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Powertrain Noise & Vibration
N V KARANTH
Deputy Director, Head NVH Laboratory
The Automotive Research Association of India, Pune
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Necessity of NVH AwarenessNecessity of NVH Awareness
!"ND I A PR!PA#ATIN# T$P% !& %N%R#$'
N!I% I A "N(ANT%D !"ND'
NOISE - AUDIBLE
VIBRATION - TATILE
HARSHNESS - TATILE AND AUDIBLE
)*+H - .//H0
1
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Necessity for A!to"oti#e NVHNecessity for A!to"oti#e NVH
Noise Po22ution 3 45VR, 4P46 7 N4NP4
4ustomer A8areness !f Vehic2e Noise and Ride 4omfort
5ar9etabi2ity
Trend To8ards Hi:her Po8er and ma22er ie Po8er trains'
ound ;ua2ity
Desi:n !ptimiation
4onsistency In Production
.
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<
PASS BY
NOISE
SPL
OEL
RIDE
COMFORT
SOUND QUALITY
EXTERIOR
NOISE
INTERIOR
NOISE
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Sensiti#ity to Noise $ A"%it!'e an' (re)!ency
=
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Noise Sources-LevelsNoise Meter
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NVH assification
6y Noise Type Road
(ind
Drive2ine
?uea9 and Ratt2e
6y Vehic2e ystems 6ody
4hassis
Drive2ine
Vehic2e components 42imate contro2
system (ipers
eat motors 8itches
@
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NVH So!rces an' t*eir inter-reationNVH So!rces an' t*eir inter-reation
Power-trainPower-train
EngineEngine
TransmissionTransmission
Intake systemIntake system
Cooling systemCooling system
Exhaust systemExhaust system
Brake SystemBrake System
Road and TyreRoad and Tyre
WindWind
SuspensionSuspension
MountMount
VibrationVibration NoiseNoise
AirAir
OthersOthers
Harshness
Ride
Comfort
Sound
Quality
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So!n' +!aity
ound ?ua2ity );0 is the perceptua2
reaction to the sound of a product that
ref2ects the 2istenerBs reaction to the
acceptabi2ity of that sound for thatproductC the more acceptab2e, the
:reater the ;
6oth obective 7 subective
assessments need to be made
*/
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Pass-by Noise of A!to"oti#e Ve*ices
4ommunity Noise Po22ution')I-./1@EI!-.=10
5aFimum ound Pressure 2eve2 in Gd6)A0
measured at a distance of >'+m from the
vehic2e durin: vehic2e acce2erated to fu22
thrott2e
**
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Pass-by Noise of A!to"oti#e Ve*ices
*1
1 0 m
10 m 10 m 10 m 10 m
1 0 m
A BP
A’ B’P’
Centre line of
travel R= 50 m
Microphone (Height 1.2 m)
Minimum area covered with test road surface (Test Area)
Note: There shall be no large acoustically reflective objects with in the radius
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Pass-by Noise of A!to"oti#e Ve*ices
*.
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E,ISTIN PASS - B. NOISE LI/ITS (OR AUTO/OBILES
*<
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Interior Noise So!rces
*+
Intake SystemSurface Noise Radiation
Orifice Noise
System Vibrations
Exhaust SystemSurface Noise Radiation
Tailpipe Noise
System Vibrations
Transfer Behaviour
of Noise and Vibration
Vehicle
Interior Noise
Wind Noise
Drive Train Tyre
Wheel Suspension
Power TrainEngine and Gearbox Surface
Global Power Train Mode
Local Mode (P/T Mode, P/T Mount Brackets
Accessories)
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Interior Noise of Ve*ice
*=
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Power Train $En0ine Noise
Ty%es of En0ine Noise
Airborne Noise %Fhaust and Inta9e
tructureborne Noise Vibratin: surfaces
of en:ine structure and connected covers
*>
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Power Train $En0ine Noise
/ain E1citation (orces an' Str!ct!re
borne En0ine Noise 2
4ombustion Noise "nidirectiona2 :as 7Inertia forces cause combustion
noise'
5echanica2 Noise Reversib2e forces reated
due to cran9 mechanism induce mechanica2
noise'
*@
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Inta3e Noise
Noise #enerated due to
!penin: and c2osin: of the va2ves'
In2et air co2umn osci22ation by sharp
pressure pu2se from cy2inder'
*
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E1*a!st Noise
%Fhaust va2ve opens and re2eases :as at hi:h pressureinto the eFhaust system'
The principa2 component of noise - &undamenta2 and
harmonics of firin: fre?uency'
1/
Exhaust system design is a compromise between noise
reduction and engine power loss due to increase in back
pressure.
