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NOISE POLLUTION
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Noise
Undesirable or
unwanted
sound
Impacts
,
Stress
ys ca
an
psyc o og ca
amage
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Noise Pollution Causes
Noise From
Automobile
‐‐‐‐‐‐‐‐very
high
Railway Stations
ircrafts
Industrial Noise Construction Equipment
Household Equipment
Other Causes
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Road Traffic Noise
• Traffic is the biggest source of noise pollution in
to ays t mes, espec a y n ur an areas.
• In the past few years the number of automobile
vehicles has increased manifold.
• us, ra c pro ems crea e y ese ve c es s an
important source of noise pollution.
• The sound produced by the exhaust systems of trucks,
, , , . .
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Noise Generation
Road Traffic
noise
is
the
aggregation
of
noise from individual vehicles in the traffic stream.
Th r
r
v n
rin i l
f r
n
which the generation of road traffic noise de ends:
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….CONTINUED….
• Traffic volume
•
• Traffic composition
• oa gra en
• Road pavement surface type and texture
• Driving conditions
• Individual vehicle noise
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7
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8http://www.nonoise.org/library/highway/traffic/traffic.h
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9http://www.nonoise.org/library/highway/traffic/traffic.h
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• The
engine• The transmission
• The braking system
• The interaction
of
tyres and
road
pavement
surface
• Body, tray and load rattles
• Movement of air around the vehicle
• Horn
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Noise From Engine
There could be several reasons that could be causing a
.
engine is not being completely lubricated.
s wou e cause y e er e eng ne ac ng o , or
the engine not having sufficient oil pressure.
Engine Noise Remedy
..Use professional quality oil filters.
.. By using Spark Plug Threads
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D namat under the hood
Dynamat - Expensive material but very very effective,
most eo le use this material for car audio because it
works really good to improve sound and stop vibrations and
rattling.
Dynamat -will protect the hood's paint finish from engine
heat to the engine as well.
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Noise reduction in two wheeler gears
Gear noise can be attributed to several reasons such as
gear design parameters, gear material used etc.
Owing to design, spur gears during operation produce
noise
A change in gear design to helical would reduce the noise,but at in the cost of an increase in friction as in operation it
produces an axial thrust.
A more economic and effective way of noise reduction ingears would be to go in for a material, which has good
significantly.
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cont….
A new member of the cast iron family, Austempered Ductile Iron
(ADI), is a heat treated Spheroidal Graphite Iron(SGI).
The microstructure exhibits ausferritic structure with a high
volume of carbon-enriched austenite and nodular graphite.
This offers the gear designer a combination of manufacturing
flexibil ity, high strength, toughness, low weight, excellent fatigue
strength and wear resistance.
These properties are present along with good damping capacity
and machinability.
. ADI thus developed has been evaluated for mechanical
properties like tensile strength, impact strength etc.,..
ADI possess significant damping properties and helps in gear
noise reduction.
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TYRE NOISE
THE
TYRE
HITTING
THE
GROUND…
THE VIBRATION OF THE AIR THROUGH THE
THREAD
PATTERN…
THE VIBRATION PASSING THROUGH THE TYRE..
NOISE DEPENDS ON THE ROAD SURFACE AND ……
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The noise which is radiated from the tyre surface is produced by several mechanisms, including the vibration of the tyre
,
road surface
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Surface texture bum s and di s
Avoid (flatten) texture that repeats itself at intervals of 1 inch or larger.
. ., ,
fine texture (that is on the scale of 1/8 to 1/4 inch) should be provided.
Texture should be “negatively” oriented, meaning that any “deep” texture
should point down (e.g., grooves) rather than up (e.g., fins).
Joints, ,
also annoyance.
-
Faulted joints should be avoided by providing adequate load transfer.
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The exhaust system of an internal combustion engine has anumber of functions, one of which is to reduce the noise of the
atmosphere
The three basic exhaust noise mechanisms are:• - s s e no se ra a e rom e uc as opensinto the atmosphere
• -mounting system to the surrounding structure.
• - the exhaust system (pipes, catalysts and silencers).
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Noise POSSIBLE PROBLEM SOLUTIONBACKFIRING S Incorrect ignition timing, faulty ignition or
leaking valves
Have ignition and/or valves checked.
CLATTER FROM ENGINE Insufficient engine oil.Worn or badly adjusted valves.
