1

3. Noise and Vibration design

1. Basic of Vibration and Noise

1.1 Vibration 1.2 Noise 2. Automotive Vibration and Noise

2.1 Noise and Vibration-Management table 2.2 Representative examples of automotive noise and vibration 3. Analysis technology and Embodiments

4. Vehicle and Noise (from the standpoint of pollution response)

Lecturer: Professor Dr. H.Morimura

Tokyo Institute of Technology

2

Fig.0-1 Long-term Transition of Development on the interior noise

(at a speed of 100km/h in top gear)

◆ ： Data of Motor Fun

ATZ-Interior noise Zone

(prediction)

3dB reduction / 10years(ATZ)

4dB reduction / 10years(M / Fun)

3 Fig.0-2 Environmental advances in vehicle development

/www.top500.org/

1PFlops：2009 1000times / 10 years !!!

100times / 1 year !!!

Gfl

op/s

4

1.1 Vibration 1.1.1 Free vibration

0)()()( tkxtxctxm

Fig.1.1 Single Degree of Freedom Model

mass

m

x

spring k [N/m]

damper c [Ns/m] forcerestoringtkx

dampingViscoustxc

forceInertiatxm

ntDisplacemex

：

：

：

：

)(

)(

)(

5

Free damped vibration

ζ＝0 :Free vibration

ζ＜1 :Damped vibration

ζ＝1 :Critical vibration

ζ＞1 :Over damping

－ ζ=0

－ ζ=0.2

－ ζ=1

－ ζ=1.5

fig. 1.2 Vibration shape

-1

-0.5

0

0.5

1

0 0.5 1 1.5 2

時間　t(s)

変位

　x(m

)

time t (s)

dis

pla

cem

ent

x

(m)

frequency natural Damped:1

frequencyangular Natural:/

ratio Damping:/

tcoefficien damping Critical:2

cos

0)()()(

2

0

nd

n

c

c

dtn

mk

cc

mkc

here

texx

tkxtxctxm

6

1.1.2 Forced Vibration

Fig.1.3frequency response of single degree of freedom system

(Displacement / excitation Force)

F0sinωｔ mass

m

x

spring k [N/m]

damper c [Ns/m]

2

22 2

0,0

0

1/2arctan

21/1/

/,2/

force staticfor deflection

sin)()()(

XsX

thenmkc

FXkXF

tFtkxtxctxm

n

ss

正弦波入力に対する振幅倍率

0

1

2

3

0 1 2 3

周波数比, Hz

振幅

倍率

, ｜

X/X

s｜

ζ =0.01

ζ =0.2

ζ =0.5

ζ =1

Amplitude ratio of the sine-wave input

Am

pli

tud

e ra

tio x／

xｓ

Frequency ratio β

加振力に対する変位の位相

-3.14

-1.57

0.00

0 1 2 3

周波数比　β

位相

　θ

, ra

d

ζ =0.01

ζ =0.2

ζ =0.5

ζ =1

the Phase of displacement of Sinusoidal input

Phas

e θ

rad

Frequency ratio β

7

the effects of Stiffness

Fig.1.4 compliance to the effects of Stiffness (spring constant)

0

1

2

3

4

5

6

0 0.5 1 1.5 2 2.5 3

Frequency ratio ω

Com

pli

ance

｜X/F

｜

k=4

k=1 k=0.25

the effect region of increasing Stiffness

Stiffness Dynamic/Compliance/

Impedance/Mobility/

massApparent /eAcceleranc/

sin)()()(

00

00

00

0

：：

：：

：：

xFFx

xFFx

xFFx

tFtkxtxctxm

F0sinωｔ mass

m

x

spring k [N/m]

damper c [Ns/m]