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!tc* Noise
42utch udder is basica22y torsiona2 vibration in thedrive 2ine durin: startin: of en:a:ement' This resu2ts
in rou:h starts and affects the ride comfort'
The maor causes are &riction characteristics of the c2utch i' e' re2ationship
bet8een s2ip speed and the friction coefficient
Torsiona2 vibrations due to variation in aFia2 2oad
resu2tin: from misa2i:nment of the drive2ine The c2utch peda2 vibrations can cause interior noise
prob2ems
1*
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Trans"ission Noise
Drive2ine noise and vibration sources resu2ts from
transmission of po8er from the en:ine to 8hee2s'
Trans"ission 0ear noise2
6endin: dynamics of the individua2 :ear tooth'
6oth bendin: and torsiona2 dynamics of :ear shafts'
Type and precision of :ears used'
&undamenta2 and second harmonics of the :ear mesh fre?uency -
most si:nificant components of :ear noise'
11
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Trans"ission Noise
Dri#es*aft an' Pro%eer s*aft 2
%Fcitation at rotationa2)fundamenta20 speed'
"niversa2 oint can provide eFcitation at secondorder
due to hi:h an:2es of coup2in:'
Rear 8hee2 drive vehic2es emp2oy a constantve2ocity oint in the center oint of t8o piece
prope22er shaft - provides aFia2 comp2iance in the
drive2ine 8hich decoup2es vibration from rear aF2e'
1.
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ear w*ine 0enerate' by 0ear "es* of t*e'ifferentia4
Vibration eFcited by tooth meshin: action of the aF2e :ear
set'
Noise is narro8 band and annoyin: even at 2o8 2eve2s in the
passen:er compartment of the vehic2e'
Noise due to resonance mode of the aF2e may be reduced
by a2terin: aF2e mass and stiffness so that resonance 2ie
outside the norma2 operatin: ran:e'
Dri#eine-A1e Noise
1<
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Bet Noise
J Impact :enerated by co22ision oftooth of be2ts a:ainst bottom2and of
sproc9et at the be:innin: of
meshin:
J Transverse and torsiona2 vibrationof the be2t
J Airf2o8 bet8een be2t and pu22ey at
meshin:
J &riction bet8een be2t and pu22eyand s2ip of the be2t
J Vibration of the pu22ey
1+
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*ain Noise
J Impact of chain 8ith sproc9et and
po2y:ona2 effect
J Ro22er impacts of chain at hi:her
speedJ Torsiona2 vibration of camshaft
causes si:nificant tension f2uctuation
in chains and ma:nifies chain
transverse vibrationsJ 4hain natura2 fre?uencies
J 4over fre?uencies
1=
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Tyre noise is :enerated by,
Ro22in: contact of the tyre
)a resonant system0 8ith surface of
random rou:hness )the road0'
Trea' #ibration - Radia2 vibration of
tread - primary contributor noise'
Trea' s)!ir" - Loca2ied 2atera2
vibration of tread - hi:h fre?uency part
of noise spectrum'
1>
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So!rce5Pat*5Recei#er
1@
Source - causes disturbance
Path - may isolate or amplify disturbance
Receiver - responds to disturbance NVH strategy
Source X Path Sensitivity = Response
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NVH Toos an' /et*o's
ource identification ound Intensity ound Acoustic Ho2o:raphy
5oda2 ana2ysis %Fperimenta2 5oda2 Testin: !peratin: Def2ection hapes !perationa2 5oda2 Ana2ysis
!peratin: 5easurements !rder trac9in:
Noise Path Ana2ysis 4A% ound ;ua2ity
ound synthesis ury %va2uation
1
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So!n' So!rce I'entification
ound Intensity !btain vector ?uantity of sound at various pointsE:rid 2ocations
around the test artic2e usin: a 1-microphone probe
./
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Acoustica2 Ho2o:raphy and 6eam &ormin:
Ho2o:raphy is Gmeasurements of a wave field are
made on a two dimensional surface and is used to calculate
wave field in three dimensional space to obtain a visua2
representation of the sound radiated from a test artic2e usin: a
microphone array'
.*
Vehicle Exterior Vehicle Interior Engine Noise
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Noise ontrib!tion of Vario!s o"%onents of En0ine
.1
E1*a!st
syste"-678
Inta3e syste"-
978
Ot*ers-678
En0ine Boc3-
678
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/o'a Anaysis
..
