vib project full nfinal 21 june
TRANSCRIPT
-
8/12/2019 Vib Project Full Nfinal 21 June
1/35
PROJECT REPORT
VEHICLE BODY VIBRATIONS AND DRIVELINEFLUCTUATION ANALYSIS
Submitted to
Dr Sub!"#! R"$!e%"
&ECH '())*VIBRATIONS IN &ACHINES AND STRUCTURES
B+
,!"r"-ur$"r A%i.$+" '/(01'2
CONCORDIA UNIVERSITY
FACULTY OF EN,INEERIN, AND CO&PUTER SCIENCE
DEPART&ENT OF &ECHANICAL AND INDUSTRIALEN,INEERIN,
Page | 1
-
8/12/2019 Vib Project Full Nfinal 21 June
2/35
Ab#tr"3t
The vehicle driving comfort and passenger safety are the most important factors influencing
vehicle quality. Vibration problem predominantly occurs in case of on-road vehicles because of
the unevenness of the road surface on which the vehicle travels. In order to increase driving
comfort and passenger safety, it is necessary to analyse the vibrations induced in vehicle body
and driveline because of continuously varying road input. In this study, a 4 D ! half car model
is considered for the analysis. "s a first part of the study, the natural frequencies of the vehicle
are calculated as per the given data. In the later part free vibration response of the vehicle to
sinusoidal bump as well as potholes is determined with the help of simulin#. "nother important
factor considered in this study is the fluctuation in output shaft speed because of the angularity of
$oo#%s &oint in vehicle driveline. The fluctuation response of the output shaft because of this
angularity is also determined.
Page | 2
-
8/12/2019 Vib Project Full Nfinal 21 June
3/35
Li#t o4 Fi5ure#
!igure ' Vehicle vibration model with driveline configuration ()
!igure * " $alf +ar odel ith 4 D ! (
!igure / ode 0hapes of the system '1
!igure 4 $oo#2s 3oint simplified diagram '
!igure 1 5hasing of $oo#2s &oint '6
!igure )7 Details of 8oad bump in the form of sine wave *(
!igure 7 Details of 5otholes as a road input. *(
Page | 3
-
8/12/2019 Vib Project Full Nfinal 21 June
4/35
T"b6e o4 Co.te.t#
"bstract
9ist of !igures
'. Introduction (1
'.'7 :eed for Vibration "nalysis..................................................................................... (1
'.*7 5roblem Description.................................................................................................. ()
*. Vibration "nalysis of $alf +ar odel........................................................................... (
*.'7 $alf +ar odel ;inematics....................................................................................... (6
*.*7 +alculation of :atural !requencies and ode shapes............................................... ''
*.*.'7 atlab 5rogram to !ind hr===============. *
/.47 8esponse of Vehicle to potholes at )(#m>hr===============. *6
/.17 8esult Interpretation.................................................................................................. *6
4. +onclusion..................................................................................................................... /*
1. 8eferences....................................................................................................................... //
Page | 4
-
8/12/2019 Vib Project Full Nfinal 21 June
5/35
) INTRODUCTION
The vehicle driving comfort and passenger safety are the most important factors influencing
vehicle quality. Vibration problem predominantly occurs in case of on-road vehicles because of
the unevenness of the road surface on which the vehicle travels. 8esearch has been going on for
many years to analyse vehicle vibration and methods to reduce them. These factors play an
important in ride comfort, vehicle safety and overall vehicle performance. ?4@, ?*@
Vibrations induced in vehicles can be categoriAed in two types. The first one is deterministic
vibration which is caused by rotating parts of the vehicle. !ew numerical and analytical methods
can be used to predict Vibration characteristic of this type. The second type is random vibration
which is caused by unpredicted loads such as road roughness and wind. The vibration
characteristics of this type are difficult to predict. 5robabilistic approach can be used for
analysing random vibrations.?/@
) ) Need For Vibr"tio. A."6+#i#7
ost of the mathematical modelling tools for vehicle vibration analysis assume that all
parameters of vehicle systems are deterministic. "ctually, there may be a variation in spring