Accelerance = Inertance

Compliance = Receptance, Admittance, Dynamic flexibility

8 Fig. 1.5 compliance to the effects of Mass

0

0.5

1

1.5

2

2.5

3

0 0.5 1 1.5 2 2.5 3 Frequency ratio ω

Com

pli

ance

｜X/F

0｜

m=4 m=1 m=0.25

the effect region of increasing Mass

F0sinωｔ mass

m

x

spring k [N/m]

damper c [Ns/m]

the effects of Mass

9

The effect of Damping

Fig.1.6 compliance to the effects of Damper

0 0.5 1 1.5 2 2.5 30

1

2

3

4

5

6

7

8

9

10

(ab

s)

(rad/sec)

ー ζ＝０．０５

ー ζ＝０．１

ー ζ＝０．２

ー ζ＝０．５

Com

pli

ance

׀

x/F

0 ׀

Frequency ratio ω

F0sinωｔ mass

m

x

spring k [N/m]

damper c [Ns/m]

10

1.1.3 vibration cutoff

Transmitted force

through spring

Fk＝kx

Ft = Fk + Fc

Transmitted force

through damper

Fc ＝cx’

Fig.1.7 transmissibility of force

Ft ／ F0 : transmissibility of force

Fc

x

x’

spring k [N/m]

damper c [Ns/m]

F0sinωｔ mass

m Ft

2222220

20

4141/

2121/

FF

jjFF

t

t

11 Fig.1.8 Force Transmissibility

0.1

1

10

0 1 2 3 4β =ω ／ω 0

τ=F

t／F0

ζ =0.05

ζ =0.1

ζ =0.2

ζ =0.4

ζ =0.8

2

mass

m

x

spring k [N/m]

damper c

[Ns/m]

F0sinωｔ Fｔ

Force transmissibility is reduced

with β increase and ζ decrease

Force Transmissibility

12 0 1 2 3 4 5 6 7 8 9 10

0

0.2

0.4

0.6

0.8

1

1.2

1.4

時間　ｔ　(s)

ｘ0, x

(m)

t0=T0 Time t (s)

0 1 2 3 4 5 6 7 8 9 100

0.2

0.4

0.6

0.8

1

1.2

1.4

時間　ｔ　(s)

ｘ0, x

(m)

t0 Time t (s)

0 1 2 3 4 5 6 7 8 9 100

0.5

1

1.5

2

時間　ｔ　(s)

ｘ0, x

(m

)

t0 Time t (s)

0 1 2 3 4 5 6 7 8 9 100

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

時間　ｔ　(s)

ｘ0, x

(m)

Period T0 Time t (s) mass

m

x

spring k [N/m]

damper c [Ns/m]

x0

1.1.4 Transient vibration

where c =0

Period Natural:/1

frequency Natural:2/

frequencyangular Natural:/

00

0

fT

f

mk

n

n

Fig.1.9 Transient vibration

13

mass

m

x

spring k [N/m]

damper c [Ns/m]

x0

0 1 2 3 4 5 6 7 8 9 100

0.2

0.4

0.6

0.8

1

1.2

1.4

時間　ｔ　(s)

ｘ0, x

(m)

0 1 2 3 4 5 6 7 8 9 100

0.5

1

1.5

2

2.5

時間　ｔ　(s)

ｘ0, x

(m

)

0 1 2 3 4 5 6 7 8 9 10-1.5

-1

-0.5

0

時間　ｔ　(s)

ｘ0, x

(m

)

Time t (s)

Time t (s)

Time t (s)

t0=T0

Fig.1.10 Transient vibration

14

mass

m

x

spring k [N/m]

damper c [Ns/m]

x0

0 1 2 3 4 5 6 7 8 9 100

0.5

1

1.5

2

時間　ｔ　(s)

ｘ0, x

(m

)

0 1 2 3 4 5 6 7 8 9 100

0.5

1

1.5

2

時間　ｔ　(s)

ｘ0, x

(m

)

0 1 2 3 4 5 6 7 8 9 100

0.5

1

1.5

2

時間　ｔ　(s)

ｘ0, x

(m

)

0 1 2 3 4 5 6 7 8 9 100

0.2

0.4

0.6

0.8

1

1.2

1.4

時間　ｔ　(s)

ｘ0, x

(m

)