Add oil.Refer to a mechanic
WHINING OR CHATTERING FROMENGINE
Incorrectly tensioned camshaft drive belt. Refer to a mechanic as soon as possible
RATTLE WHEN ACCELERATING Wrong grade of fuel;
engine overheating;engine needs decoke
incorrect ignition timing;i nition s stem fault.
Use higher grade of fuel;
Refer to a mechanic.
KNOCKING FROM ENGINE WHICHINCREASES WITH ENGINE SPEED
Worn camshaft or cam followers. Refer to a mechanic as soon as possible.
SCREECH UNDER ACCELERATION Slipping auxiliary drive belt/fan belt. Check/adjust belt or have a replacementfitted.
SCREECH WHEN STEERING Power steering belt slipping. Check/adjust belt.
STEERING
. .
ROAR OR RASP UNDER ACCELERATION
Blown exhaust. Have exhaust checked.
SQUEAL OR GROAN WHEN BRAKING Worn or defective brake com onents. Refer to a mechanic.
HISS FROM ENGINE Leak from coolant or air/vacuum hoses. Refer to a mechanic.
CLICKING FROM WHEELS Loose hubcap; Tighten hubcap;
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NOISE (vs) SPEED
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How To Measure
The
Noise….???
dB:
What
is
a
decibel?
Intensity of a single sound is measured on a relative of
logarithmic
scale Uses a unit ca e a e B or su unit – eci e B,
1/10 of a bel)
,
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S.NO Type of vehicle Noise Limits from 1st
Date of implementation
January, 2003,
dB(A)
1 Two wheeler
Displacement upto 80
cm3 75
than 80 cm3 but upto 175 cm3
Displacement more
80 Ist January,2003
than 175 cm3
2 Three wheeler sp acemen up o 175
cm3 Displacement more than 17 cm
77
80 Ist January,2003
3 Passenger
car 75 Ist January,2003
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e eve o ommon oun s
Source Noise Level (dB) Effect
arr er ec e opera on, a r ra s ren a n u y ou
Jet takeoff at 200 feet 130
Disco, thunderclap 120 Maximum Vocal Effort
Auto Horn at 3 feet 110
Garbage Truck 100 , , -
Alarm Clock at 2 feet, hair dryer 80 Annoying
Noise restaurant, freeway traffic, persons voice at 3 feet 70 telephone use difficult
Air conditioning unit at 20 feet 60 Intrusive
Light auto traffic at 100 feet 50 quiet
, ,
Library, soft whisper at 15 feet 30 very quiet10 Sound just audible
0 Hearing begins
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um er o peop e annoye
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….CONTINUED….
Significant
variability
in
noises
from
transportation sources
A
‐ weighted
noise
level
(equivalent
“irritation”
level – has to do with mix of frequencies)
DNL (day/night
level
– weights
night
time
noises)
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Noise Propagation Noise is generated at source and spreads spherically away
from source
n ens y m n s es w s ance
Losses also occur from sound energy being dissipated as
sound is
transferred
b
air
articles
Bending and diffraction occurs as sound waves encounter natural and manufactured solid objects
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Road Traffic Noise propagation
Propagation
is
the
wave
process
where
There
are
a
number
of
factors
which
n uence e propaga on o roa traffic as follows:
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….CONTINUED….
Road
corridor
cross
sectionDistance between source and reception po nt
Type
of
intervening
ground
cover
between
. , water or concrete)
obstructions
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Control of Transportation Noise
Federal ‐‐
Noise
control
act
of
1972 Reco nized noise as a ma or de rader of urban
living
Encourage use
of
noise
standards
State and local governments
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Noise Control Strategies
Source
controls Vehicle control devices – maintenance, traffic
an ig way esign contro s
Path
controls Sound barriers that reflect and diffuse noise
Buffer zones
Receiver‐si e
contro s
Insulation
31
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Traffic Control Measures
Prohibit
trucks
ruc rou es
Prohibit
daytime
(or
night
‐time)
use
Traffic signal timing..
pee
imits
32
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SOURCES OF ENGINE NOISEEngine noise is the sum of two elements:1. com ust on no se
2. mechanical noise.
• mechanical noise dominates the engine noise produced by
spark ignition (gasoline) engines;
• combustion noise is a more significant contributor to the engine
noise produced by compression ignition (diesel) engines.