E/A /ODE 2 6:; H< (EA /ODE2 6:7 H<
E/A /ODE 2 =>9H< (EA /ODE2 =?= H<
E,PERI/ENTATION (E ANAL.SIS
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ODS $ O%eratin0 Defection S*a%es
!peratin: Def2ection hapes 3
5easure motion transmissibi2ity
functions re2ative to one fiFed
2ocation, ) acci E acc 0 at a 2ot of
points, 2i9e 8ith 5oda2 Ana2ysis It 2oo9s 2i9e a duc9, but ITB N!T A
D"4K )mathematica22y, these are
forced response shapes, not mode
shapes - itBs N!T moda2 ana2ysis0
4an be time-domain or fre?uency
domain
Laser Vibrometer
.<
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Vibro-aco!stic Pre'iction Tec*ni)!e
.+
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/!ti-bo'y 'yna"ics
4omponents mode2ed as ri:id, 2umped mass part 4onnections throu:h sprin:s and dampers "nderstand traectory and time-response of system
As in suspension systems, steerin: systems, ri:id-bodyvibration modes of po8ertrain )bounce, pitch, ro220
Lo8 fre?uency )be2o8 *// H0 ADA5 is popu2ar 4A% soft8are for this type of mode2in: "sed as support for 6oundary 4ondition for &%5
.=
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Noise Pre'iction by (E/ Tec*ni)!e
&% 5oda2 Ana2ysis
Dynamic Response Ana2ysis
4oup2ed Ana2ysis
.>
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BE/ Tec*ni)!e
It is one of Numerica2 techni?ues
used to so2ve the acoustic prob2ems
2i9e &inite %2ement 5ethod)&%50'J In 6%5 on2y the boundary of the
domain is dicsretied' &or comp2eF
#eometries the 6%5 mode2in: 2eads
to si:nificant savin:s of manpo8erand computationa2 time'
.@
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Ot*er AE Tec*ni)!es
tatistica2 %ner:y Ana2ysis Hi:her &re?uency computationa2 NVH
techni?ue, usua22y used at fre?uencies hi:her
than .// H in automotive app2ications
4omputationa2 &2uid Dynamics App2ied to f2uid-f2o8 and air-f2o8 )e':' 8ind
noise0
.
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orreation Between (E Tec*ni)!e an' E1%eri"enta Testin0
</
Test /o'e
Initia (R(s
/o'e Test
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orreation Between (E Tec*ni)!e an' E1%eri"enta Testin0
<*
9.70E+01
1.17E+02
1.37E+02
1.57E+02
1.77E+02
1.97E+02
2.17E+02
630 800 1000 1250 1600 2000 2500 3150
4entre 6and &re?uency in M H, M
V i b r a t i o n V e 2 o c i t y
LOC 01 LOC 2
LOC 03 LOC 07
200 250 315 400 500 630 800 1000 1 250 1 600 2000 2 500 3 150 4 000
Centre Band Frequency (Hz)
V i b r a t i o n V e l o c i t y_
V-Loc 1 V-Loc 2
V-Loc 3 V-Loc 7
VIBRATION VELOCITIES WITH
COMBUSTION FORCES
/EASURED VIBRATION
VELOITIES
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Aco!stica Treat"ent
<1
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Ri'e o"fort
<.
