Download JNTUA M.Tech 2nd Sem Supply 2018 Feb 9D15203 Mechanical Vibrations Question Paper

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Code: 9D15203

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M.Tech II Semester Supplementary Examinations February 2018

MECHANICAL VIBRATIONS

(Machine Design)

(For students admitted in 2012, 2013, 2014, 2015 & 2016 only)

Time: 3 hours Max. Marks: 60

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Answer any FIVE questions

All questions carry equal marks

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1. (a) Define transmissibility and derive an expression for the transmissibility ratio and the phase angle for transmitted force.
   (b) A machine of total mass 68 kg mounted on spring of stiffness k = 1100 kN/m with an assumed damping factor of 0.2. A piston within the machine has a mass of 2 kg has a reciprocating motion with stroke of 75 mm and speed of 3000 rev/min. Assuming the motion of piston to be SHM. Determine:
   1. (i) Amplitude of machine.

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   2. (ii) Phase angle with respect to exciting force.
   3. (iii) Transmissibility and force transmitted to foundation.
   4. (iv) Phase angle of transmitted force.
2. (a) Show that the response to a unit step function, designated by g(t), is related to impulsive response h(t) by the equation h(t) = g'(t).
   

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   (b) A force F(t) us suddenly applied to a mass m which is supported by a spring with a constant stiffness k N/m. After a short period of time T, the force is suddenly removed. During the time the force is active, it is constant, T. Determine the response of the system if t > T. The spring and mass are initially at rest before the force F(t) is applied.
3. (a) A vibrometer gives a reading relative displacement 0.5 mm. The natural frequency of vibration is 600 rev/min and the machine runs at 200 rev/min. Determine the magnitude of displacement, velocity and acceleration of the vibrating machine part.
   (b) Explain the working principle of seismic instrument when it measure displacement and acceleration.
4. (a) Determine the differential equation, natural frequency and the amplitude ratio of the system shown in figure below:
   

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