Vib Project Full Nfinal 21 June

8/12/2019 Vib Project Full Nfinal 21 June

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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,

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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.

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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. *(

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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....................................................................................................................... //

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) 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@

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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

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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

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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.

? @

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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.

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( SI&ULATION OF HALF CAR &ODEL

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Simu6"tio. &ode6 4or Dri9e6i.e tor#io."6 ".d be.di.5 46u3tu"tio.#7

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( ) 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.#

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( 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.

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Fro.t ".d Re"r #u#-e.#io. F6u3tu"tio.# :it! "33e6er"tio.

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( ( Re#-o.#e o4 Ve!i36e to Pot!o6e# "t /0$m !r7

Dri9e6i.e F6u3tu"tio.# "t -ot!o6e# "t /0$m !r

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Fro.t ".d Re"r #u#-e.#io. 9ibr"tio.# "t -ot!o6e# "t /0$m !r

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( / 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

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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.

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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.

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/ 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.

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0 REFERENCES

?'@ *('(> (* *(

?1@ +. C. 5atel', 5. 5. Hohil' and C. Corhade, S D


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?)@ 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

Vib Project Full Nfinal 21 June

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