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Combustion noise.
applied to the structure of the engine, causing vibration to occurwhich is then radiated as noise
2.The gas forces in each cylinder vary during the working
cycle of the engine (two or four stroke). They are highestduring the combustion period where the cylinder pressure
rising quickly.
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Mechanical noise1. The crank mechanism(pistons,connecting rods,crankshaft,
bearings) experiences externally applied forces due to gas
forces and internally generated forces
2. Around TDC there is a rapid reversal in side force produced
by the slider-crank mechanism. This produces piston slap as the p s on mpac s on e cy n er- ner. s on s ap s norma y e
dominant source of mechanical noise in the diesel engine.
3. Piston slap noise increases with engine speed. It also increaseswith turbo charging. It is mostly controlled by reducing
-
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Mechanical noise1. In gasoline engines, piston/liner clearances are relatively
small, and mechanical noise tends to be dominated by impactsin the crankshaft bearin s made throu h the oil film.
2. At low engine speeds these are magnified by increasing
. ,
crank mechanism dominate so there is little load dependency.
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Mechanical noiseOther sources of mechanical noise include:
• timing drive;• valve train
• fuel injection equipment.
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Measurement of engine noise• ,
acoustically treated test cell that replicates the outdoor environment(commonly a semi-anechoic cell with large sound absorbing wedges
on e wa s an ce ng an a a concre e oor .
• The engine is either tested in its bare state (with just enough
equipment to run – pumps and manifolds are fitted but theintake/exhaust noise is ducted away) or in its fully equipped state
(everything fitted including ancillaries and sometimes full intake and
.
• The engine is tested at the maximum power point, at the maximumtorque point, at the point of maximum speed but minimum load and
a so a e.
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Measurement of engine noise• oun pressure eve s are measure a ree pos ons or eac
engine operating condition. These are at 1.0m from the longitudinalcentres of the vertical planes forming the smallest rectangular box
which completely encloses the bare engine. The measuring points
are on both sides and in front of the engine at the height of the
• The noise levels at the three specified locations are reported.
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Measurement of engine noise‘ ’ -
same height and distance from the box as the specified locations. Ifthe survey reveals readings more than 3 dB
above the highest reading at the specified locations, then the
survey readings are also reported.
• The reported results should be the averaged results of two or
more test results within 2 dB of each other.
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Engine noise control1. The period between the start of the injection and ignition, known
as ignition delay period has an important Learning on combustion
noise. Turbo charging, by which air is forced into the intake at
,
period and a more gradual rise in pressure with, consequently, lower
noise generation.
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Engine noise control• stiffen structures to ush resonant fre uencies above the
highest forcing frequency;
• encapsulate noise sources with massive panels;
• add damping where resonances occur.
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Engine noise control• Oil pan – the use of an isolating gasket between the oil pan andt e cran case. e a opt on o structura a um n um o pans to
replace the traditional pressed steel components has made oilan noise more si nificant in s ite of im rovements to the
crankcase to reduce its noise radiation.
• –
• Fuel injection equipment – the adoption of common rail
systems an un t n ector systems w c are more compact an
quieter have brought about significant improvements
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Engine noise control• Intake s stem – the avoidance of lar e lanar surfaces on intake
components can reduce noise emissions along with general stiffening
of the structures.
• Noise shields – well-damped, isolated engine covers can reduce
noise radiated by the engine structure.
• Engine bay enclosures – engines may be effectively enclosed within
their en ine ba in the vehicle thus enca sulatin the noise sources.
Problems with ventilation and cooling are common.
•
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Engine noise control
- ,use this material for car audio because it works really good to
improve sound and stop vibrations and rattling. To help this
re uce car eng ne no se ras ca y you wou wan o app y s
material to the bottom of the car hood and the firewall area of
the vehicle. You could also apply this material to the doors or
other areas of the vehicle. Dynamat will protect the hood's paint
finish from engine heat to the engine as well.
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Engine noise control1. Engine noise through the radio - From revving the engine or
just constant noise. Engine noise through your speakers is
- .
thing you could do is take all the grounding cables in vehicle
and put them one spot that is groundable2. Because of the difficulty, there is an additional option; buying
a Ground Loop Isolator which will eliminate the electrical
noise and hum caused b round loo s. This noise could also
be caused by running audio cables close together in thevehicle and components such as an amp, satellite radio, mp3
p ayer.