Ride - Tactile And Visual Vibrations, 0 - 25 Hz
Vibrations - Noise Aural (25 Hz - 20 kHz)
EXCITATION
SOURCES
Road roughness
Tire/Wheel
Driveline Engine
VEHICLE
DYNAMIC
RESPONSE
VIBRATIONS
Ride Perception
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Ve*ice Ri'e o"fort
Ride comfort in a vehic2e is a subective perception norma22yassociated 8ith 2eve2 of comfort eFperienced durin: trave22in: in
a vehic2e'
Perceived ride is cumu2ative effect of many factors'
In the vibration spectrum,
Ride - / -1+ H
Noise - 1+H - 1/KH'
Ride is a tacti2e and visua2 vibrations'
<<
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Ve*ice Ri'e o"fort
Vertica2 fre?uencies 8hich fee2s most uncomfortab2e fa22s in the
ran:e of 1/H - 1//H'
&ati:ue occurs most rapid2y 8hen subected to vibrations in the
ran:e of <H to @H or in the 2o8 band be2o8 /'>+ H 8herediiness and motion sic9ness can resu2ts
Latera2 or foreEaft fre?uencies in the same ran:e are a2so
uncomfortab2e because it disturb ba2ance of inner ear'
I!1=.* for eFposure 2imits of 8ho2e body vibrations and
I!+.< for eFposure to hand arm vibrations'
<+
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Noise Iss!es '!rin0 Ve*ice O%eration an' /aintenance
%n:ine
5ountin: of en:ine and top cover
5ismatch of mass bet8een piston and connectin: rods
4ran9 shaft ba2ancin:
Torsiona2 vibration
%Fhaust
Loose mountin: 6rac9ets
Lea9a:es
4orrosion
6aff2es in muff2ers
hie2din: materia2
<=
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Noise iss!es '!rin0 Ve*ice o%eration an' "aintenance
Trans"ission
/o!ntin0 of 'ifferentia an' s*oc3 absorbers
!tc* @!''er
Pro%eer s*aft .o3e ai0n"ent /isai0n"ent of r!bbers an' S%it s*aft syste"s
Bo'y
Vibrations of ire *arness t*at are ro!te' t*ro!0* brac3ets we'e' to bo'y
Steerin0
P!"% bets an' rac3 "ec*anis"s
Door
Swein0 of r!bber seas or si%%in0 action of r!bber seas for win'ows
/o#in0 0ass win'ows act!ators are not 'esi0ne' for re)!ire' tor)!e
<>
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Ve*ice
teerin: Imba2ance of the 8hee2 8i22 induce vibration in
steerin: 8hee2
Looseness in trac9 and tie rods
6a22 oint 8earin: off
Knuc92e bearin:s 8earin: off
(hee2
Loose 8hee2 caps
(ashers for fitments
Nut conica2 and f2at )conica2-inside, f2at-outside0
<@
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Ve*ice
Pane2s 6onnets, 2atch
oint 8hich are not 8e2ded homo:eneous2y
After accident some of the pane2s are not oined
proper2y
Dashboard
Air-conditionin: unit
eat
2idin: rai2s
<
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Ve*ice
Trun9 Latches and hin:es, Tension bar inside
uspension Rubber mounts, functionin:
(ipe mechanism 5otors, (iper pads
Timin: drives 4hains noise are overcome by usin: be2t
Accessories
Va2ve mechanisms
Tyre
Pump noise
6attery
&an noise
Pipes
+/
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ENINE NOISE- AN OVERVIE
+*
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De"an' & Necessary
To'ayCs De"an'
*' Li:hter %n:ines 8ith hi:h compressions,
faster combustion 7 sma22er fue2
consumption'1' Lo8 noise en:ines4
*y it is Necessary
*' trin:ent Noise Le:is2ation
1' 4omfort
+1
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Brea3 'own of %ass by noise in a ty%ica #e*ice
+.
