8/2/2019 Carbon Fiber Springs

1/5

Case study on Carbon Fiber spring suspension for FORD ENDEVOUR THUNDER+

Abstract:Most of the SUVs (sports utility vehicles) available today, more so in the Indian market, are overdesigned,

especially at the chassis and suspension level. This is either done to accountfor the type of usage and road

conditionsorsimplytoextendthefactorofsafetyandproduct life.However,therearesomecategoriesofthese

SUVs that are more of ONRoad type and are less meantfor OFFRoad usage, in this case the suspension and

chassisare

either

left

with

their

original

design

(in

case

of

CKD

or

CBU)

which

are

some

way

designed

to

the

road

/

usageconditionsofthecountryofitsorigin.

Thepresentcasestudyisfocusedonquantifyingthevibrationandshockresponseusingtheexisting(default)metal

leaf springs and then by replacing them with carbonfibersprings made by M/s ARC INDUSTRIESIchalkaranji

(Maharashtra,INDIA). Avarietyofroadconditionswereusedtoassessthechangeinthevibrationresponse.

1.0IntroductionIntheclassificationofpersonalutilityvehicles,therearemainlytwocategories,namely

Vehicleslikecarsbuiltforsmoothness,stylingandoveralldriveandridecomfort Vehicles likeSportsUtilityVehicles,withbetterbuildquality,ruggednessand improvedroad

handling.

Thetradeoffbetweenthetwoarestraightandsimple;theformer ismoregood forcityandhighway

drive and the later more preferred for offroad and all terrain usage. Given this, the builtup of the

vehicle alsomatters greatly intermsof engine power, designof chassis, suspension, type and size of

tiresand soon.Considerations for smooth drive, ride and comfort are inadvertently compromised in

caseofaSUVowing itsbasicneedofbuildquality tohandle increased loads, roadsand terrains.The

suspensionsin

particular,

will

play

amajor

role

in

the

overall

design

and

thus

be

apart

of

the

overall

compromiseintermsofridecomfort.

In effect, the SUVs suffer from higher impact loads, vibration and shock as transferred from road

conditions; thedegreeof magnitudesmay vary on the SUV variants and makes, but the fact remains

thattheyarenowherecomparabletothetypeofcomfortachieved inthecarclassofvehicles,what is

thecompromiseincarcategoryisadifferentissuealtogether.

8/2/2019 Carbon Fiber Springs

2/5

Thepresent

case

study

is

taken

up

on

one

such

SUV

vehicle;

the

latest

in

the

Ford

range,

the

Endeavour

Thunder+, the task is a simple, straight forward comparison of transfer functions of vibration loads

below and above the rearspring mountings. The following testing conditions were consolidated for

testingboththedefaultmetalleafspringsandthereplacementcarbonfibersprings.

2.0MeasurementConditions/SetupandInstrumentation

A typical all mix road condition about 11 km were selected; the terrain has combination ofgravelstretch,humpsandbumps,softasphaltedroadandfinallysomestretchofmuddyuneven

road.

Approachspeedsatselectroadhumpsvaryingbetween40to80kmph. Midgearcontinuousrunonunevenmudterrain. Acceleration/Decelerationonflat asphaltedroadintherangeof100km(up/down) Twotriaxialaccelerometers,onemountedonthecrossbarof the rearwheel (ondifferential

dome) and the secondwith the certified seat adaptor (for whole bodyvibration) on themid

roadof thepassengerseating.Bothof themconnectedtoMobileDataacquisitionsystem for

realtimerecordingofvibrationdata.

PicturesofSetupandPreparation

Vehiclebeingprepared

formounting

accelerometers

Triaxialaccelerometer

mountedonrearaxle

differential

ExistingMetalLeaf

springsontherear

wheel

Instrumentation&seat

adaptorforvibration

mesurements

8/2/2019 Carbon Fiber Springs

3/5

Picturesof

change

over

to

Carbon

Fibre

springs

3.0MeasurementsandResultsThevibrationaccelerationdata from2triaxialaccelerometerswerecontinuouslyrecorded forthe11

kmstretchoftesting(bothwiththemetalandcarbonsprings);themeasureddatawerepostprocessed

fortwoparameters

1. Absolute acceleration values g at specific time events; this is related to vehicle speed &specificroadcondition;theconditionsarerepeatedforboththetypeofsprings.

