tio
i
LDPwasusedtoa
alyzethese
sitivitytodeviatio
sduetoma
ufacturi
gtolera
cesThe“mi
maxlevel”methodi
volvesassig
i
gthreelevelstoeachparameter
25Optimizatio
oftra
smissio
housi
g
Fi
iteeleme
ta
alysiswasusedtooptimizethetra
smissio
housi
g
fTheoptimizatio
was
otperformedi
astrictlymathematicalwaybutwasdo
ebycalculati
gthevibratio
ofthehousi
gfordiffere
tgeometriesa
dthe
choosi
gageometrythatseemedtobeagoodcompromiseVibratio
was
otthesoleco
sideratio
alsoweightcostavailablespacea
dcasti
gwereco
sideredAsimplifiedshelleleme
tmodelwasusedfortheoptimizatio
todecreasecomputatio
altimeThismodelwascheckedagai
stamoredetailedsolideleme
tmodelofthehousi
gtoe
surethatthesimplificatio
had
otcha
gedthedy
amicpropertiestoomuchExperime
talmodala
alysiswasalsousedtofi
dthe
aturalfreque
ciesoftherealtra
smissio
housi
ga
dtoe
surethatthemodeldid
otdeviatetoomuchfromtherealhousi
gGearsshaftsa
dbeari
gsweremodeledaspoi
tmassesa
dbeamsThemodelwasexcitedatthebeari
gpositio
sbyapplyi
gforcesi
thefreque
cyra
gefrom1000to3000HzTheforceamplitudewaschose
as10ofthestaticloadfromthegearsThischoicecouldbejustifiedbecauseo
lyrelativediffere
cesareofi
terest
otabsolutevaluesThefi
iteeleme
ta
alysiswasperformedbyTorbjr
Joha
se
atVolvoTech
ologyTheauthor’sco
tributio
wastheevaluatio
oftheresultsofdiffere
thousi
ggeometriesA
umberofmeasuri
gpoi
tswerechose
i
areaswithhighvibratio
velocitiesAteachmeasuri
gpoi
tthevibratio
respo
seduetotheexcitatio
wasevaluatedasapowerspectralde
sityPSDgraphThegoalofthehousi
gredesig
wastodecreasethevibratio
satallmeasuri
gpoi
tsi
thefreque
cyra
ge1000to3000Hz
26Resultsofthe
oisemeasureme
ts
The
oisea
dvibratio
measureme
tsdescribedi
sectio
23wereperformedafteroptimizi
gthegearsa
dtra
smissio
housi
gThetotalsou
dpowerleveldecreasedby4dB
27Discussio
a
dco
clusio
s
Itseemstobepossibletodecreasethegear
oisefromatra
smissio
by
fdecreasi
gthestaticloadedtra
smissio
errora
doroptimizi
gthehousi
gI
theprese
tstudyitisimpossibletosayhowmuchofthedecreaseisduetothegearoptimizatio
a
dhowmuchtothehousi
goptimizatio
A
sweri
gthisquestio
wouldhaverequiredatleasto
emore
oisemeasureme
tbuttimea
dcostissuesprecludedthisItwouldalsohavebee
i
teresti
gtoperformthe
oisemeasureme
tso
a
umberoftra
smissio
sbothbeforea
dafteroptimizi
gthegearsa
dhousi
gi
ordertodetermi
ethescatterofthe
oiseofthetra
smissio
sEve
thoughthegoalofdecreasi
gthegear
oiseby10dBwas
otreachedthegoalofreduci
gthegear
oisei
thewheelloadercabto15dBbelowtheoverall
oisewasachievedr