SET-1

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD R05 IV B.Tech. I Semester Supplementary, May/June – 2009

VEHICLE DYNAMICS (Automobile Engineering) Max. Marks.80 Answer any Five questions All questions carry equal marks

---

.in

Time: 3 hours

A flywheel having mass of 35 kg was allowed to swing as pendulum about knife edge at inner side of the rim,as shown in fig. If the measured period of oscillation was 1.22 seconds, determine moment of inertia of the flywheel about its geometric axis. [16]

2.

Briefly explain the various methods of damping in mechanical systems.

3.

A horizontal spring mass system subjected to dry fiction dempsis has the following physics data. Mass = 8.7 kg spring constant of the spring = 7550 N/m coefficient of friction between mass and the horizontal plane on which it slides =0.22. the is Subjected to a sinusoidal forcing friction of amplitude 19.6 N and frequency 5Hz. Find the amplitude of vibration of the mass and also calculated the equivalent viscous damping. [16]

4.

What is vibration? How do you measure it and explain any one instrument working principle in detailed? [16]

5.

For a tour spring having tension T and the two equal concentrated masses equidistant from supports, find the natural frequencies and mode shapes. [16]

or ld

1.

Aj

nt

uW

[16]

6.

A machine runs at 5000rpm. Its forcing fr3equency is very near to its natural frequency if the nearest frequency of the machine is to be at least 20% from the force3d frequency, design a suitable vibration absorber for the system .Assume the mass of the machine as 30kg. [16] Contd…2

Set-1 Draw cross section of an automobile tyre and show on its various constructional features. [16]

8.

Find the lowest natural frequency of transverse vibrating for the system shown in figure below using by Rauyleigh’s method. E = 2 x 10 N/m I = 10 m. [16]

or ld

.in

7.

Aj

nt

uW

*****

SET-2

Code No: 37195

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD R05 IV B.Tech. I Semester Supplementary, May/June – 2009

VEHICLE DYNAMICS (Automobile Engineering) Max. Marks.80 Answer any Five questions All questions carry equal marks

---

2.

A spring mass system has a period 0.25sec what will be the new period if the spring constant is increased by 50%. [8+8] A damping force having magnitude 2cos (2πt –π/4)N, gives 5cos2 π tm displacement. Calculate a. the energy dissipated during first 5seconds b. the energy dissipated during the first 3/4 seconds.

[8+8]

A periodic torque having a maximum value of 0.588 N-m at frequency corresponding to 4 rad/ sec is expressed upon a fly wheel suspended from a wire. The wheel has a moment of inertia of 0.12 kg/m2 and the wire has a stiffness of 1.176 N-m/rad. A dashpot applies damping couple of 0.392 N-m at an angular velocity of 1 rad/sec calculate a) The maximum angular displacement from rest position. b) The maximum couple applied to dash pot and c) The angle by which the angular displacement logs the torque. [16]

nt

3.

or ld

b)

A circular cylinder of mass 4kg and radius 15cm is connected by a spring of stiffness 4000N/m as shown in figure below it is free to roll on horizontal rough surface without slipping, determine the natural frequency.

uW

1.a)

.in

Time: 3 hours

The springs of an automobile trailer re compressed 0.1m under its own eight. Find the critical speed hen the trailer is passing over road with profile of sine wave whose amplitude is 8-mm and the wave length is l4m. Find the amplitude of vibration t speed of 60km/hr. [16]

Aj

4.

Contd…2

Set-2 5.

Find the natural frequencies and mode shapes of double pendulum.

6.

What are the factors affecting the vibration of vehicle and explain briefly. [16]

7.

Describe in details constructional features of the tubed and the tube less tyres for automobile use. Discuss also their relative merits and demerits. [16]

8.