stiffness and damping production tolerances and>or wear. "lso the uneven loading conditions
may induce stochastic variations in vehicle body mass and tires. In cars and buses, weight and
placements of passengers often eBhibit significant variability. Therefore, it is very essential to
analyse the problem of vehicle vibration sub&ect to uncertain parameters.?4@
Page | 5
-
8/12/2019 Vib Project Full Nfinal 21 June
6/35
Vehicle random vibration analysis is of utmost importance because practically all vehicle
systems are sub&ected to random dynamic environments. These unpredictable random vibrations
may damage the machine elements. The random vibration analysis helps determining the design
parameter of the road vehicles.?/@ "long with these, torsional and bending fluctuations of
driveline is one of the ma&or issues researchers are facing. These fluctuations are caused because
of the angularity between driveshaft and universal &oint. !or the simplicity, the angularity
between driveshaft and universal &oint is considered constant. $owever, the equality of
angularity is very difficult to maintain on uneven road profiles. Therefore, an attention must be
paid towards analysing bending and torsional fluctuations. ?'@
) 8 Prob6em De#3ri-tio.7
" 4 D ! half car model is considered for vibration analysis. " half car model includes body
bounce and pitch motion. ith the help of the given data the following factors are determined7
Fi5ure ) Ve!i36e 9ibr"tio. mode6 :it! dri9e6i.e 3o.4i5ur"tio. ;)sec L!ront tireM
K*E *6.*) rad>sec L8ear tireM
K/E ).(6 rad>sec LCody bounceM
K4E 4.(/ rad>sec LCody pitchM
Page | 15
-
8/12/2019 Vib Project Full Nfinal 21 June
16/35
8 ( Hoo$ # Joi.t "."6+#i#7
De4i.itio. ".d A--6i3"tio.7
The function of the Nniversal &oints is to transmit the torque and rotational motion from one shaft
to another when their aBes are at inclination at some angle. This angularity may change
continuously during the operation. Nniversal &oint is as essential part of the vehicle transmission.
The universal &oint in vehicles find its application in following three areas7 ? @
LaM 5ropeller shaft end &oints between longitudinally front mounted gearboB and rear final driv
aBle.
LbM 8ear aBle drive shaft end &oints between the sprung final drive and the unsprung rear whe
stubaBle.
LcM !ront aBle drive shaft end &oints between the sprung front mounted final drive and th
unsprung front wheel steered stub aBle.
Due to the severe wor#ing conditions, special universal &oints #nown as constant velocity &oint
are employed. These &oints have been designed to absorb torque and speed fluctuations and tooperate reliably with very little noise and wear having long life. ? @
8 ( ) Si.56e Hoo$ # Joi.t A."6+#i#7
In hoo#2s-type coupling, when a drive is transmitted through an angle, the output shaft does not
rotate through /)( degrees at a constant speed. The output shaft undergoes cyclic speed
variation. The cyclic speed variation and vibrations associated with it are insignificant when
drive angle is less than 1 degrees but this factor has to be ta#en into consideration for larger
angle variations.? @ !igure / shows the simplified version of $oo#2s &oint. The equation for the
Page | 16
-
8/12/2019 Vib Project Full Nfinal 21 June
17/35
velocity ratio for the driving and the driven shaft can be derived from the figure in order to
analyAe the variation in output shaft speed because of angularity. !irst the driveshaft is turned
through an angle O so that point P moves to Pi .The point Q moves about aBis C, through an
angle 4R subtended by an arc Qd and it moves in a vertical plane to Qi through an elliptical path.
? @
Page | 17
-
8/12/2019 Vib Project Full Nfinal 21 June
18/35
Fi5ure / Hoo$ # Joi.t #im-6i4ied di"5r"m ; hr and )(#m>hr is determined. Thedetails of the road profiles are as shown in the figures.
!igure )7 Details of 8oad bump in the form of sine wave
!igure 7 Details of 5otholes as a road input.
Page | 21
-
8/12/2019 Vib Project Full Nfinal 21 June
22/35
( SI&ULATION OF HALF CAR &ODEL
Page | 22
-
8/12/2019 Vib Project Full Nfinal 21 June
23/35
Simu6"tio. &ode6 4or Dri9e6i.e tor#io."6 ".d be.di.5 46u3tu"tio.#7
Page | 23
-
8/12/2019 Vib Project Full Nfinal 21 June
24/35
( ) Re#-o.#e o4 Ve!i36e to Si.u#oid"6 bum- :it!out "33e6er"tio. 7
Re#-o.#e o4 Ve!i36e to Pit3! ".d bou.3e motio. :it!out "33e6er"tio.
Ve!i36e Dri9e6i.e F6u3tu"tio.# :it!out "33e6er"tio.