Cycle time T0

period T0/2

Time t (s)

Time t (s)

Time t (s)

Time t (s)

c=0

T0=1/f0=1/{ω0/(2π)}

＝cycle time

Fig.1.11 Transient vibration

15

0

0.2

0.4

0.6

0.8

1

0 1 2 3 4

振幅

比D

isp

lace

men

t r

atio

x/x

0

t0 / T0

x0

t0

Fig.1.12 amplitude ratio of transient vibration

c=0

T0=1/f0=1/{ω0/(2π)}

＝cycle time

mass

m

x

spring k [N/m]

damper c [Ns/m]

x0

16

Displacement

input of the

road

Vibration

of body

Engine

Vibrating

force

Engine

Vibration

mass

m

x

spring k [N/m]

damper c [Ns/m]

x0

F0

mass

m

x

spring k [N/m]

damper c [Ns/m]

Fig.1.13 example of Transient vibration

17

• Figure is the time limit of

workers Sitting while

exposed to vibration.

Vertical direction ：

• The sensitivity is highest

when exposed to vibration 4Hz to 8Hz.

Back and Forth direction ：

• The sensitivity is highest

when exposed to vibration around the 1 Hz .

1.1.5 Vibration sensitivity of the human body

Fig.1.14vertical vibration sensitivity of the human body

18

1.2 Noise

Fig.1.15 propagation of sound

Impulse p⊿t

Momentum variation

c⊿t

Pre

ssure

p [

Pa]

Time t [s] Atmosphere

pressure

Particle velocity u

Air density

propagation of sound

in velocity c

ρc⊿tu

p = ρcu

Wavelength λ c =λf

19

1.2.1 Definition of noise level

Sound pressure ： ]N[ 2ｍp

Particle velocity of sound:

cppuW

cpu

2

]m/s[

Minimum human audible sound pressure

(Definition of 1000Hz): ao Pp

5102

Power for p0 ： Wo

Definition of noise level ：

]dB[)log(20)log(10)log(10 22 ooo ppppWWSPL

Sonic power per unit area:

SPL weighted the frequency characteristics A is “noise level A”.

and the unit is dB (A) ; decibel-A or Hon.

Pressure 10times=20dB

Power 100times =20dB

Pressure 2times =6dB

Pressure 1.4times =3dB

Power 2times =3dB

20

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10 12 14 16

PA=1×sin(ωｔ）

PA+PB=2×sin(ωt) , PA +6 dB

PB=1×sin(ωｔ）

PA+PB=0×sin(ωt) -2

-1.5

-1

-0.5

0

0.5

1

1.5

2

0 2 4 6 8 10 12 14 16

PA+PB=1.4×sin(ωt) , PA +3 dB

Fig.1.16 propagation of sound 1/2

21

80dB ＋ 80dB = 83dB

Fig.1.17 propagation of sound 2/2

22

1.2.2 Audible range of human and Automotive Noise

Frequency Hz

Sound

pre

ssure

dB

Minimum audible noise

Brake noise

Win

d n

ois

e

Bo

om

ing

no

ise

Bo

om

ing

no

ise

Bo

om

ing

no

ise

Engine noise

Tire noise

Gear noise Road noise

Minimum audible noise of common

Maximum audible noise

Fig.1.18 Human audible noise

23

Frequency Hz

Fig.1.19 Isopter curve of Fletcher-Munson

Sound p

ress

ure

d

B

24

Frequency Hz

Fig.1.20 A,B,C curve

25

1.2.3 Acoustic Isolation

Wt

WiTL log10

図１１　遮音壁の透過損失

0

20

40

60

80

100

120

140

0.1 1 10周波数　f　[kHz]

透過

損失

TL [

dB]

md

cf

2

2

1

dcf

2

dcf Double-walled

)2

log(20c

mTL

6)2

log(40 c

mTL

図14

Tra

nsm

issi

on

Loss

T

L [

dB

]

Frequency f/f0 [kHz]

入射 透過

Face density m [kg/m3]

d [m]

