Download PTU (I.K. Gujral Punjab Technical University Jalandhar (IKGPTU) ) BE/BTech ME (Mechanical Engineering) 2020 March 7th and 8th Sem 59077 Mechanical Vibrations Previous Question Paper
Roll No. Total No. of Pages : 03
Total No. of Questions : 09
B.Tech. (ME) (Sem.?7)
MECHANICAL VIBRATIONS
Subject Code : ME-408
M.Code : 59077
Time : 3 Hrs. Max. Marks : 60
INSTRUCTIONS TO CANDIDATES :
1. SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks
each.
2. SECTION-B contains FIVE questions carrying FIVE marks each and students
have to attempt any FOUR questions.
3. SECTION-C contains THREE questions carrying TEN marks each and students
have to attempt any TWO questions.
SECTION-A
1. Write briefly :
a) Compare longitudinal vibrations and transverse vibrations with the help of diagrams.
b) Differentiate between Coulomb damping and Viscous damping.
c) What is the equivalent stiffness of spring connected in parallel having stiffness k1 and
k2.
d) Why viscous damping is preferred for analyzing vibration system?
e) Define static and dynamic coupling.
f) What is the difference between a discrete and continuous system? Is it possible to
solve any vibration problem as a discrete one?
g) What is Rayleigh?s energy method, Explain?
h) The natural frequency of spring mass system is 10Hz. When the spring stiffness is
reduced by 800 N/m the frequency is altered by 50%. Find the mass and stiffness of
the original system.
i) Define Eigen vector.
j) Define periodic motion and phase difference.
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1 | M-59077 (S2)-2775
Roll No. Total No. of Pages : 03
Total No. of Questions : 09
B.Tech. (ME) (Sem.?7)
MECHANICAL VIBRATIONS
Subject Code : ME-408
M.Code : 59077
Time : 3 Hrs. Max. Marks : 60
INSTRUCTIONS TO CANDIDATES :
1. SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks
each.
2. SECTION-B contains FIVE questions carrying FIVE marks each and students
have to attempt any FOUR questions.
3. SECTION-C contains THREE questions carrying TEN marks each and students
have to attempt any TWO questions.
SECTION-A
1. Write briefly :
a) Compare longitudinal vibrations and transverse vibrations with the help of diagrams.
b) Differentiate between Coulomb damping and Viscous damping.
c) What is the equivalent stiffness of spring connected in parallel having stiffness k1 and
k2.
d) Why viscous damping is preferred for analyzing vibration system?
e) Define static and dynamic coupling.
f) What is the difference between a discrete and continuous system? Is it possible to
solve any vibration problem as a discrete one?
g) What is Rayleigh?s energy method, Explain?
h) The natural frequency of spring mass system is 10Hz. When the spring stiffness is
reduced by 800 N/m the frequency is altered by 50%. Find the mass and stiffness of
the original system.
i) Define Eigen vector.
j) Define periodic motion and phase difference.
2 | M-59077 (S2)-2775
SECTION-B
2. Split x (t) = 5 sin ( ? t = 30?) into two harmonic motions one with 60? phase lead and
other with 45? phase lag.
3. Explain the whirling of shaft.
4. In a spring mass system, the mass of 10 kg makes 40 oscillations in 20 seconds without
damper. With damper, the amplitude decreases to 0.20 of the original value after 5
oscillations. Find out :
a) Stiffness of the spring
b) Logarithmic decrement
c) Damping factor.
5. A 5kg mass is placed at the end of a 30 cm steel beam as shown in Fig. Q5. When excited
by a harmonic excitation of magnitude 150 N, a vibration amplitude of 0.5mm is
observed. Determine the frequency of excitation.
Fig.1
6. Determine the natural frequency of the system shown in Fig. Q6.
Fig.2
150 sin t ?
5kg
30cm
m
a
l
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1 | M-59077 (S2)-2775
Roll No. Total No. of Pages : 03
Total No. of Questions : 09
B.Tech. (ME) (Sem.?7)
MECHANICAL VIBRATIONS
Subject Code : ME-408
M.Code : 59077
Time : 3 Hrs. Max. Marks : 60
INSTRUCTIONS TO CANDIDATES :
1. SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks
each.
2. SECTION-B contains FIVE questions carrying FIVE marks each and students
have to attempt any FOUR questions.
3. SECTION-C contains THREE questions carrying TEN marks each and students
have to attempt any TWO questions.
SECTION-A
1. Write briefly :
a) Compare longitudinal vibrations and transverse vibrations with the help of diagrams.
b) Differentiate between Coulomb damping and Viscous damping.
c) What is the equivalent stiffness of spring connected in parallel having stiffness k1 and
k2.
d) Why viscous damping is preferred for analyzing vibration system?
e) Define static and dynamic coupling.
f) What is the difference between a discrete and continuous system? Is it possible to
solve any vibration problem as a discrete one?
g) What is Rayleigh?s energy method, Explain?
h) The natural frequency of spring mass system is 10Hz. When the spring stiffness is
reduced by 800 N/m the frequency is altered by 50%. Find the mass and stiffness of
the original system.
i) Define Eigen vector.
j) Define periodic motion and phase difference.
2 | M-59077 (S2)-2775
SECTION-B
2. Split x (t) = 5 sin ( ? t = 30?) into two harmonic motions one with 60? phase lead and
other with 45? phase lag.
3. Explain the whirling of shaft.
4. In a spring mass system, the mass of 10 kg makes 40 oscillations in 20 seconds without
damper. With damper, the amplitude decreases to 0.20 of the original value after 5
oscillations. Find out :
a) Stiffness of the spring
b) Logarithmic decrement
c) Damping factor.
5. A 5kg mass is placed at the end of a 30 cm steel beam as shown in Fig. Q5. When excited
by a harmonic excitation of magnitude 150 N, a vibration amplitude of 0.5mm is
observed. Determine the frequency of excitation.
Fig.1
6. Determine the natural frequency of the system shown in Fig. Q6.
Fig.2
150 sin t ?
5kg
30cm
m
a
l
3 | M-59077 (S2)-2775
SECTION-C
7. Derive the frequency equation of torsional vibrations for a free-free shaft of length l.
8. A single degree of freedom viscously damped system has a spring stiffness of 600N/m,
critical damping constant of 0.3 N-s/mm. and a damping ratio of 0.3, if the system is
given an initial velocity of 1 m/s, determine the maximum displacement of the system.
9. Mention the conditions of Euler?s beam. Derive Eulers?s equation of motion for beam
vibration. Determine the natural frequencies and mode shapes for simply supported end
conditions.
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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This post was last modified on 21 March 2020