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*y Re'!ce En0ine Noise
5ore than +/ of sound po8er is radiated from
en:ine '
%n:ine 2oad carryin: 4omponents and Non-Load
carryin: covers are responsib2e for noise radiation'
+<
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Noise Baance of en0ine
++
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Noise eneration Process in Diese en0ines
+=
Research by LUCAS CAV
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Ty%es of En0ine Noise
J Airborne Noise %Fhaust and Inta9e
J tructure borne Noise Vibratin: surfaces of
en:ine structure and connected covers
+>
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Para"eters To Be /eas!re'-
J ound Pressure Leve2 at *mtr distance
J ound Po8er Leve2
J ound ;ua2ity
ritica O%eratin0 Para"eters2
J Rated and 5aFimum Tor?ue
J 5aFimum Rpm'
J Acce2eratin: conditions
+@
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ENINE NOISE /EHANIS/ /EASURE/ENT
ound Po8er 5easurement
I! .></ and I! =*< series of standards
ound Pressure 5easurement &re?uency
ana2ysis by narro8 band and octave ana2ysis
+
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E)!i#aent En0ine Syste"
=/
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/ain e1citation forces
J as forces
J Inertia (orces
J /ec*anica I"%acts
=*
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/ain E1citation (orces an' Str!ct!re borne En0ine Noise
4ombustion Noise "nidirectiona2 :as 7
Inertia forces cause combustion noise'
5echanica2 Noise Reversib2e forces
created due to cran9 mechanism
induce mechanica2 noise'
=.
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/ain Para"eters to be controe'
J %Fcitation &orces
J Dynamic 4haracteristics of structure
J Noise Radiatin: characteristics of structure
=<
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Noise Ra'iation /ec*anis"
=+
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.LINDER PRESSURE AND NOISE SPETRA O( A T.PIAL DIESEL ENINE
==
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NOISE SOURE IDENTI(IATION TEHNI+UES
#reatest Noise Reduction is achieved by identifyin:
the 5aor Noise ource and its 4ontro2'
Partia2 %nc2osure Techni?ue'
Acoustic Intensity Techni?ue
!rder Trac9in: Ana2ysis
Near &ie2d Acoustic Ho2o:raphy
=>
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SOURE IDENTI(IATION 2 PARTIAL ENLOUSRE TEHNI+UE
Traditiona2 imp2e Techni?ue'
No pecia2ied 5easurement %?uipment or &ie2d Is
Re?uired'
Time 4onsumin:
ound Insu2ation Treatment is must and cost2y'
5ay 4han:e %n:ine Performance
Accuracy Depends on Insertion 2oss of oundInsu2ation Treatment'
=@
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SOURE IDENTI(IATION 2 PARTIAL ENLOUSRE TEHNI+UE
5a9e the Desired 5easurements 8ith en:ine
comp2ete2y eFposed'
App2y the ound Insu2ation treatment to the entire%n:ine'
Repeat the 5easurement '
4a2cu2ate the Insertion 2oss of ound Insu2ation
treatment confirm that it shou2d be O or */d6'
=
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SOURE IDENTI(IATION 2 PARTIAL ENLOUSRE TEHNI+UE
5a9e the ound 5easurement 8ith each noise
source eFposed individua22y'
Repeat the 5easurement a:ain 8ith sound insu2ation
treatment enc2osin: entire en:ine to ensure the
insertion 2oss of treatment'
4a2cu2ate the contribution of each source by
comparin: tota2 sound pressure 2eve2 and individua2
source'
>/
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SOURE IDENTI(IATION 2 AOUSTI INTENSIT. TEHNI+UE
J ound Intensity I)t0
Instantaneous rate of f2o8 of ound ener:y per unit
surface area in the direction of 2oca2 instantaneousacoustic partic2e ve2ocity' This is a vector ?uantity and
is e?ua2 to the product of the instantaneous sound
pressure p)t0 at a point and the associated partic2e
ve2ocity v)t0'
>*
)v(t p(t)* )I(t −−
=
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SOURE IDENTI(IATION 2 AOUSTI INTENSIT. TEHNI+UE
>1
• Sound Intensity: I(t):
It is expressed in Watt per Sq.meter.