TRANSMISSION NOISE INCLUDES
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TRANSMISSION NOISE INCLUDES
GEAR BOX NOISE
CLUTCH NOISE
PROPELLOR SHAFT
NOISE
BEARINGS NOISE
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GEAR BOX
NOISE
S ur ear roduce more noise
Helical ears roduce less noise
S nchromesh
ear box
roduce
ver
less
noise
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impetus
for
the
most
noise
within
a
gear
box.Noise level and frequency are affected by:
Type of gear teeth
Gear tooth geometry
u r ca on
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Gear Tooth Selection
The more constant and uniform the contact, the lower the friction forces which cause noise
This is true for all types of gear designs: spur, e ical, spiral bevel or straight bevel.
Gear Tooth Geometry
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Gear Tooth Geometry
For example, increasing the height of a tooth to achieve reater overla or mesh can actuall reduce the ear's
ability to transmit load.
, near the tip of the gear tooth, can ease an incoming tooth
into
contact
with
other
teeth
This involves reducing the material on either end of a gear tooth to produce a more oval tooth profile.
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Smooth Finished
Surfaces
Normally, the
finer
the
finish,
the
lower
the
noise
level.
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Thicker Lubricants
While higher
viscosity
oils
and
greases
can
cut
down
on
noise
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Clutch noise
Do clutch noise is more
Friction clutch noise is less
Torque converters noise will be very less
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57
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Definition
Devices which are used to reduce the sound levels
58
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Classification
Dissipative type
Combination type
Spark arresting type
Catalytic silencer
59
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Dissipative Type
Uses sound absorbing materials
Take energy out of acoustic motion in the
wave as it propagates through the silencer
60
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61
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Reflects sound wave back to the source and prevent sound from
being transmitted along the pipe
Commonly used in automobile applications
62
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Expansion chamber type
change in cross sectional area in the pipe.
Do not have the high attenuation of the Hemholtz resonator, but have
a broadband frequency characteristic
Their performance also deteriorates at higher frequencies when the
Some expansion chamber muffler systems are also packed with sound
absorbing material which helps to improve the high frequency
a enua on.
64
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65
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66
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67
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Silencer selection factors
Acoustical performance(insertion losses)
Aerodynamic performance(maximum acceptable pressure drop)
Mechanical performance
Material selection
Durability
Little maintenance
12
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Design factors
nser on osses
RestrictionVolume
Weight
Durability
Cost
Ease of manufacture
Styling
Tonal quality
69
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ome um ru es or es gn
Volume – 5-10 times en ine swe t volume
Tailpipe length – less than 500mm
>500Hz noise control – pack silencers with porous
materials such as basalt or glass wool
70
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71
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Definitions
Noise
Noise is
defined
as
unwanted
sound
transmitted through air or another medium
Sound
It is defined as any pressure variation
(in air, water or some other medium) that
the human ear can detect
Sound Level Comparisons
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Measuring of
noise
dB: What is a decibel?
• The decibel (dB) is used to measure sound level..
• The dB is a logarithmic unit used to describe a ratio., The ratio may be power, sound pressure, voltage or
.,
to the
phon
and
the
sone (units
related
to
loudness).
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Causes of
noise
pollution
Traffic (Automobile)
Railway Stations
ircrafts
Industrial Noise
Construction Equipment
Household Equipment
Other Causes
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Definition of
traffic
noise
Road traffic noise is what you hear from driver's
vehicles, planes,
trains
and
buses
during
the
Examples of road traffic noiseSounds of engines speeding up,
horns blowing,
potholes being
hit
or
even
trucks
with
heavy
moving freight making lots of noise
Road Traffic Noise
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Traffic is the biggest source of noise pollution in
to ays t mes, espec a y n ur an areas.
In the past few years the number of automobile
vehicles has increased manifold.
us,
ra c pro ems
crea e
y
ese
ve c es
s an
important source of noise pollution.
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Sources of traffic noise in highways:
Automobiles
Buses
Motorcycles
Medium & Heavy Trucks
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u
sources o
no se
Tire Noise
Important for
autos
May be important for trucks
Tir ‐
P v m n
in r i nExhaust Noise
Low‐frequency
“rumble”
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Reasons for Traffic Congestion
Increase in car ownershipIncreased
commutin
Car ownership since 1920
YEAR NO.
OF
CARS
MILLIONS1920 O.51940 2.519 0 11
1980 191 0 21
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Problems caused by Commuting
Traffic Congestion
Air pollution
Noise pollution
Visual pollution
Parking problems
Destruction of houses
Increased risk of accidents
Factors Influencing of traffic Noise
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Generation • Road Traffic noise is the aggregation of noise from
v v .