Fro.t ".d Re"r Su#-e.#io. F6u3tu"tio.#
Page | 24
-
8/12/2019 Vib Project Full Nfinal 21 June
25/35
-
8/12/2019 Vib Project Full Nfinal 21 June
26/35
( 8 Re#-o.#e o4 Ve!i36e to Si.u#oid"6 Bum- :it! A33e6er"tio.7
Ve!i36e re#-o.#e to -it3! ".d bou.3e motio. :it! "33e6er"tio.
Ve!i36e dri9e6i.e 46u3tu"tio.# :it! "33e6er"tio.
Page | 26
-
8/12/2019 Vib Project Full Nfinal 21 June
27/35
Fro.t ".d Re"r #u#-e.#io. F6u3tu"tio.# :it! "33e6er"tio.
Page | 27
-
8/12/2019 Vib Project Full Nfinal 21 June
28/35
( ( Re#-o.#e o4 Ve!i36e to Pot!o6e# "t /0$m !r7
Dri9e6i.e F6u3tu"tio.# "t -ot!o6e# "t /0$m !r
Page | 28
-
8/12/2019 Vib Project Full Nfinal 21 June
29/35
Fro.t ".d Re"r #u#-e.#io. 9ibr"tio.# "t -ot!o6e# "t /0$m !r
Page | 29
-
8/12/2019 Vib Project Full Nfinal 21 June
30/35
( / Re#-o.#e o4 Ve!i36e to Pot!o6e# "t ' $m !r
Ve!i36e dri9e6i.e 46u3tu"tio.# "t -ot!o6e# :!e. ru..i.5 "t ' $m !r
Page | 30
-
8/12/2019 Vib Project Full Nfinal 21 June
31/35
Fro.t ".d Re"r Su#-e.#io. Vibr"tio.# "t -ot!o6e#
( 0 Re#u6t I.ter-ret"tio.7 "ccording to the vehicle response to sinusoidal bump and potholes at
different speed, following results can be interpreted7
!or the sinusoidal bump, two cases are considered. In first condition it is assumed that vehicle is
moving without any acceleration. The second condition assumes that vehicle moves with
acceleration of m>s* for /.1 sec. The vehicle is moving with 41#m>hr It can be seen that the
fluctuations due to vehicle bounce and pitch motion are more compared to those when vehicle is
moving without acceleration. Cut the vehicle which is moving without acceleration is settleling
down after the bump has passed.
Page | 31
-
8/12/2019 Vib Project Full Nfinal 21 June
32/35
n the road bump, vehicle%s pitch and bounce motion induces angularity of &oints in the driveline
which causes output shaft to fluctuate.
hen vehicle is moving on potholes7
It can be observed that when vehicle is moving at )(#m>hr, driveline fluctuations are more
significant. If the operating frequency of the vehicle coincides with pitch or bounce frequency of
the vehicle, there will be large variation in the angularity of the driveshaft. The significant
angularity in between the &oints increases driveline fluctuations dramatically.
Page | 32
-
8/12/2019 Vib Project Full Nfinal 21 June
33/35
/ CONCLUSION
In this study, a 4D ! half car model is considered and its responses to two different types of
road inputs are determined. "s a first part, the natural frequencies and corresponding mode
shapes of the half car model were calculated with the help of atlab program. nce the
properties were #nown a detailed analysis of vehicle response to varying road profiles at
different speeds was carried out. " road profile was provided in the form of sinusoidal bump and
potholes. "lso in the later part, driveline fluctuations which are induced due to the angularity of
$oo#%s &oint are discussed. !or this a detailed analysis of $oo#%s &oint is considered here
Therefore, it can be seen that with the help of simulin#, a half car model provides a good means
for determining the body vibration and driveline fluctuations.
Page | 33
-
8/12/2019 Vib Project Full Nfinal 21 June
34/35
0 REFERENCES
?'@ *('(> (* *(
?1@ +. C. 5atel', 5. 5. Hohil' and C. Corhade, S D
-
8/12/2019 Vib Project Full Nfinal 21 June
35/35
?)@ T. ar#el, ". Croo#er, T. $endric#s, V. 3ohnson, ;. ;elly, C. ;ramer, . %;eefe, 0.
0pri#, ;. ip#e, S"DVI0 87 a systems analysis tool for advanced vehicle modelingS, :ational
8enewable