Sound Power Level: SW : Sound Power is the measure of total sound energy
radiated by source.It can be calculated as,
S t I SW Q0)=
It is expressed in “ Watt “
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SOURE IDENTI(IATION 2 AOUSTI INTENSIT. TEHNI+UE
ISO 9614 Series is available or calculation ofSound !ower b" sound intensit"
#easurement$
5ethodo2o:y
*'cannin: 5ethod
1'Discrete point 5ethod'
Procedure
--Discretie the 5easurement urface into Gn
sma22 se:ments )i0'
><
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SOURE IDENTI(IATION 2 AOUSTI INTENSIT. TEHNI+UE
4arryout the norma2 ound Intensity GI)i0
5easurement at each divided se:ment )i0 of
area Gs around the source'
-- 4a2cu2ate a po8er for each e:ment GPi
-- &ina22y 4a2cu2ate Tota2 ound Po8er G('
>+
si I !i Q0)=
∑==
n
i
!i SW *
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SOURE IDENTI(IATION2 ORDER TRAIN ANAL.SIS
!rder is inte:er or ha2f inte:er mu2tip2e of
cran9shaft rotationa2 fre?uency
!rders are cate:arised as G%venorders,!dd orders and ha2f en:ine !rders
%ven !rders are the mu2tip2es of firin:
fre?uency and provides the basic character of
noise'
>=
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SOURE IDENTI(IATION2 Or'er trac3in0 Anaysis2 2 Utiity
To identify the noise :enerated by rotationa2
vibrations ,critica2 speeds and resonances'
It provides information of the noise 8ith
respect to en:ine rpm'
>>
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SOURE IDENTI(IATION2 Or'er trac3in0 Anaysis
5%TH!D
ynchronous amp2in: 5ethod'
peed 8eep
Data can be Disp2ayed by
(aterfa22 Dia:ram
4ampbe22 Dia:ram'
>@
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SOURE IDENTI(IATION2 Or'er trac3in0 Anaysis
In 4ampbe22 Dia:ram ,the fre?uency spectrum
of vibration is disp2ayed for different en:ine
RP5 and pea9 amp2itudes are p2otted 8ithfre?uency onto vertica2 aFis and the speed on
the horionta2 aFis 'The en:ine orders are
mar9ed a2on: dia:ona2 2ines'
@/
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SOURE IDENTI(IATION2 NEAR(IELD AOUSTI HOLORAPH.
The basic princip2e of acoustic ho2o:raphy is
-G to measure cross-spectra bet8een a set ofreference transducers and the ho2o:ram
microphones over a p2ane c2ose to the
radiatin: surface'
@*
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SOURE IDENTI(IATION2 NEAR(IELD AOUSTI HOLORAPH.
&rom this type of measurement a comp2ete .-D
description of the sound fie2d can be identified interms of ound intensity, partic2e Ve2ocity, ound
pressure 2eve2s, sound po8er and radiation
patterns'
@1
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Str!ct!ra Res%onse
J It is essentia2 to understand the response of
the structure to the app2ied forces
J %va2uated by computin: the transfer
functions bet8een the eFcitation force and
vibrations at various 2ocations
@.
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Str!ct!ra Res%onse2 /o'a Anaysis
J Natura2 &re?uencies, dampin: va2ues and
mode shapes are determined
J 5ode shapes are the deformation patterns
associated 8ith the natura2 fre?uencies
@<
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/o'a set !%
@+
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NOISE PREDITION TOOLS FNPTG
&inite %2ement Ana2ysis
Ray2ei:h Inte:ra2 5ethod
6oundary %2ement 5ethod
tatistica2 %ner:y Ana2ysis'
@=
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NPT2 (inite Ee"ent Anaysis
5athematica2 Representation of the structure 8ith
respect to the :eometry, density)mass0,
stiffness, materia2 Properties and dampin: bydiscretiin: the structure into sma22 se:ments ca22ed
as G%2ements bounded by end points 9no8n
asGnodes
@>
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NPT2 (inite Ee"ent Anaysis 2 /o'a Anaysis
It determines the free free ei:en va2ues 9no8nas natura2 fre?uencies and ei:en vectors as
mode shapes'
It is very usefu2 to va2idate the finite e2ementmode2s of the structures usin: %Fperimenta2
5oda2 Testin:'
It :ives re2ative amp2itude of different parts of
the structure in particu2ar mode,but it does
not :ive any information about abso2ute
response of the structure'
@
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NPT2 (inite Ee"ent Anaysis 2Har"onic Res%onse Anaysis
It is a2so 9no8n as forced response ana2ysis'
It is used to predict the structura2 response
caused by a defined dynamic eFcitation'
&rom the dynamic Response characteristics
the surface ve2ocities are computed and 8i22
be used as input for 6%5 and
Ray2ei:h Inte:ra2 5ethod to find out sound
po8er and radiation ratio'
/
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NPT2 (inite Ee"ent Anaysis 2Har"onic Res%onse Anaysis
Preparation of &inite %2ement 5ode2 of the%n:ine 4omponents 2i9e 4ran9case ,oi2
pan,shaft,covers,etc'
Va2idation of &inite %2ement 5ode2s of en:ine
compnents usin: &inite %2ement 5oda2
Ana2ysis in &ree &ree 4ondition and
%Fperimenta2 5oda2 Testin:'
App2ication of correct 6oundary 4onditions'
4omputation of urface Ve2ocities by &orced
Response Ana2ysis'
*
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NPT2 RA.LIEH INTERAL /ETHOD
It is an approFimate radiation inte:ra2 in 8hich
it is assumed that the radiatin: surface is f2at
and 2ies in an infinite f2at baff2e and surface ofstructure is covered 8ith a finite number of
pistons 8hich move perpendicu2ar to the
surface 8ith certain Ve2ocities'
1
S.STE/ATI NOISE REDUTION STRATE.