2. Transfer function values between the reference (below springs) and the responseaccelerometers(ontheseat)tocharacterizetheeffectofthespringperformance.

3. The vehicle had the same loading conditions all through the test; 5 adults + driver wereoccupying

the

seating

area.

Table below puts across direct comparison of Acceleration g values for a certain set of condition

commonforboththetypeofsprings

8/2/2019 Carbon Fiber Springs

4/5

60kmto

Hump

100km

road

meters

Gravel

speed

Reversi

*

Predo

4.0Tes

0

0.2

0.4

0.6

0.8

1

1.2

easureme

20kmdece

Crossing,br

to 30km d

rumble cro

road contin

g8meterd

minant

freq

Graphs

0

10

imevsAmp

t/RoadCo

lerationfl

akingdistan

celeration

sing, brakin

uous vibrat

istance20k

ency

instan

500

5

Time insec

litudedispl

dition

tasphaltro

ce15meter

flat asph

g distance

ion at 70

mph

taneous

vib

1

Frequ

0

20

40

60

80

100

120

nds(0seco

cement(m

Acce

M

ad

s

lt

34

m

ation

(can

b

00

encyinHz

0

dsreprese

) HumpC

lerationval

location(+

talspring

1.82

2.11

1.52

0.47

e

referred

t

1500

5

tpeakofh

rossingat6

ein

g*

at

zdirection)

Fibrespr

0,

0.

0.

0.

o

shock)

20

1

mp)

kmph flat

seat

ing

2

1 A

5

1 A

va

3

00

0

AsphaltRoa

emarks

erage of

umblings

eraged

lue

Metal

Carbon

Metal

Carbon

d

8/2/2019 Carbon Fiber Springs

5/5

5.0ConclusionsandRemarks Thefactoryfitmetalleafspringsarerigidandofferhigherdynamicforcetransfersthroughtheir

structureandfinallytotheseatingareaofthevehicle;thiscouldbeadefaultconstraintofusing

the metal springs as the design considerations of the vehicle define the spring usage and its

overallbuildup.

Themiddleandrearseatingareasaremostaffectedbythevibrationandshocktransferthroughtherearspringsets;asthelengthoftheoverhangofthechassisoverthefulcrumpointofrear

wheeldirectlydefinestheamplificationfactorofdisplacement,therigidconnectionsofferedby

themetalspringdoescontributetotheoverallcomfortfeelinthecabinseatingarea.

In contrast, the carbon fiber spring offers a overall improved performance in attenuating theinput shocks to a great extent; a factor of 4 times reduction in observed in most of the

predominantfrequenciesthatwereconsideredforthetests.

Thecarbonfiberspringsetsofferahigherdegreeofverticaldirectiondeflection,whilethisisasmall concern in terms of static deformation, the overall reduction in dynamic displacements

combinedwithincreasedvibrationdampingrationsoffersuperiorridecomfort.

As

the

metal

springs

are

in

a

stacked

set,

relative

lateral

motion

tend

to

create

quirk

noise

over

time,thisiscompletelyovercomeincaseofsinglebladecarbonspring.

Static deformation in metal springs is a known phenomenon, while this factor is almostnegligibleincaseofcarbonspringstested.

Theoverall longitivityofthetestedcarbonspringsareyettobeprovedasthesamplestestedareforlimitedperiodoftime.

0

20

40

60

80

100

120

10 5 0 5 10

Metal

Carbon

Time inseconds(0secondsrepresentpeakofhump)

TimevsAmplitudedisplacement(mm) HumpCrossingat80kmph flatAsphaltRoad