• There
are
seven
principle
factors
upon
which
the
eneration of road traffic noise de ends:
1. Traffic volume
2. Average traffic speed
3. Traffic composition
4. Road gradient
5. oa pavemen sur ace ype an ex ure
6. Driving conditions
.
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Traffic Noise
Depends on vehicle mix
ou as
One heavy truck at 55 mph sounds as loud as
28 cars at 55 mph
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• De ends on vehicle s eed
– Tire/pavement noise dominates above 30 mph
Traffic at 65 mph sounds 2x as loud as
traffic at 30 mph
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Traffic Noise• Depends on amount of traffic
• Double
traffic
volume
=
increase
noise
by
3
dBA
+
= +3 dBA
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Tra c No se:
Trave
Patterns
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Solutions to Traffic problems
Widening roads
Bypasses
‐ inner ring roads
‐ outer ring roads
Urban Motorways
Bus lanes
Improving public transport
one way streets
Increase cost o car par ing
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Widening roads
B
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Bypasses
BournemouthRoad
High Street
Shrubbs Hill Road
t t
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one way streets
MDT N i P li
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MDT Noise PolicyMDT will consider installing noise berms or walls to
mitigate traffic
noise
IF:
6 noise re uction can e ac ieve
Affected landowners generally support mitigation
osts meet
a
ost‐
ect ve
n ex
Can be safely and reasonably built & maintained
N i B i
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Noise Barriers
Must block line of sight to vehicles on road
Will REDUCE
traffic
noise,
not
ELIMINATE
it
N i B i
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Noise Barriers
• REDUCE Noise, do not ELIMINATE
Noise
• Feasibility – safety, engineering factors, effectiveness
o wa
• Reasonableness ‐ overall benefits of abatement, public in ut.
• Mitigation cannot
protect
2
nd
floor• Decision to provide noise abatement made ONCE.
Mitigation Barriers
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Mitigation - Barriers
Mitigation Berms
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Mitigation - Berms
Mitigation Berm/wall
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Mitigation – Berm/wall
Mitigation Wall
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Mitigation – Wall
Noise Propagation
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Noise Propagation
Noise is generated at source and spreads spherically away
from source
n ens y m n s es w s ance
Losses also occur from sound energy being dissipated as sound is transferred b air articles
Bending and diffraction occurs as sound waves encounter natural and manufactured solid objects
Examples of road traffic noise
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Examples of
road
traffic
noise.
Road traffic noise is what you hear from driver's
vehicles, planes,
trains
and
buses
during
the
. , horns blowing, potholes being hit or even trucks with heav movin frei ht makin lots of noise are all examples of road traffic noise.
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The engine
The transmission
The braking system
The interaction of tyres and road pavement surface
Body, tray
and
load
rattles
Movement of air around the vehicle
Horn
NOISE REDUCTION TECHNIQUES
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NOISE REDUCTION
TECHNIQUES
Noise Reduction
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Noise Reduction
T ere is an increase sensitivity towar noise, rom a personal standpoint and a societal standpoint.
From front
and
side
windshields,
to
tire
wells
and
the
, unexplored when it comes to finding new ways to ensure a quieter driving experience.
There are increasin links between noise and vibration and at gue
e ort
are
ma e
n t e
c aracter st cs
n t e
development of the vehicle to minimize the noise and vibration harshness.
' vibration control components that are intended to reduce both
vibration
and
the
noises
created
by
the
vibration
within the vehicle.
Cont…
Cooper Standard's goal,is to isolate the engine from the restf th hi l
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p
g
g of the vehicle.
. as a solution for quieting the passenger compartment.
Their main
aim
is
not
trying
to
absorb
noise
once
it's
inside
, Carcoustics offers acoustics throughout the entire vehicle,
including the engine compartment, the interior and the
.Exploring the wheel wells and the body board for
additional noise reduction within the passenger
At
the
wheel
well,
Carcoustics has
added
an
acoustical
feature to
the
wheelhouse
liner.
‐ . .
systems
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systems
in the U.S. you have more or less injection molded, non‐
acoustical wheel
house
liners.
n urope, a same w ee ouse ner, an s o Carcoustics, adds acoustical features that reduce road tire noise, water spray noise in rainy weather and also reduces
noise from
stones
and
other
debris
coming
up.