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S.STE/ATI NOISE REDUTION STRATE.
.
Experimental Noise
Source Identification
Va2idated &%
5ode2
Yes
Preparation of
FE Model of
Noisy Component
Prototype of
Noisy Component
No
Refined FE
Model
Modal Data or FRF
Matching
Power train
Noise ontro
Experimental
Modal TestingAnalytical
Modal Analysis
S.STE/ATI NOISE REDUTION STRATE.
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S.STE/ATI NOISE REDUTION STRATE.
<
Noise Prediction
using BEM
Structural Modification on
FE Model
Target Noise
Reduction is
Achieved
Product with
Reduced NoiseStructural Modification
on Prototype
Yes
No
Yes
No
Required
Noise Reduction is
Achieved
(using BEM)
Vai'ate' (E /o'e
Dynamic Response
Analysis using FEM
t '
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ase st!'y
En0ine Asse"by Str!ct!ra
O%ti"i<ation for Low Noise Ra'iation
+
St t O ti i ti E i I ( i St
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Str!ct!ra O%ti"i<ation E1ercise In#o#es (oowin0 Ste%s
Setting up target for Sound Power Level (SWL) reduction from base
Preparation of iterative models of varying stiffness by addition of
stiffners and ribs on crankcase and oil pan using Hypermesh
Forced esponse !nalysis " !pplication of unit force at bearing
location on F# model to predict surface vibration velocities
!coustic #ngine $esh Preparation using L$S % &irtual Lab Surface &elocity prediction of the assembly using L$S % &irtual
Lab '&H module
Surface velocity data transfer on acoustic meshed model
SWL Prediction and comparison with base SWL using L$S %
&irtual Lab !coustics
Selection of optimied models based on maimum SWL reduction
and minimum weight increase
=
E i t N i S I' tifi ti
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E1%eri"enta Noise So!rce I'entification
>
Identification of noise pockets by
measuring/mapping noise at one
plane/surface .
Sound intensity/Acoustic holography
Setting up target for Sound Power Level (SWL) reduction from base
&% 5 d 2 f N i 4 t
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&% 5ode2 of Noisy 4omponent
@
FE model for natural frequency correlation.
Modal analysis
V 2id t d &% 5 d 2 f N i 4 t
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Va2idated &% 5ode2 of Noisy 4omponent
En0ine Asse"by
8 Variation in nat!rafre)!ency
%Fperiment &%-imu2ation
&re?uency Dampin: &re?uency
* $* * /'1=
1 $1 1 <'1=
. $. . */'*
< $< < /'+=
+ $+ + <'@<
FE model for natural frequency correlated.
Dyna"ic Res%onse Anaysis
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Dyna"ic Res%onse Anaysis
*//
Forced esponse !nalysis " !pplication of unit force at bearing location
on F# model to predict surface vibration velocities and compared with
eperiment*
S!00este' /o'ification 92 /ain Ho!sin0
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S!00este' /o'ification-92 /ain Ho!sin0
*/*
Base Model
S!00este' /o'ification2 ear bo1 co#er
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S!00este' /o'ification2 ear bo1 co#er
*/1
S!00este' /o'ification62 !tc* Ho!sin0
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S!00este' /o'ification62 !tc* Ho!sin0
*/.