Wi Wt

入射 透過

Wi Wt

incident

incident Transmission

Transmission

Fig.1.21 Transmission loss

26

d

λ/2

λ/2 (half-wavelength) multiples Standing wave occurred

Incident Transmission

Fig.1.22 Standing Wave

27

高周波ほど厚いほど吸音する

図 1５

Frequency [Hz]

Density

Thickness

Aco

ust

ic a

bso

rpti

on c

oef

fici

ent

1.2.4 acoustic absorption Absorption ↑

↑

↓

↓ Absorption

Input

Transm

ission

Reflec

tion

acoustic absorption

coefficient＝

１－ Reflection /Input

＝(Absorption +Transmission)/Input

Fig.1.23 Acoustic absorption coefficient

28

• particles make a movement in the air between Fibers.

• thermal energy conversion by the loss of fluid resistance

•fluid loss is decrease near the

wall, as air particle velocity

will decrease.

Long wavelength λ needs a

thick layer of acoustical

absorption material.

Fig.1.24Effect of acoustic material

吸音層

λ/4

粒子速度

λ/4

In the high frequency,

acoustical equivalent

of the thick layer

Wall Absorption

material

Particle velocity

29

Frequency Hz

Mas

kin

g d

B

• that the frequency is higher than 400Hz is felt as a small sound by the pure tone of 400Hz.

• The decline level of sound is defined “masking” .

• longitudinal axis of the graph shows masking level.

1.2.5 Masking

図 1７ 純音による純音のマスキング Fig.1.25 Masking of pure tone by 400Hz pure tone

Temporal Masking

30 Fig.1.26 Temporal Masking

31

1.2.6 frequency modulation:

• Generate a beat tone by overlap

• frequency modulation 4Hz: 『fluctuation ;変動感』max

• frequency modulation70Hz：『rough deposits;ざらざら感』Max

• frequency modulation200Hz：flat/smooth sound; 平坦な音

32

1.2.6 The sound quality assessment

• A sense of quality is studied

with multi-factorial analysis .

• sound classification such as

“metal sound” , “light” etc.

shows characteristics of group

of sound.

• This axis representing the

property as a car sound.