Carcoustics acoustical wheel well is being used in the U.S .
Dashboard vents
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Dashboard vents
vents are the loudest points in an automobile
Carcoustics produced absorption
function
on
the
way
e ween e ven an e n er or o e ve c e o preven the noise from entering the vehicle
Glass
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Glasslaminate glass as one of the major trends in noise reduction.
swap
out
the
side
glass,
change
the
windshield
and
get
six
decibels of
noise
reduction.
Buick Rainier, Lincoln Navigator, Lincoln Aviator and the ultra luxury packaged Lexus LS430 all offer laminated glass
chan e from tem ered to laminated lass, ou et a significant
reduction
in
noise
because
in
the
past,
the
windshield was always the weakest link of where the sound was pouring into the interior.
An added benefit to laminated glass is weight reduction.
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Cont…
Solutia
Inc
offered
laminated
glass
product
called
VancevaQuiet's which has weight reduction capabilities.
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Dow Automotive offers a variet of roducts and services that target interior noise reduction. New to the U.S. this
year is the company's BetaMate, an adhesive that has been used
for
body
stiffness
improvements
and
stiffness
ura y w c equa es o v ra on re uc on.North America company LMS International provides the
software tools needed to make noise and vibration
possible. company's noise and vibration tools are
oun ua y,
Sysnoise and
LMS Test.Lab
Cont…
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Cont…LMS Sound Quality helps to subjectively identify, isolate
and rank the individual sounds that comprise a troublesome
noise.
Sysnoise predicts sound waves and the structural vibration induced by fluid loading effects onto a structure. The
pressure and radiated sound power, acoustic velocities and intensities, contributions of panel groups to the sound,
‐, , modes and structural deflections.
LMS Test.Lab is a dedicated measurement solution for .
Cont…
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Cont…In Porsche 944 engine The engine noise level was lowered
by primary
measures,
by
modification
of
the
solid
‐born
, neutralization. Particularly efficient were modifications to the crank gear, crankcase, valve gear, oil sump, intake
mani o , a ternator,
an
toot e
e t
rive
‐ ‐
Component Development
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Component Development
New blow moulding technology to reduce same level of
noise
reduction
but
lighter
in
weight.
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ENCAPSULATION
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Acoustic absorbers attached to the parts where the noise is
to
be
absorbed
is
called
encapsulation
EXAMPLE: Acoustic absorbers are applied to the hood, the bulkhead, the sides of the front beams and an under shield.
The encapsulation of the engine compartment arises from the need to reduce exterior noise
TRENDS
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Today, under shields are partially covered by an acoustic
material
or
made
of
an
intrinsically
absorbing
and
at
the
‐ .
Another trend is en ine‐mounted acoustic insulation components
on
the
oil
pan
and
in
the
area
around
the
fuel
injectors.
CONFLICTS
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A challenge for materials in contact with the engine is that
they
are
exposed
to
1. Strong vibrations,
.
3. Aggressive chemicals
4. Interfacing the shields with a very complex geometrical environment.
CONFLICTS
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5. Higher injection pressure,
6. Direct petro injection,
.
ADDED ADVANTAGE
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Reducing both fuel consumption and exterior noise
E icient encapsu ation can provi e a re uction in CO2 emissions by 2.5 g/km in the New European Driving Cycle (NEDC).
Underbody panelling can make a significant contribution towards reducing drag
NISSAN INFINITI
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NISSAN INFINITI
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The most recent study conducted
petrol engine shows that body-
mounted engine encapsulation can
reduce power train noise by 5 dB
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ENCAPSULATION WITH
RESPECT
TO
TEMPERATURE
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ENCAPSULATION WITH RESPECT TO
TEMPERATURE
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7 mm thick encapsulation covering 80 % of the
area is equivalent
to
50
mm
thick encapsulation
cover ng on y 0 ,
Therefore, the first priority in the development
o
an encapsu a on
s
e
g es
poss e
egree of area coverage rather than the choice of highly
.
NOISE REDUCION IN CI ENGINE
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Equipping parts of the engine air‐intake system with
porous
acoustic
materials
integrated
into
a
double‐
v v exterior noise quality of a diesel vehicle
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MATERIAL In 2007, a system of engine‐mounted parts
weighing less than 2.5 kg was presented . The
system provided
reductions
in
radiated
noise
in
the
engine test bench of 3 to 4 dB.
