vibration 10me62 june july 2013 (4)

8/10/2019 Vibration 10me62 June July 2013 (4)

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a)

o

sn

o.

Seventh

Semester

B.E.

Degree

Examination,

June/Jur

y

201

Mechanical

Vibrations

'

Time:

3

hrs.

Max.

Marks:100

Note:

Answer

any

FfWfuil

questions,

selecting

atleast

TWO

questions

jrom

each

part.

a'

l'j;

;"?l*T,,%3i',onic

motionl**I;"tr

and

check

rhe

sorution

graphicarry:

Ye:6

sin

(wt +

60.).

b. Develop

the

Fouriei

series

for

the curve shown

in

Fig.e.l

(b).

Fig.e.

t

(b)

2

a'

Explain

the

energy

rnethod

of

finding

naturar

frequency

of

a

spring_mass

system.

'

L,JJ,Jff*X,| H:;1

"i

*"

spring

controrled

simpre

o.,o.ir,*

,iJ*,

r,

-T--T

la

li

l

t

I

I

I

L-

4

(I0

Marks)

(10

Marks)

(08

Marks)

Fig.Q.2(b).

(06

Marks)


2/8

For

the

system

shown

in

10H2.

Take

kr

:2

N/mm

kz:

1.5

N/mm

k:

:3

N/mm

lq

:

ks:0.5

N/mm.

Fi'g.Q.2(c)

find

mass

m

t0ljl[E72

if

the

system

has

a

natural

liequency

of

(06

Marks)

iiD

Force

transmitted

to the

foundation.

(10

Marks)

PART

-

B

Explain

the

principle

of

working

of

i)

vibrometer

(seismometer)

;

ii)

Accelerometer.

(r0

Marks)

A

rotor

of mass

9.5kg

is

mounted

on

a

l2mm

horizontal

steel

shaft

midway

between

bearings

that

are

0.6m

apart.

The

mass

centre

of

the

disc

is

6mm

from

its

geomeiric

centre.

If

the

damping factor

is 0.1

and

the

shaft rotates

at

690

rpm,

determine

the

maximum

stress

in

the

shaft

and

compare

it

with

the

dead

load

stress

in

the

shaft.

For

steel

shaft

take

3a.

b.

4a.

b.

Fig.Q.2(c)

Show

that

the

ratio

of

successive

amplitudes

of

mass

in

a

underdamped,

viscously

damped

spring-mass

system

is

given

by

xo,\,-2nt-

=e-

Wnefe

d-

x.

-

-T-'

(10

Marks)

'

1/'-g

A

machine

of

mass

20kg

is

mounted

on

a

spring

and

dashpot.

The

spring

stiffness

is

l0

N/mm

and

damping

is

0.15

N/mm/s.

If

the

mass

is

initiaily

at

rest

ana"u

velocity

of

100

mm/s

is

imporled

to

it, determine:

i)

displacement

and

velocity

of

mass

as

a

function

of

time;

ii)

displacement

and

velocity

when

time

is

equalto

one

second.

(r0

Marks)

Derive

an expression

for

steady

state

amplitude

of

vibration

of

mass

in a

spring-mass-

damper

system

when

the

mass

is

subjected

to

harmonic

excitation.

Also

find

the

phase

angle

between

the

mass

and

excitation.

(10

Marks)

A

vibratory

body

of

mass

150kg supported

on

springs

of

total

stiffness

1050

kNim

has

a

rotating

unbalance

force

of

525

N

at

a

speed

oi

oo-oo.pr.

If

the

damping

factor

is

0.3,

determine:

i)

Amplitude

of vibration

and phase

angle.

iD

Transmissibilitv

ratio

and

5a.

b.


3/8

6a.

b.

7a.

b.

b.

Explain

the

principres

of

dynamic

vibration

absorber.

Derive

the

For

the

system

shown

in

Fig.e.6(b)

find

the

natural

frequencies

lrr

:

l0kg,

m2:

l5kg

and

k

)SZONT;.'

LONIE72

necessary

equations.

.

(10

Marks)

and

amplitude

ratios.

Given

(10

Marks)

Fig.Q.6(b)

Find

the

first

natural

frequency

and

draw

the

mode

shape

by

matrix

iteration

meth;d.

f"f."

t,

:

t

':

].1

:.k

and

m1

for

the

system

shown

in

Fig.e.7(a)

:

lD2

=

m3

:

m.

(10

Marks)

Using

Stodola,s

method.

shown

in

Fig.e7(b).

.

Fie.e.7(a)

determine

the

Iowest

natural

frequency

of

the

torsional

system

(10

Marks)

iv)

Analyzer,

(10

Marks)

(06

Marks)

(04

Marks)

J

-I.

a.

Fig.Q7(b)

Explain

the

rore

of

,

i)

Exciter;

ii)

Transducer;

iii)

Signar

conditioner

and

sed

in

experimental

modal

,rulvrir."-"

Describe the three tvpes

of

maintenance

schemes

given

below:

il

Breakdown

inainrenance.

li)

Preventive

maintenance.

Ii)

Condition-basedmaintenance.

Explain

briefly

rhe

following

,.ifroj,

oi,

il

wear

oeuris

monitoring.

oondition

monitoring:

ii)

Vibration

analysis.

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vibration 10me62 june july 2013 (4)

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