Fig.1.27 coordinate space representing the sound quality

Comfort sense factor

Powerful sense factor Metal sense factor

Luxury sedan

Sport car

33

2. Performance/Functions and Components

Expected utility Vehicle

Vehicle

Performanc

e

Performance

/Functions

Component

z

y

x

・

・

・

c

b

a

53

52

51

・

・

・

3

2

1

34

Performance/Functions and Components

payl

oad

& e

ase o

flo

adin

g

com

fort

&eas

e o

fegr

ess

/in

gress

ope

rabi

lity

field

of

visi

on &

visi

bilit

y

bala

nce o

f ext

erior

aero

dynam

icchar

acte

rist

ics

engi

ne

perf

orm

ance&dr

iva

fuel econom

y &

em

issi

on c

ontr

ol

heat

resi

stan

tpe

rform

ance

brak

ing

perf

orm

ance

driv

ing

stab

ility

park

ing

perf

orm

ance

runnin

g th

rough

tpe

rform

ance

collisi

on s

afety

perf

orm

ance

ride

com

fort

vibr

atio

n&nois

e

air

condi

tionin

gpe

rform

ance

info

rmat

ion

perf

orm

ance

sound

perf

orm

ance

envi

ronm

ent

com

patibi

lity

mas

s&in

ert

iam

om

ent

relia

bilit

y& d

ura

bilit

y

eas

e o

f re

pair a

nd

mai

nte

nan

ce

recyc

labi

lity

produ

ctivi

ty&as

sem

bly

work

ability

cost

1 engine ◎ ○ ◎ ◎ ◎ ◎ ◎ ○ ○ ○ ○ ○ ○ ○2 air intake system ◎ ○ ○ ◎ ○ ○ ○ ○ ○ ○3 fuel gauge ◎ ◎ ○ ○ ○ ○ ○ ○ ○ ○ ○4 cooling system ◎ ○ ◎ ○ ○ ◎ ○ ○ ○ ○ ○ ○5 exhaust system ◎ ○ ◎ ◎ ○ ○ ○ ○ ○ ○ ○6 clutch ◎ ◎ ○ ○ ○ ○ ○ ○ ○7 transmission ◎ ◎ ○ ◎ ◎ ○ ○ ○ ○ ○ ○ ○8 mount of power train ○ ◎ ◎ ○ ○ ○ ○ ○ ○9 propeller shaft ○ ◎ ○ ○ ○ ○ ○ ○10 final drive ◎ ○ ◎ ○ ○ ○ ○ ○ ○11 axle shaft ◎ ○ ○ ○ ○ ○ ○12 drive shaft ◎ ○ ○ ○ ○ ○ ○ ○13 axle ○ ○ ○ ○ ○ ○ ○ ○14 brake system ◎ ○ ◎ ◎ ◎ ○ ○ ○ ○ ○ ○ ○15 parking brake ◎ ◎ ○ ○ ○ ○ ○ ○ ○ ○16 wheel ◎ ◎ ◎ ○ ○ ○ ○ ○ ○ ○ ○17 tire ○ ◎ ○ ◎ ◎ ◎ ○ ◎ ◎ ◎ ○ ○ ○ ○ ○ ○ ○18 steering system ◎ ◎ ◎ ○ ◎ ○ ○ ○ ○ ○ ○ ○19 front suspension ◎ ◎ ◎ ○ ◎ ◎ ○ ○ ○ ○ ○ ○ ○20 riar suspension ○ ◎ ◎ ○ ◎ ◎ ○ ○ ○ ○ ○ ○ ○21 manipulation system ◎ ◎ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○22 piping ◎ ○ ○ ○ ○ ○ ○ ○ ○ ○23 cable routing ◎ ○ ○ ○ ○ ○ ○ ○24 frame ◎ ◎ ◎ ◎ ◎ ○ ○ ○ ○ ○ ○ ○25 body structure ◎ ◎ ◎ ◎ ◎ ○ ◎ ◎ ◎ ◎ ◎ ◎ ○ ○ ○ ○ ○ ○ ○26 glass ◎ ◎ ◎ ◎ ○ ◎ ○ ○ ○ ○ ○ ○ ○27 door ◎ ◎ ◎ ◎ ○ ◎ ○ ○ ○ ○ ○ ○ ○ ○28 tailgate ◎ ◎ ◎ ◎ ◎ ○ ○ ○ ○ ○ ○ ○ ○29 hood ◎ ◎ ◎ ○ ◎ ○ ○ ○ ○ ○ ○ ○ ○30 bumper ◎ ◎ ◎ ○ ○ ○ ○ ○ ○ ○ ○31 exterior parts ○ ○ ○ ○ ○ ○ ○ ○ ○ ○32 seat ◎ ○ ◎ ◎ ◎ ○ ○ ○ ○ ○ ○ ○33 seat belt ○ ◎ ○ ○ ○ ○ ○ ○ ○34 passive safety device(air bag) ○ ◎ ○ ○ ○ ○ ○ ○ ○ ○35 trim ○ ○ ○ ○ ◎ ◎ ○ ○ ○ ○ ○ ○ ○36 sound isolation&acoustic material ◎ ◎ ○ ○ ○ ○ ○ ○37 instrument panel ◎ ◎ ○ ○ ○ ○ ○ ○ ○ ○38 air conditioner ○ ○ ◎ ◎ ◎ ○ ○ ○ ○ ○ ○39 defroster ◎ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○40 wiper ◎ ○ ◎ ○ ○ ○ ○ ○ ○ ○41 windshield washer ◎ ○ ○ ○ ○ ○ ○ ○42 rear view mirror(inside&outside) ◎ ◎ ○ ◎ ○ ○ ○ ○ ○ ○ ○43 audio&visual ○ ○ ○ ◎ ◎ ○ ○ ○ ○ ○ ○44 navigation ○ ◎ ○ ○ ◎ ○ ○ ○ ○ ○ ○45 lighting devices ◎ ○ ○ ○ ○ ○ ○ ○ ○46 alternator ○ ○ ○ ○ ○ ○ ○47 battery ○ ○ ○ ○ ○ ○ ○48 wiring harness ○ ○ ○ ○ ○ ○ ○ ○ ○49 layout of interior ◎ ◎ ◎ ◎ ◎ ◎ ○ ◎ ○ ○ ○ ○ ○ ○50 layout of engine room ◎ ◎ ○ ◎ ◎ ◎ ○ ○ ○ ○ ○ ○ ○51 latout of underfloor ◎ ◎ ○ ○ ◎ ◎ ○ ○ ○ ○ ○ ○ ○52 specification dimention,aerodynamic characteristics ◎ ◎ ◎ ○ ○ ○ ◎ ◎ ○ ○ ○ ○ ○ ○ ○ ○53 mass&inertia moment&center of gravity ◎ ○ ○ ◎ ◎ ◎ ◎ ○ ○ ○ ○ ○ ○ ○