NEEDS
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combination of material optimisation,
o y ‐mounte an
‐
will be needed to achieve the le al re uirements for significant noise reduction
‐
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Body ‐mounted encapsulation is made of
components originating
from
acoustic
treatment:
The bonnet absorber,
Outer bulkhead and
Under‐engine
shield.
Vertical elements along the front beams form a tightly enclosed engine compartment
‐
ENCAPSULATIONl ll d h
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Electrically actuated shutters or
Other appropriate front closing elements
Limit heat and noise leakage through the radiator. The system must ensure an efficient flow of air through the radiator for optimum engine coolin durin drivin .
vibrations and operating temperatures are lower for body ‐mounted , .
BARRIERS IN
TAEE
ff d l f h l
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cost‐effective development of the sealing system
pass‐throughs for the steering column, drive shafts, cables and other interfaces need to be integrated.
ENGINE MOUNTED
ENCAPSULATION
E i d l i i ll b i fi d
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Engine‐mounted encapsulation is smaller but is fixed
to
surfaces
that
are
usually
hot
and
exposed
to
more
v y . materials with higher temperature resistance
THERMAL SAFETY
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SHELL DESIGN
R l l d th b t b b b i l
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Replace several covers and the bonnet absorber by a single element, thus allowing a significant weight reduction.
The construction comprises a lower and an upper shellmade of function‐s ecific, structurall and acousticall
optimised composite materials
ADDED ADVANTAGE
The double shell design efficiently combines the following:
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The double‐shell design efficiently combines the following:
1. high
noise
absorption 2. ig part sti ness
3. heat insulation
.
inlet
5. integration of pedestrian protection absorbers, electric
cables and devices.
BONNET DESIGN
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SHELL DESIGN
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MATERIALS
FOR
THERMAL
AND ACOUSTIC INSULATION IN THE
For engine‐mounted parts such as engine covers
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For engine mounted parts such as engine covers
1. Injecte po y propy ene coup e wit e t or po yuret ane foam‐ moulded absorbers are widely used
2. These material combinations are not suitable for a complete encapsulation due to their high weight between 3 and 4 kg/m2 .
BODY‐MOUNTED ACOUSTIC PARTS
Body‐mounted acoustic parts are often made of glass wool
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Body mounted acoustic parts are often made of glass wool or cotton felt, with phenolic resin as a binder treated .
Besides the good economics, these materials provide overall ood flammabilit resistance.
the resin has some disadvantages such as odour and VOC volatile organic compounds emissions.
NEW COMBINATION
A needled fibre material consisting of a combination of PP
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A needled fibre material consisting of a combination of PP and a variable amount of glass fibres in order to balance
such materials are not suited to the hi h tem eratures
close to
an
engine
since
they
are
limited
to
140
°C
(continuous engine surface temperature).
FUTURISTIC APPOROACH
Therefore there is a need to develop materials that
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Therefore there is a need to develop materials that
combines 1. mec anica strengt ,
2. acoustic effectiveness,
3. eat
nsu at on
an4. heat stability.
CONCLUSION It is foreseeable that the internal combustion engines of
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gfuture vehicles will require closed encapsulations in order
.
poses tremendous challenges for car manufacturers in terms of added complexity, weight, cost and thermal safety
pro ems.
REFERENCE [1] de ciutiis, h.; bürgin, t.; gorlato, l.: auswirkungen von verschiedenen motorraumkapsel‐
konzepten auf emissionen verbrauch und auf die thermische betriebssicherheit im
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konzepten auf emissionen, verbrauch und auf die thermische betriebssicherheit im motoPkws. In: Wärmemanagement des Kraftfahrzeugs. Expert Verlag, Renningen, 2006
[2] Lehmann,
D.:
Engineering
Process
for
an
Innovative
Underfloor Module.
Rieter
utomot ve on erence, r c , 2003
[3] Strategic Research Agenda of the European Road Transport Research Advisory Council, Dezember 2004
[4] Mantovani, M.; Lehmann, D.: Functional and Material Acoustic Optimization integrated . ‐ ‐
[5] Meschke,
J.;
Gaudino,
C.;
Bendell,
E.:
Design
and
Optimization
of
an
Engine
‐Mounted
Thermal‐ Acoustical Encapsulation. Rieter Automotive Conference, Zürich 2007
[6] Viktorovitch, M.: Acoustics of a Modular Engine Bay Encapsulation integrating a Porous . ,
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