Base Model
Preparation of iterative models of
varying stiffness by addition of
stiffners and ribs on crankcase and
oil pan using Hypermesh
En0ine /o'e Str!ct!ra & Aco!stic
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En0ine /o'e $ Str!ct!ra & Aco!stic
*/<
!coustic #ngine $esh Preparation using L$S % &irtual Lab
Noise Pre'iction
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Noise Pre'iction
*/+
orreation /eas!re' an' Pre'icte' So!n' Intensity /a%s
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orreation- /eas!re' an' Pre'icte' So!n' Intensity /a%s
*/=
Aco!stic Bo!n'ary con'itions
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Aco!stic Bo!n'ary con'itions
+mposing fre,uency dependent surface vibration velocities
generated earlier on engine assembly acoustic mesh and preparation of +S- field point mesh
*/>
ISO Field Point Mesh
Acoustic
Mesh
Reflecting Surface
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SL o"%arison between Base an' Pro%ose'
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SL o"%arison between Base an' Pro%ose'
*/*/
Modification
Base
:'BFAG re'!ction fro" Base SL
Noise re'!ction ac*ie#e' by /o'ifications
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%arious desi&n iterations are compared on the &rounds
of percenta&e increase in assembl" wei&ht due toaddition of ribs' stiffeners etc$ and correspondin&
reduction in SW( level
)onsideration of noise aspects earlier in the desi&n
phase &ives strate&ic advanta&e to en&ine
manufacturers as the" can deliver low noise radiatin&
en&ines with minimum increase in en&ine wei&ht
Noise re'!ction ac*ie#e' by /o'ifications
/o'ification n!"ber Noise re'!ction in
'BFAG
ei0*t increase F30G
6ase
5odification-*
5odification-1 $$ $
5odification-.
**/
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INTAK% AND %HA"T$T%5
***
Inta3e An' E1*a!st Syste" o%ti"isation
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Inta3e An' E1*a!st Syste" o%ti"isation
Re?uire parameters
Insertion Loss )IL0
6ac9 Pressure )6P0
Transmission 2oss )TL0
**1
Sc*e"atic Test Set!%
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Sc*e"atic Test Set!%
**.
Insertion
Loss
Trans"issionLoss
/EASURE/ENT O( IL ON E,ISTIN & TARET SILENER
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/EASURE/ENT O( IL ON E,ISTIN & TARET SILENER
**<
IL = SPL1 – SPL2
Schematic of IL measurement
TEST SILENCER
Engine
SPL1
SPL2
Engine
WITHOUT SILENCER
/EASURE/ENT O( BP ON E,ISTIN & TARET SILENER
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/EASURE/ENT O( BP ON E,ISTIN & TARET SILENER
**+
Test silencerEngine
Pressure taps
E,ISTIN SILENER (OR BP
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E,ISTIN SILENER (OR BP
**=
Press!re Distrib!tion Veocity Vectors Distrib!tion
BP Predicted by CFD in mm Hg
Measured BP was in mm Hg
Variation of XX % is observed. This is generally considered as an acceptable
level considering the number of assumptions in the input and model during simulation.
SUESTED /ODI(IATIONS O( E,HAUST S.STE/
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SUESTED /ODI(IATIONS O( E,HAUST S.STE/
**>
Tube 1
Tube 2
Tube 3Tube 4
!""le 1 !""le 2
Chamber 3Chamber 2
Chamber
1
!""le 2
Tube 2
Tube 1
!""le 1
Tube2
Ch!#ber 3Ch!#ber 2Ch!#ber 1
!""le 2
Tube 1
Tube 2
!""le 1 !""le 2
Chamber3Chamber2Chamber1
O/PARISON O( TL RESULTS O( E,HAUST S.STE/
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O SO O SU S O US S S
**@
RESULTS O( BP AND IL /EASURE/ENTS ON PROTOT.PES
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**
5uff2er
5ode2 E1istin0
Benc*"ar3Desi0
n9Desi0n
Desi0n
6sa"%e
9sa"%e
sa"%e6
Tar0etsa"%e
9
6P
)mmH:0
p ? r s t> u v
IL)d6A0
F y d a b c