auxilia

ry p

art

sla

yout

vehicle performance are represented with 26 items

Components are consolidated to 53 units

pow

er/

dri

ve t

rain

chassis

body

trim

35

○： link point of connection (Targeted value is established)

•Balancing a lot of targets

•Deterioration of Growth factor

(Circular reaction to increase weight

and cost)

↓

•Subject：

Noise and Vibration-Management

simulation system is necessary.

Table　1-1 Table of Noise and Vibration in passenger Vehicle

Idlin

g vi

brat

ion

Powe

r Hop

&Vibr

atio

n

Clut

ch ju

dder

Acce

lera

tion

shoc

k s

urge

Sim

my

Shak

e

Brak

e ju

dder

Engin

e no

ise

Gea

r nois

e

Drum

min

g

Boom

ing　

noise

Road

　noi

se

Win

d　no

ise

Unbalance of engine ○ ○ ○Sycle variation of engine torque ○ ○ ○ ○ ○Sycle variation of engine force ○ ○Trangent torque of engine ○ ○ ○ ○Combustion noise ○Exhaust noise ○ ○Clutch ○ ○Rotation of coupling and shaft ○ ○ ○Tire uniformity ○ ○ ○Tire unbalance ○ ○Gear ○ ○Road surface ○ ○Brake ○Turbulance of air ○Power unit ○ ○ ○ ○ ○ ○ ○ ○Flywheel ○ ○ ○Clutch ○ ○ ○Transmission ○ ○ ○Propeller shaft ○ ○ ○Coupling ○ ○ ○ ○ ○Drive shaft ○ ○ ○Differential gear ○ ○ ○Axle shaft ○ ○Steering wheel ○ ○ ○ ○Steering system ○ ○Steering column ○ ○ ○Suspension ○ ○ ○ ○ ○Wheel ○Tire ○ ○ ○ ○ ○ ○ ○ ○Engine mounting ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○Power train mounting ○ ○ ○ ○ ○ ○ ○ ○ ○Body structure ○ ○ ○ ○ ○ ○ ○ ○Interior & exterior ○ ○ ○ ○ ○ ○ ○Sound insulation material ○ ○ ○ ○ ○Cavity ○ ○ ○

