25-08-2017, 09:32 PM
SEMESTER EXAMINATIONS FOR MECHANICAL VIBRATIONS
MECHANICAL VIBRATIONS[.pdf (Size: 36.5 KB / Downloads: 35)
Answer any five questions
All questions carry equal marks
1. A mass of 12 kg is suspended from one end of a helical spring and the other end is fixed. The stiffness of the spring is 10 kN/m. The damping coefficient is 60 Ns/m. If a periodic force of 200Sin60t N is applied at the mass in the vertical direction, find the amplitude of the forced vibrations and its value at resonant condition.
2. A vibratory system of natural frequency 8Hz starts its motion with initial displacement of one cm and a velocity of 56 mm/sec. Determine the amplitude, phase of displacement, velocity and acceleration.
3. A radio set of 20 kg mass must be isolated from a machine vibrating with amplitude of 0.05mm at 500 rpm. The set is mounted on four isolators, each having a spring scale of 36kN/m and damping factor of 400 N-s/m. Calculate the dynamic load on each isolator due to vibration, amplitude of vibration.
4. Discuss the techniques used for spectrum analysis to understand the behavior of a machine.