : 60
INSTRUCTIONS TO CANDIDATES :
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- SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks each.
- SECTION-B contains FIVE questions carrying FIVE marks each and students have to attempt any FOUR questions.
- SECTION-C contains THREE questions carrying TEN marks each and students have to attempt any TWO questions.
SECTION-A
Write briefly :
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- Differentiate Oscillation and Vibration.
- In short define types of Vibrations.
- Describe causes of vibrations.
- Vibration is a necessary Evil. Explain.
- What are various effects of vibrations? Explain.
- What do you understand by Natural frequency?
- With help of Figure explain multi-degree freedom system.
- What do you understand by degrees of freedom?
- Why soldiers are asked to break their steps while crossing a bridge? Explain.
- What is the principle of vibration absorber? Explain with help of neat sketch.
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SECTION-B
- A spring mass system with mass m kg and stiffness k N/m has a natural frequency of 1 Hz. Determine the value of stiffness kl of another spring which when arranged in conjunction with spring of stiffness k in series will lower the natural frequency by 20% and in parallel will raise the natural frequency by 20%.
- Describe and differentiate Coulomb and Viscous Damping in detail.
- Add two harmonic motions analytically which are represented by the equations :
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x(2) = 5 cos(7t-p/12)
Compare the result with graphical representation. - Torque T is applied at the midpoint of a uniform cross-section circular shaft of length 'I', which twists the shaft by angle a radians. If the torque is released suddenly, derive equation for resulting motion.
- Describe torsional vibration absorber with neat sketch.
SECTION-C
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- Explain the following :
- Vibration isolation transmissibility
- Torsional vibration of circular shafts
- A beam having length of 0.42 m, moment of inertia 10000m4 and modulus of elasticity 196000 N/m2 is supporting two masses 40 kg and 20 kg at a distance of 0.16 and 0.24 m from one end. Determine lowest natural frequency by Rayleigh's method.
- Determine the normal function for the boundary conditions as one end fixed and the other end free of a cantilever system of length 'I', starting with the expression for strain energy during free longitudinal vibration of bar with uniform area of cross-section.
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NOTE: Disclosure of Identity by writing Mobile No. or Making of passing request on any page of Answer Sheet will lead to UMC against the Student.
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