Com

pone

ntｓ

spec

ifica

tion

Exci

tatio

n so

urce

2. Automotive Vibration and Noise 2.1 Noise and Vibration-Management table

comparison for

performance items

and components

36

vibration source and transmission system of noise and vibration

Input from the road 0～500Hz

Engine rotation 20～300Hz

P/ Train shaft rotation 0～200Hz

Tire rotation 0～100Hz

Engage gear 0～5000Hz

Transient fluctuation 0～20Hz

Brake power fluctuation 0～30Hz

････ Sound vibrating force・・・・・

Engine noise ～10kHz

Disruption in air flow ～4000Hz

Cooling fan noise ～3000Hz

Tire noise ～3000Hz

Tire

Frame

Body

Engine

Transmission

Mounting system

Drive Shaft

Exhaust system

Suspension

Brake

Steering

Sheet

Body vibration

The vibration of

operation system

Vibration of

Rearview mirror

----------------

Sound pressure of

interior

Tone

Vehicle

exterior noise

Vibratory Force source Vibration system,

Transmission system Evaluation

partial

Vibration

Noise

Vibration

37

2.2 Representative examples of automotive noise and vibration

Fig.2.1 Idle vibration

15-a

15-b

15-c

15-d d) Vibration of body, steering wheel and seat

a) Roll Vibration of engine

b) Vibration of body

c) Vibration of exhaust system

38

Engine

Mass

ｍ＞１００ｋｇ

x” mＰ

The piston vibrating force

(Inertia force)

mＰx”

The piston vibrating force is increasing

with increasing rotation speed.

2000cc class 4 cylinders

About 20 kN !! (at 6000 rpm)

If 100kg engine units

200m/s2 (20G)

Fig.2.2 Force and vibration of 4 cylinders engine

39

Minimization of transmitted force of engine

Ⅰ. lower set Eigen value √ k / m ( rigid engine Natural frequency).

* k lower → but increase in low-frequency vibration of the engine

* m increase → but increasing weight effect to other adverse

Ft ／ F0 : Minimization of Force Transmissibility

Ⅱ. lower setting of Damper C * C lower → but engine vibration near the natural frequency is increased

F0sinωｔ mass

m

x

spring k [N/m]

damper c [Ns/m]

Ft

40

But engine vibration was heavy at 600 rpm idle rotation.

(Main vibration of 4-cylinder engine is second orders of rotation.

vibration frequency is f = 20Hz at 600rpm. )

Hzff

ff

f147.0

22 0

00

Necessary conditions to set vibration transmission rate less than

1 are following.

①The natural frequency of rigid engine vibration

： lower than f0 ＝10Hz (Low spring mounting)

② engine mounting insulator : lower damping ratio

New Challenges ！ The failure of

low natural frequency

engine natural frequency was reduced to 20 Hz to minimize

“transmitted force of engine”.

0.1

1

10

0 1 2 3 4β =ω ／ω 0

τ=F

t／F0

ζ =0.05

ζ =0.1

ζ =0.2

ζ =0.4

ζ =0.8

41

Exciting force

20Hz↓

↑ Natural

frequancy

14Hz

↑ Natural

frequancy

10Hz

↑ Natural

frequancy

20Hz

F0sinωｔ mass

m

x

spring k [N/m]

damper c

[Ns/m]

Ft

Force transmissibility is reduced with

β increase and ζ decrease

Fig.2.3 Force Transmissibility of engine

42 Fig.2.4 Car shake

Excitation Force

① tire uniformity (Heterogeneity) ② Eccentricity of Tire and wheel ③ Unbalance of tire (centrifugal force) ④ Displacement input from the road surface irregularity

about 10 Hz oscillation

Mounting (spring),

engine (mass)

about 10 Hz oscillation of

the steering wheel and seats

43

Low damping rubber

Liquid chamber1

0.1

1

10

0 1 2 3 4β =ω ／ω 0

τ=F

t／F0

ζ =0.05

ζ =0.1

ζ =0.2

ζ =0.4

ζ =0.8

Liquid chamber2

orifice

diaphragm

air

Fig.2.5 solution by engine mounting

44

• Combustion piston pressure tapping

• Bending the crankshaft

• Cylinder block of skirt is

deformed.

• After the entire combustion

damping vibration of engine

Percussion

instrument

Fig.2.6 Mechanism of combustion engine sound generating

45

• Combustion characteristics of sound is damping vibration happen

continuously.

• Like the temple bell hit continuously.