Determine the natural frequency and mode shapes for the system shown below using influence coefficient method. [16]

or ld

.in

[16]

Aj

nt

uW

*****

SET-3 Code No: 37195 JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD R05 IV B.Tech. I Semester Supplementary, May/June – 2009

VEHICLE DYNAMICS (Automobile Engineering) Time: 3 hours

Max. Marks.80

--1.a)

A car having a mass of 1000kg deflects its springs 4cm under its load. Determine the natural frequency of the car in vertical direction. A torsion pendulum has to have a natural frequency of 5 Hz. What length of steel wire of diameter 2mm should be used for this pendulum? The inertia of the mass [8+8] fixed at the free end is 0.0098kg-m2 take G=0.83*1011 N/m.

or ld

b)

.in

Answer any Five questions All questions carry equal marks

A vibrating system in a vehicle is to be designed with following parameters. K=100N/m,c=2N-sec/m,m=1kg. Calculate the decrease of amplitude from its starting value after 3 complete oscillations and the frequency of oscillation. [16]

3.

A machine 100Kg mass has a 20Kg rotor with 0.5mm eccentricity. The mounting springs have K=85x103 N/m, ε = 0.02. the operating speed of the machine is 600rpm and the unit is consternated to move vertically. Find i) the dynamic amplitude of the machine ii) the force transmitted to the supports. [16]

4. a.

Explain the teem whirling (or) critical sound of a shaft. Prove that the wilrling speed for rotating shaft is some as the frequency of natural Tran square vibration. The following data refer to a shaft held a long hearing dia of shaft = 1.5cm length of shaft = 1m weight of disc at the centre of the shaft = 150N eccentricity of the C.G of the disc from the centre of the rotor = 0.03cm. [8+8] Find the fr3quencies of the system s shown in figure below k = 90 N/m l = 0.25m m1 = 2kg m2 = 0.5 kg. [16]

b.

Aj

nt

5.

uW

2.

Contd…2

Set-3 6.

A small reciprocating machine weights 26kg and runs at a constant speed of 6000 rpm. After installt6ionthe forcing frequency was found to be too close to the natural frequency of the system. Design dynamic vibration absorber of the nearest frequency of the system is to be at lest 20% from the excitation frequency. [16]

7.a. b.

Sketch and explain the features of tyre? Discuss in detail various factors affecting tyre life

8.

Using matrix iteration, find the natural frequency of the system (equal masses equally spaced on strings). [16]

or ld

.in

[10+6]

Aj

nt

uW

*****

SET-4

Code No: 37195

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD R05 IV B.Tech. I Semester Supplementary, May/June – 2009

VEHICLE DYNAMICS (Automobile Engineering) Time: 3 hours

Max. Marks.80

---

.in

Answer any Five questions All questions carry equal marks

Determine the natural frequency of the mass m=15kg as shown in figure below assumes that the cords do not stretch and slide over the pulley rim. Assume that the pulley has no mass. [16]

2.

A shock absorber is to be designed so that its overshoot is 10% of the initial displacement when released. Determine the damping factor. If the damping factor is reduced to one half this value, what will be the overshoot? [16]

3.

An industrial machine weighing 445Kg is supported on a spring with a statical deflection of 0.5Cm. if the machine has a rotating un balance of 25Kg-Cm, determine the force transmitted at 1200rpm and the dynamic amplitude at that speed. [16]

4.

The static deflection of the vibrameter mass is 20mg. The instrument when attached to machine vibrating with a frequency of 125cpm records relative amplitude of 0.03cm. Find the for the machine i) the amplitude of vibration ii) the maximum velocity of vibration iii) the maximum acceleration. [16]

Aj

nt

uW

or ld

1.

5.

Two bodies having equal masses as 60kg each and radious of gestation 0.3m are keyral to both ends of a shaft 0.80 m long. The shaft is 0.08 m in Demeter. For 0.3 m length, l0m diameter for 0.20m length and 0.09 diameters for rest of the length. Find the frequency of tensional vibrations. [16] Contd…2

Set-4 6.

A washing machine unit having a mass of 40kg is to be supported on three springs,. Each having spring constant K. The unit operates at 500 rpm. Determine the value of stiffness k if only 10% of the shaking force is allowed to be transmitted to the supporting structure. [16]

7.

What are the various type of tyres? Explain then in detailed.

8.

Find by HOLZER’s method the natural frequency of the torsionl system as shown in figure below when right end is fixed. [16]

uW

or ld

.in

[16]

Aj

nt

*****