Fig.2.7 combustion engine noise

(from consideration of crank shaft bearing vibration)

46

Fig.2.8 transmission path to a car of engine noise

Mechanical nose

Combustion noise Exhaust nose

Air inlet noise

Transmission

by Vibration

Transmission

by Noise Fan noise

47 Fig.2.9 mechanism generating Ingressive/Exhaust sound

• wind

instrument

Blow-down

immediately after

the opening valve

extrusion

by Piston

Crank angle

Reflection Damping Reflection Radiation

tube Resonance

Engine speed rpm 騒音

レベ

ル d

B

Nois

e le

vel

dB

Exhau

st r

unoff

48

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-1

-0.5

0

0.5

1Time Domain

Time [s]

leve

l

100

101

102

-400

-350

-300

-250

-200

-150

-100

-50

0Freq Domain

Frequency [Hz]

Pow

er S

pect

rum

[dB

]

Fig.2.10 FFT of sine curve

49

0 2 4 6 8 10 12 14 16 18 20-40

-20

0

20

40

時間　ｔ　(s)変

位加

振　

ｘ0 (

m)

0 2 4 6 8 10 12 14 16 18 20-3

-2

-1

0

1

2

3

時間　ｔ　(s)

応答

変位

振幅

　ｘ

(m)

10-1

100

101

-350

-300

-250

-200

-150

-100

-50

0

50変位加振力のPower Spectum

Frequency [Hz]

Pow

er S

pect

um [

dB]

Fig.2.11 FFT of sine curve with Blow-down

50

3. Analysis technology and Embodiments

systems Method Software Application

Finite Element Method NASTRANADENAABAQUS,MARC

Vibration mode analysisacoustic vibration analysisnonlineer analysis

Boundary element method SYSNOISE

Sound geometric method RAYNOISE Vehicle interior sound field analysis

structure mechanism

Marti-Mody-Dynamics ADAMS,DADS

Stability AnalysisRide confort analysisEngine excitation analysisDriveability analysis

Integrated Systems

Energy methodBond Graph

Dymola power analysis

controlModern control theoryAdaptive control theory

MATLAB/Simlink Control Analysis

Statistical energy analysis method

mechanics

AutoSAE SEAMSEADS

High frequency vibration analysisHigh frequency vibration analysis

acoustic

51 Fig.3.1 Finite Element Model

FIAT ：IMAC2005-01-2392 より

The Effect of Spot Weld Failure of Dynamic Vehicle

Performance ;LMS International ;IMAC2005より

52

Fig.3.2 Sound field model

Frequency Hz

Simulation result

simulation

Experiment Elements

Nodes

Vehicle interior sound field model

trunk Vehicle compartment

53

m1

k１ c１

X１

m２

k2 c2

X２ 2nd bending

mode

Example of low-frequency vibration of body (from consideration of physical Model)

1stbending

mode

Analytical Model

（physical Model）

(2 nodes)

(3 nodes)

Fig.3.3 low frequency vibration of car body

54

Car_3D_step

Fig.3.4 visual demonstration vibration of car body

55

全開加速 定常走行

10m 10m

7.5

m

マイクロホン位置

地上1.2m

50 km/h

2nd or 3rd

Gear

図27 加速走行騒音の試験法（日本）

ISO試験路面

Full throttle acceleration Constant speed

Microphone position

Height 1.2m

ISO read surface

4. Vehicle and Noise (from the standpoint of pollution)

Fig.4.1 Acceleration pass-by noise test (Japan regulation)

56

4.1 The main source of vehicle exterior noise

•Most of the noise source is

approaching saturation point as

the result of inputting effective

measures.

•The engine has been

significantly improved, but

further reduction is needed.

•Tire noise that haves tradeoffs

with steering and stability, is

needed more reduction.

•Exhaust noise is often

increased by the illegal

modifications that should be

checked severely for society.

•To create a society of silence,

further noise reduction

technology is expected.

図２４　加速走行騒音への主要音源の寄与率 %

エンジン

タイヤ

排気

冷却ﾌｧﾝ

その他

図28

Engine

Tire

Exhaust

Cooling Fan

Others

Fig.4.2contribution percentage rate of

the major noise source

(Acceleration pass-by noise test )